Metal film forming method

A metal film forming method comprises steps of: PA0 forming a non-monocrystalline metal film principally composed of aluminum, in contact, at least in a part thereof, with a monocrystalline metal principally composed of aluminum; and PA0 heating the non-monocrystalline metal film to convert at least a part thereof into monocrystalline state.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method for forming a thin metal film, 
and more particularly to a method for forming a thin metal film 
principally composed of aluminum, adapted for use in wirings for example 
for semiconductor devices. 
2. Related Background Art 
In the electronic semiconductor devices or integrated circuits, the 
electrodes and wirings have principally been composed of pure aluminum or 
a metal principally composed of aluminum, such as Al-Si. Aluminum has 
various advantages, such as low cost, high electrical conductivity, 
formation of a dense surfacial oxide film capable of chemically protecting 
the interior, and good adhesion to silicon. 
Recent advancements in the level of integration in the ultra large-scale 
integrated circuits (ULSI) are requiring finer geometry and multi-layered 
structures in the wirings. For this reason there is required a deposition 
method for aluminum film, excellent in step coverage, in order to avoid 
breakage of wirings at a stepped portion. Also required is a deposition 
method capable of deposition into via holes such as small contact holes or 
through-holes with satisfactory step coverage, or selective deposition in 
such via holes. The wirings have to be highly reliable, excellent in 
resistances to electromigration and stress migration. 
In the conventional large-scale integrated circuits (LSI), the 
deterioration in step coverage at the stepped portions has been prevented 
by formation of a tapered portion at a step, but the step can no longer be 
tapered but has become vertical with the miniaturization of geometry. 
Since sputtering is based on linear particle movement in vacuum, the film 
thickness at the vertical step becomes inevitably smaller than in other 
places so that satisfactory step coverage cannot be maintained. Also via 
holes cannot be filled in completely but generate gaps therein, so that 
satisfactory contact cannot be expected. 
On the other hand, deposition of Al or Al-Si can be deposited by chemical 
vapor deposition (CVD) in which aluminum-containing gas is transported 
into a space including a substrate and a desired deposition film is formed 
by absorption and reaction of a raw material gas on the substrate surface. 
Such CVD method has a feature of satisfactory step coverage at the stepped 
portion, because it utilizes the absorption and reaction of the raw 
material gas on the substrate surface. Selective deposition is also 
possible, depending on the specy of the substrate surface. The CVD method 
generally employs an organometallic material, such as trimethylaluminum 
(TMA; (CH.sub.3).sub.6 Al.sub.2), triisobutylaluminum (TIBA; (iC.sub.4 
H.sub.9).sub.3 Al), or dimethylaluminum hydride (DMAH; (CH.sub.3).sub.2 
HAl) as the raw material gas. As is already known, the Al film obtained by 
the CVD method is superior in step coverage to that obtained by 
sputtering. Also the CVD method is capable of selective deposition on the 
exposed Si area on a Si substrate bearing SiO.sub.2 thereon. 
The CVD method utilizing DMAH and hydrogen (Tsubouchi et al., Nikkei 
Microdevices, Jun. 1, 1990; p.96-102) is capable of selective growth of Al 
or Al-Si solely on a conductive substrate such as Si or a metal, and the 
aluminum selectively deposited on Si substrate becomes monocrystalline. 
The aluminum area selectively grown on Si, being monocrystalline, is free 
from errosion or spike generation or deterioration in contact resistance 
at the Si interface in the thermal treatment. Also after aluminum is 
selectively deposited in the via hole, it can be deposited over the entire 
area of the substrate, so that such via hole can be completely planarized 
by deposition of Al or Al-Si. Consequently satisfactory wirings can be 
formed, without breakage in the steps, contacts or via holes in the 
miniaturized ULSI. 
Electromigration (EM) is a wiring breakage which occurs when the wiring is 
continuously given a current, and such breakage is considered to occur at 
the crystal grain boundary of Al wiring. Also stress migration (SM) is a 
wiring breakage by a stress in the aluminum wiring, induced by an 
insulation film such as SiO or SiN provided on said wiring. Al or Al-Si is 
generally polycrystalline in crystallographic sense. Polycrystals are 
composed of monocrystalline grains. Each monocrystalline area is called 
crystal grain, and the interface of grains is called grain boundary. In 
general, in ULSI's, the size of crystal grain is generally in the order of 
a micron. The electromigration and the stress migration are major causes 
deteriorating the reliability of the wirings of Al or Al-Si, and 
improvement in the resistance to such migration phenomena is an essential 
condition for improving the reliability of the metal wirings in ULSI's. 
Although investigations are being made for improving the resistance to 
electromigration and stress migration by adding a small amount of Cu or Ti 
to Al or Al-Si, or by using non-aluminum metal such as W, Mo or Cu, no 
other materials than Al or Al-Si can be selected for satisfying all the 
requirements such as adhesion to SiO.sub.2, ease of bonding and ease of 
microworking. 
The digest of IEDM (international Electron Devices Meeting) held by IEEE in 
December 1989 reported, in pages 677-681, that the resistances to EM and 
SM were significantly improved if Al was monocrystalline. 
Thus the wiring of Al or Al-Si, if made in monocrystalline state instead of 
conventional polycrystalline state, can satisfy the requirements of 
adhesion, ease of bonding and ease of microworking, and can also attain 
high reliability without breakage by electromigration or stress migration. 
However, in the ULSI's, the wirings with monocrystalline Al or Al-Si have 
not been realized as will be explained in the following. 
The monocrystalline thin Al films which have been reported thus far are all 
formed on monocrystalline Si substrates. The report on improvement in 
EM/SM resistances by monocrystalline Al (aforementioned 1989 IEDM digest) 
is also based on the measurement on an Al film formed by CVD on a Si 
substrate. On the other hand, the Al or Al-Si wirings in ULSI's are formed 
on an insulating film such as SiO.sub.2. On an insulating film such as 
SiO.sub.2, the Al film formed by sputtering, CVD or ICB (ion cluster beam) 
is polycrystals consisting of crystal grains of the order of a micron. 
According to Tsubouchi et al. (reference cited before), after selective 
deposition of monocrystalline Al (first Al) in the via hole, second Al can 
be deposited over the entire surface of the substrate. Though the first Al 
is monocrystalline, the second Al is still polycrystalline, consisting of 
crystal grains of the order of a micron. 
SUMMARY OF THE INVENTION 
The present invention, attained in consideration of the foregoing, is based 
on a new finding of the present inventors, that an Al film present on an 
insulating member such as SiO.sub.2 can also be made monocrystalline by a 
heat treatment if monocrystalline Al is present in a lower layer. 
In the field of semiconductor devices in which a higher level of 
integration and a higher speed have been sought for by size reduction in 
circuit geometry as explained above. There is still room for improvement 
in the reliability of such semiconductor devices which have already been 
improved in the level of integration and in functions. 
An object of the present invention is to provide a method for converting a 
non-monocrystalline thin metal film, for example a wiring layer, into 
monocrystalline state, thereby improving the antimigration resistance of 
the wiring layer. 
Another object of the present invention is to provide a thin metal film 
forming method capable of forming aluminum single crystal on an insulation 
film. 
Still another object of the present invention is to provide a thin metal 
film forming method comprising steps of forming a non-monocrystalline 
metal film principally composed of aluminum in contact, at least in a part 
thereof, with a monocrystalline metal principally composed of aluminum, 
and heating said non-monocrystalline metal film to convert at least a part 
thereof into single crystal. 
Still another object of the present invention is to provide a thin metal 
film forming method comprising steps of forming a non-monocrystalline 
metal film principally composed of aluminum in contact, at least in a part 
thereof, with a monocrystalline metal principally composed of aluminum, 
converting said non-monocrystalline metal film into amorphous or 
microcrystalline state, and heating said non-monocrystalline metal film in 
said amorphous or microcrystalline state to convert at least a part 
thereof into monocrystalline state. 
Still another object of the present invention is to provide a thin metal 
film forming method comprising a step of forming an insulation film on a 
principal face of a semiconductor substrate, a step of forming an aperture 
in said insulation film thereby exposing the surface of said semiconductor 
therein, a step of depositing a single crystal of a first metal 
principally composed of aluminum in said aperture, a step of forming a 
thin film of a second metal principally composed of aluminum on the single 
crystal of said first metal and on said insulation film, and a step of 
heating the thin film of said second metal thereby converting at least a 
part thereof into a single crystal, utilizing said single crystal of said 
first metal as a seed crystal. 
Still another object of the present invention is to provide a thin metal 
film forming method comprising a step of forming an insulation film on a 
principal face of a semiconductor substrate, a step of forming an aperture 
in said insulation film thereby exposing the surface of said 
semiconductor, a step of depositing a single crystal of a first metal 
principally composed of aluminum in said aperture, a step of forming a 
thin film of a second metal principally composed of aluminum on the single 
crystal of said first metal and on said insulation film, a step of 
converting the thin film of said second metal into amorphous or 
microcrystalline state, and a step of heating the thin film of said second 
metal to convert at least a part thereof into monocrystalline state, 
utilizing said single crystal of said first metal as a seed crystal. 
The present invention can convert a non-monocrystalline thin metal film, 
formed in contact with a monocrystalline metal, into monocrystalline state 
by heating said metal film, utilizing said monocrystalline metal as a seed 
crystal. Such monocrystalline thin film can be used as a wiring layer in a 
semiconductor device, thereby improving the migration resistance. 
Alternatively, if the non-monocrystalline thin metal film is in 
polycrystalline state, it may be once converted into amorphous or 
microcrystalline state (naturally a state of microcrystals mixed in 
amorphous substance is also acceptable) prior to heating, and such process 
further improves the migration resistance of the thin metal film.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a preferred embodiment of the present invention, a heat treatment is 
applied to an Al film, containing monocrystalline Al and 
non-monocrystalline Al in mutual contact in at least a part thereof, 
thereby converting the non-monocrystalline Al into monocrystalline state. 
In another preferred embodiment of the present invention, an ion 
implantation, followed by a heat treatment, is applied to an Al film, 
containing monocrystalline Al and non-monocrystalline Al in mutual contact 
in at least a part thereof, thereby converting the non-monocrystalline Al 
into monocrystalline state. 
The monocrystalline Al used as the seed crystal is preferably formed by 
aluminum deposition on monocrystalline silicon by a CVD method utilizing 
dimethylaluminum hydride (Al(CH.sub.3).sub.2 H), monomethylaluminum 
hydride (Al(CH.sub.3)H.sub.2) or triisobutylaluminum (Al(iC.sub.4 
H.sub.9).sub.3) as the raw material gas. 
On the other hand, the non-monocrystalline Al may be formed by a method for 
forming polycrystalline Al by depositing Al by the CVD method utilizing 
the above-mentioned gas onto a surface of a material other than 
monocrystalline Al, a method of forming polycrystalline Al by sputtering, 
or a method of forming polycrystalline Al by a CVD method utilizing 
trimethylaluminum (Al(CH.sub.3).sub.3) or diethylaluminum chloride 
(Al(C.sub.2 H.sub.5).sub.2 Cl). 
The monocrystalline Al seed may be so provided that at least a part thereof 
is in contact with the non-monocrystalline Al to be converted into 
monocrystalline state. For example the seeds and the insulation film may 
be arranged in a grating pattern, or the seeds may be deposited in via 
hole patterns formed in the insulation film, or the seeds and the 
insulation films may constitute a line-and-space pattern. 
In still another preferred embodiment of the present invention, 
monocrystalline Al formed in an aperture (via hole) in an insulation film 
is used as the speed crystal, and the non-monocrystalline Al in other 
parts is converted into monocrystalline state by heating. It is 
particularly preferable to form monocrystalline Al in the via hole for 
electrical contact by selective Al deposition therein, then to 
non-selectively deposit Al also on the insulation film, and to apply the 
heat treatment thereby converting Al on the insulation film into 
monocrystalline state. Such method allows to obtain a flat Al film without 
a recess formation in the Al film on the via hole. 
The monocrystalline Al used as the seed is preferably formed by a CVD 
method utilizing alkylaluminum hydride and hydrogen (said method 
hereinafter called Al-CVD method). This CVD method is capable of selective 
Al deposition on an electrondonating surface, such as monocrystalline 
silicon. 
Said alkylaluminum hydride can be dimethylaluminum hydride 
(Al(CH.sub.3).sub.2 H) or monomethylaluminum hydride (AlCH.sub.3 H.sub.2). 
The non-monocrystalline Al, prior to conversion to monocrystalline state, 
can be formed by ordinary sputtering or CVD. The raw material gas for such 
CVD method can be trimethyl aluminum (Al(CH.sub.3).sub.3), triisobutyl 
aluminum (Al(iC.sub.4 H.sub.9).sub.3), or diethylaluminum chloride 
(Al(C.sub.2 H.sub.5).sub.2 Cl). Such method allows to obtain wirings 
adapted for use in semiconductor devices. 
Now the present invention will be clarified in greater detail by 
embodiments thereof shown in the attached drawings. 
FIG. 1 gives schematic cross-sectional views showing the single crystal 
forming method of the present invention, applied to formation of wirings. 
In FIG. 1A, there are shown a substrate 1 composed for example of 
monocrystalline Si; an insulation film 2 composed for example of silicon 
oxide; a monocrystalline Al 3 serving as a seed; and an Al layer 4 to be 
converted into monocrystalline state by the method to be explained later. 
At first the insulation film 2 is formed on the substrate 1. 
Then a via hole is formed for example by reactive ion etching, thereby 
exposing a part of the surface of the substrate 1. Said insulation film 
can be composed, for example, of a silicon oxide film, a silicon nitride 
film or a silicon oxinitride film such as NSG, PSG, BSG or BPSG. These 
films can be formed by thermal oxidation, CVD or sputtering already known. 
Then monocrystalline Al (first Al) 3 is formed in the via hole. In this 
operation, the above-explained Al-CVD method may be employed to form 
monocrystalline Al selectively in said via hole. The substrate surface 
temperature in this operation is in a range at least equal to the 
decomposition temperature of alkylaluminum hydride but not exceeding 
450.degree. C., more preferably from 260.degree. to 440.degree. C., and 
most preferably from 270.degree. to 350.degree. C. 
Thus formed monocrystalline Al has satisfactory interface with the 
underlying Si, and also has satisfactory surface properties. 
After the formation of monocrystalline Al 3 in the via hole, 
non-monocrystalline Al (second Al) 4 is formed on the monocrystalline Al 3 
and on the insulation film 2. In this case there can be employed already 
known deposition methods other than said AlCVD method. If the Al-CVD 
method is to be employed, the insulation film 2, constituting an electron 
non-donating surface, is subjected to a surface modifying step such as 
supply of ions or electrons by plasma, plasma damage or ion implantation 
to obtain a practically electron-donating surface. The non-monocrystalline 
Al can be formed also on the insulation film by the introduction of such 
surface modifying step (FIG. 1A). 
Subsequently the heat treatment to be explained later is conducted to 
convert the non-monocrystalline Al into a monocrystalline state. Said heat 
treatment may be conducted at this point, or after the formation of an 
insulation film 5. 
Also said heat treatment may be conducted after the non-monocrystalline Al, 
to be converted into monocrystalline state, is patterned into the form of 
desired wirings, or prior to said patterning. 
The insulation film 5 is formed after the patterning of Al 4, as shown in 
FIG. 1B. Said insulation film 5 may be formed, like the insulation film 2, 
by CVD or sputtering. 
The wirings consisting of monocrystalline Al can be obtained in this 
manner. 
In case of forming multi-layered wirings, the above-explained procedure is 
repeated to obtain a two-layered wiring structure of monocrystalline Al as 
shown in FIG. 1C. A three or four-layered wiring structure can also be 
obtained by repeating said procedure further. 
In FIG. 1C, there are shown an interlayer insulation film 5, selectively 
deposited monocrystalline Al 6, Al 7 in converted monocrystalline state, 
and a protective insulation film 8. 
In the foregoing description, the metal principally composed of Al is 
limited to pure aluminum, but it is also possible to convert Al containing 
Si in a small amount, for example 1%, namely Al-Si, to monocrystalline 
state. In such case, the monocrystalline Al-Si seed can be formed, in the 
aforementioned Al-CVD method, by introducing Si-containing gas such as 
SiH.sub.4 or Si.sub.2 H.sub.6 together with alkylaluminum hydride gas and 
hydrogen gas. 
FIG. 2 shows examples of arrangement of monocrystalline Al seeds. In an 
example shown in FIG. 2A, apertures of a lateral length of L1 are formed 
in a checkered pattern in an insulation film 11, formed for example on a 
Si surface, and monocrystalline Al is selectively deposited in said 
apertures. An unrepresented non-monocrystalline Al film is formed on the 
insulation film 11 and on the monocrystalline Al in the apertures 12, and 
is converted into monocrystalline state by heating, utilizing the 
monocrystalline Al as the seeds. In an example shown in FIG. 2B, apertures 
of a lateral length L2 are formed as via hole pattern with an interval L3, 
and, in an example in FIG. 2C, a line-and-space pattern is formed by 
insulators 11 of a width L5 and apertures 12 of a width L4. In either case 
the monocrystalline Al is deposited selectively in the apertures, and an 
unrepresented non-monocrystalline Al film is formed, covering the 
monocrystalline Al and the insulator. Upon heating, the 
non-monocrystalline Al film is converted into monocrystalline state, 
utilizing the monocrystalline Al as the seeds. 
In the following there will be explained the heat treating method for 
converting Al or Al-Si into monocrystalline state. 
The basic procedure consists of preparing a specimen of a cross section as 
shown in FIG. 1A or 1B, and subjecting said specimen to heating step. 
Observations were made with X-ray diffraction, conventional RHEED and 
scanning .mu.-RHEED microscope, before and after the heating. 
The transition of the second Al from the polycrystalline state to the 
monocrystalline state by heating is ascribed to the rearrangement of Al 
atoms, based on the increased flowability thereof. It is already known 
that a semiconductor containing a covalent bonding such as Si or GaAs 
present on a thin insulation film can be converted into monocrystalline 
state by heating. It is also known that an Al or Al-Si film, present on an 
insulation film, can be grown into polycrystals consisting of crystal 
grains of several microns by a heat treatment of 450.degree. C., but the 
present invention is based on a finding that Al or Al-Si present on an 
insulator can be converted into monocrystalline state over an area in 
excess of 10 .mu.m if a monocrystalline Al area is present under such Al 
or Al-Si film. 
Heating of the specimen can be achieved, for example, by heating in an 
electric oven with an atmosphere of H.sub.2, N.sub.2 or Ar or a mixture 
thereof, heating in vacuum, heating with a rapid thermal annealer (RTA), 
heating with a laser, heating with a linear heater such as a carbon 
heater, high frequency heating, lamp heating or electron beam heating. 
In a LSI in general, a pure Al film or an Al-Si film formed on Si reacts, 
when heated, with Si thereby causing erosion of the Si substrate or a leak 
in the Si pn junction present below the Al or Al-Si film. For this reason, 
the heating treatment should preferably be conducted at a temperature as 
low as possible. However, in order that Al or Al-Si can be transformed 
into monocrystalline state, the Al atoms have to become flowable by 
thermal energy. Consequently the heating method is preferably such as to 
heat the Al or Al-Si alone but not the Si substrate present thereunder. 
Heating in vacuum can be achieved, in a scanning .mu.-RHEED microscope 
shown in FIG. 3, by a heater positioned behind the substrate. 
In case of heat treatment in vacuum, there is preferably employed high 
vacuum of ca. 1.times.10.sup.-6 Torr or lower, in order to suppress the 
oxidation of Al surface. In FIG. 3 there are shown an electron gun 20; an 
electron beam 21; a diffracted electron beam 22; a fluorescent plate 23; 
optical fibers 24, 24', 24"; photomultipliers 25, 25', 25"; diffraction 
spot intensity signals 26, 26', 26" converted into electrical signals; a 
scanning signal 27; a cathode ray tube (CRT) 28; a secondary electron 
signal 29; a secondary electron detector 30; a specimen 31; a vacuum 
chamber 34; and a vacuum system 35. 
A specimen as shown in FIG. 1A is placed in the vacuum chamber 34, and is 
heated from the back by a heater 32. The temperature of the specimen is 
measured from the back thereof by a thermocouple 33. The heating may also 
be conducted by a lamp or a laser instead of the heater. The vacuum 
chamber 34 is evacuated by the vacuum system 35, to a level of 
5.times.10.sup.-10 Torr prior to heating, and to a level of 
5.times.10.sup.-9 -5.times.10.sup.-8 Torr during the heating. Though a 
higher vacuum level is preferable, the conversion to monocrystalline state 
by heating is still possible even at a higher pressure than stated above. 
The transformation of aluminum to the monocrystalline state takes place 
when the temperature measured by the thermocouple 32 is about 550.degree. 
C. or higher. 
In the following there will be explained a rapid thermal annealer (RTA) 
which can be employed in the present invention. 
The RTA can heat solely the wafer surface within a short period, thereby 
minimizing the reaction of Al or Al-Si with the Si substrate. 
FIG. 4 shows an example of the RTA. A substrate 200 is supported by fingers 
205 of a quartz substrate support 201. A quartz tube 202 may have a 
circular or square cross section, or may be replaced by a metal tube, such 
as a stainless steel tube, equipped with a quartz window. A linear lamp 
203, of which light is reflected by a reflector 204 and irradiates the 
specimen 200 whose Al deposition face is directed to said lamp, may be 
composed of a halogen lamp, tungsten lamp, a Xe lamp or a Xe-Hg lamp. In 
the present example there is employed a halogen lamp of a higher heating 
speed. 
At the heating, the interior of the quartz reaction tube is maintained at a 
low pressure or at atmospheric pressure. The internal atmosphere can be 
H.sub.2, N.sub.2 or Ar, or a mixture thereof. The H.sub.2 atmosphere is 
most preferred because highly pure gas, low in contents of moisture and 
oxygen, is available. 
The transformation of Al to monocrystalline state took place when heating 
was conducted at ca. 550.degree. C. or higher with the RTA of the 
above-explained structure. Heating from the room temperature to the heat 
treating temperature took about 5 to 30 seconds, and the heat treatment 
was conducted for about 10 seconds to 1 minute. No difference was observed 
in the area of transformation to monocrystalline state, within the 
above-mentioned range of temperature increasing time or heat treating 
period. 
A heating temperature of ca. 550.degree. C. or higher was necessary for the 
transformation to monocrystalline state. The substrate temperature was 
measured at the surface thereof, by means of a radiation thermometer 
utilizing PbS as a detector. 
In the following there will be explained laser heating applicable to the 
present invention. 
Laser heating can also heat the substrate surface only, and has an 
advantage of providing a wider monocrystalline area than with the RTA. 
The laser employable for this purpose can be an argon ion laser 
(hereinafter represented as Ar laser), a krypton ion laser (hereinafter 
represented as Kr laser), a He-Ne laser, a CO.sub.2 laser, a YAG laser, an 
excimer laser such as ArF, KrF, XeF or XeCI laser with an output of 
several to twenty watts. The oscillation frequency can be continuous 
oscillation or pulsed oscillation of ca. 10-100 Hz. 
The laser heating is featured by a fact that the monocrystalline area can 
be enlarged by scanning of the specimen with the laser beam. Such 
enlargement of the monocrystalline area by laser scanning will be 
explained in the following. 
There is employed a specimen on which the first Al 62 is formed with a 
width L10 on the semiconductor substrate 61, while the second Al 63 is 
formed over the entire surface of said substrate, as shown in FIGS. 5A, 
5B, 6A, 6B, 7A or 7B. On said second Al 63, there may be formed an 
insulation film 65 over the entire surface as shown in FIG. 5B or 6B. 
Otherwise an insulation film 66 may be formed in stripes, as shown in 
FIGS. 7A and 7B, substantially perpendicularly to the lines of the first 
Al 62. 
Said specimen is scanned with a laser beam 67 in reciprocating manner as 
indicated by a line 68 in FIG. 5A, 5B or 7A, or in one direction as 
indicated by a line 69 in FIG. 6A, 6B or 7B. In case of FIG. 5A, 5B or 7A, 
the laser beam is obtained from a continuously oscillated Ar laser or a 
pulse oscillated XeCl excimer laser and is focused to about 20-100 .mu.m. 
In case of FIG. 6A, 6B or 7B, a laser beam of a circular cross section is 
converted into a parallel beam 71 by an optical system 70 employing a 
cylindrical lens. 
The scanning direction of such laser beam or parallel laser beam is 
substantially perpendicular to the line of the first Al 62, as shown in 
FIG. 5A, 5B, 6A, 6B, 7A or 7B. 
In a specimen as shown in FIG. 6A, in which a thermally oxidized SiO.sub.2 
layer of a thickness of ca. 7000 .ANG. is formed on the Si substrate, with 
a line width L10 of ca. 10 .mu.m for the first Al 62 and with a thickness 
of ca. 5000 .ANG. A for the second Al 63, the beam from an Ar laser is 
converted into a parallel beam 71 and the specimen is scanned in one 
direction 69 with a speed of ca. 1 cm/sec. The rear face of the specimen 
is not heated. 
The Ar laser has an output of ca. 20-50 W, with a power density of ca. 
50-200 Kw/cm.sup.2 on the specimen. The atmosphere of laser heating is 
H.sub.2 gas of 1 atmosphere. 
The substrate temperature is measured at the position of irradiation, with 
a radiation thermometer employing a PbS detector. The transformation to 
the monocrystalline state of Al on the first insulation film takes place 
when the substrate temperature is ca. 500.degree. C. or higher. 
In the following there will be explained heating with a linear heater, 
applicable to the present invention. 
FIG. 8 illustrates the method of heating with a linear heater. The 
substrate 82 to be heated is placed on a substrate support 81, made of 
carbon. On said substrate 82 there is positioned a linear heater 83, which 
is also of carbon and energized by a power source 84. The substrate 
support 81 is also heated by a heater (not shown) provided at the bottom 
side of said support. The linear heater 83 moves in a direction 85. 
The atmosphere at heating may assume any pressure from vacuum to 
atmospheric pressure, and is preferably composed of H.sub.2, N.sub.2 Ar or 
a mixture thereof in order to prevent the oxidation of Al surface. Single 
crystal formation is possible also in vacuum, but the structure of the 
apparatus is simpler when the atmospheric pressure is employed. 
The transformation of the second Al to monocrystalline state takes place 
immediately below the linear heater, when the substrate temperature 
immediately below the linear heater is ca. 550.degree. C. or higher. The 
substrate temperature is measured with a radiation thermometer employing a 
PbS detector. 
The feature of heating with such linear heater lies, as in the laser 
heating, in a fact that the area of monocrystalline transformation can be 
expanded by scanning the heated area. 
In the following there will be explained lamp heating, applicable to the 
present invention. 
FIG. 9 illustrates the heating method with a lamp, wherein a substrate 92 
to be heated is placed on a substrate support 91, made of carbon. A lamp 
93 can be a mercury lamp, a Hg-Xe lamp, a Xe lamp or a Xe flash lamp, and 
preferably has a linear structure. The light from the lamp 93 is condensed 
by a reflector 94 so as to form a line on the substrate surface. The 
substrate support 91 is also heated by a heater (not shown) provided on 
the bottom side thereof. The heated area 95 moves on the substrate in a 
direction 96, by the movement of the lamp. The atmosphere at heating may 
assume any pressure from atmospheric pressure to vacuum, and is preferably 
composed of H.sub.2, N.sub.2, Ar or a mixture thereof, in order to prevent 
oxidation of the Al surface. The single crystal formation is possible also 
in vacuum, but the atmospheric pressure allows the employment of a simpler 
structure of the apparatus. 
The transformation of the second Al to monocrystalline state takes place in 
the heated linear area 95, when the substrate temperature therein is ca. 
550.degree. C. or higher. The substrate temperature is measured by a 
radiation thermometer employing a PbS detector. 
In the following there will be explained heating with high frequency, 
applicable in the present invention. 
FIG. 10 illustrates the heating method by high frequency heating. A 
substrate 103 to be heated is placed on a substrate support 101, made of 
carbon. Quartz plates 102 are provided with a gap therebetween. The 
substrate support bearing the substrate thereon as shown in FIG. 10 is 
heated by a high frequency coil (not shown) positioned therearound. Since 
the quartz plates 102 are not heated by the high frequency, a part 104 of 
the substrate is heated to a highest temperature. 
By a wafer movement in a direction 105, the high temperature area 104 moves 
on the wafer. The atmosphere at heating may assume any pressure from 
atmospheric pressure to vacuum, and is preferably composed of H.sub.2, 
N.sub.2, Ar or a mixture thereof, in order to prevent oxidation of the Al 
surface. The single crystal formation is also possible in vacuum, but the 
atmospheric pressure allows to simplify the structure of the apparatus. In 
the following embodiment, the pressure of the atmosphere is atmospheric 
pressure. 
The transformation of the second Al to monocrystalline state takes place in 
the linear heated area 104, when the substrate temperature therein is ca. 
550.degree. C. or higher. The substrate temperature is measured with a 
radiation thermometer employing a PbS detector. 
In the following there will be explained heating with an electron beam, 
applicable to the present invention. 
FIG. 11 illustrates the heating method with an electron beam. An electron 
beam 113 from a filament 112 is focused in the form of a line on a 
substrate 111 to be heated, by means of a condensing coil 115, a scanning 
coil and deflecting plates 115'. Thus, on the substrate, a linear portion 
114 is heated to a high temperature. With a wafer movement in a direction 
116, the heated area 114 also moves on the wafer. 
The atmosphere of heating is preferably high vacuum in order to prevent 
oxidation of the Al surface. The transformation of Al to monocrystalline 
state takes place at a pressure of ca. 10.sup.-6 Torr or lower. The moving 
speed of the substrate is ca. 0.5-10 cm/min. The substrate surface 
temperature in the heated area is measured with a radiation thermometer 
employing a PbS detector, and the monocrystalline transformation of Al 
takes place when said temperature is ca. 450.degree. C. or higher. 
In the following there will be explained the method of observation of a 
monocrystalline area with a scanning .mu.-RHEED microscope shown in FIG. 
3. 
The scanning .mu.-RHEED microscope is disclosed in Extended Abstracts of 
the 21st Conference on Solid State Devices and Materials (1989) p.217 and 
Japanese Journal of Applied Physics Vol. 28, No. 11(1989) L2075. The 
conventional RHEED (reflection high energy electron diffraction) method is 
to irradiate the specimen surface with an electron beam at a shallow angle 
of 2-3.degree. and to evaluate the crystallinity of the specimen surface 
from the diffraction pattern generated by the diffracted electron beam. It 
can only provide averaged information of the specimen surface, because the 
diameter of the electron beam is as large as 100 to several hundred .mu.m. 
In the scanning .mu.-RHEED microscope shown in FIG. 3, the diameter of the 
electron beam from the electron gun 20 is reduced to 0.1 .mu.m, and the 
electron beam diffraction pattern from a specified small area on the 
specimen surface can be observed on the fluorescent plate 23. It is also 
possible to two-dimensionally scan the specimen surface with the electron 
beam 21, to guide the diffracted electron beam 22 to the fluorescent plate 
23, to utilize the intensity change of an arbitrary diffraction spot on 
the diffraction pattern as image signals 26, 26', 26", and to obtain a 
two-dimensional image (scanning .mu.-RHEED image) of the specimen surface 
by the diffraction spot intensity change on the CRT 28. In this method, 
observation of a scanning .mu.-RHEED image employing different diffraction 
spots A, C on the diffraction pattern as shown in FIG. 12 allows to 
separately display the crystal grains in which the lattice planes are 
parallel to the specimen surface, for example to a plane (100) but are 
rotated in said plane. Said diffraction spot A is on a line l on which a 
plane of the diffraction spots and a sagittal plane of the incident 
electron beam perpendicularly cross, while the diffraction spot C is not 
on said line l. For example, as shown in FIG. 13, if a lattice plane (100) 
parallel to the specimen surface has mutual rotation in crystal grains x, 
y in said plane, the scanning .mu.-RHEED image utilizing the diffraction 
spot A shows both the crystal grains x, y as high intensity areas, but the 
image utilizing the spot C shows only the crystal grain x as the high 
intensity area. Consequently observation of the scanning .mu.-RHEED image 
utilizing the diffraction spots A and C as shown in FIG. 12 allows to 
identify whether the crystal in the observed area is polycrystalline 
including in-plane rotation or monocrystalline. 
In the following there will be explained examples of monocrystalline 
transformation of Al on SiO.sub.2 by a heat treatment. 
There were employed the following specimens. 
There were prepared specimens, bearing non-monocrystalline Al formed on a 
monocrystalline seed pattern as shown in FIG. 2A, 2B or 2C. In a checkered 
pattern shown in FIG. 2A, L1 was selected in a range of 0.5-20 .mu.m. In a 
via hole pattern shown in FIG. 2B, L3 was selected not exceeding 20 .mu.m. 
In a line-and-space pattern shown in FIG. 2C, L5 was selecting not 
exceeding 20 .mu.m. 
Such specimen, when evaluated by X-ray diffraction, only showed a peak of 
Al(111). Also the observation with the conventional RHEED apparatus with 
an electron beam diameter of 100 .mu.m to 1 mm.phi. provided a circular 
pattern shown in FIG. 14A. Consequently the Al deposited over the entire 
area was identified as polycrystalline with an orientation (111). 
Such X-ray diffraction and conventional RHEED observation proved the 
polycrystalline state, but were unable to identify the size of the crystal 
grains. Observation with a scanning .mu.-RHEED microscope with an electron 
beam diameter reduced to 0.1 .mu.m.phi. provided a spot pattern shown in 
FIG. 14B though the intensity was weak. Also FIG. 15A shows the result of 
observation of the scanning .mu.-RHEED image, utilizing the spot intensity 
variation on the diffraction pattern, wherein hatched areas indicate areas 
with a high diffraction spot intensity, while a white area indicates an 
area of weak intensity. 
The size of the hatched areas suggests that the size of the crystal grains 
is in the order of several to ten microns. 
After the same specimen was heated in the scanning .mu.-RHEED microscope 
for 15 minutes at 550.degree. C., it was subjected to observation of the 
electron beam diffraction pattern and the scanning .mu.-RHEED image. The 
electron beam diffraction pattern showed spots of higher intensity than 
those before heating, as shown in FIG. 14B. The spots in FIG. 14B were 
identified as a diffraction pattern generated when the electron beam is 
introduced from a direction [101] into the Al(111) plane. FIGS. 15B and 
15C indicate the results of observation of the scanning .mu.-RHEED image, 
utilizing the intensity of a spot A (111 diffracted spot) and a spot C 
(202 diffracted spot) on the diffraction pattern in FIG. 14B. In any 
position on the specimen surface, the spots A, C were both strong, 
suggesting that all the observed area has turned into monocrystalline 
state. It was therefore confirmed that an Al film even existing on 
SiO.sub.2 could be transformed into monocrystalline state by heat 
treatment if monocrystalline Al was present under said Al film. The 
specimen after heat treatment, when evaluated by X-ray diffraction, showed 
only a peak of Al(111), and observation with the conventional RHEED 
apparatus provided a spot pattern indicating monocrystalline state as 
shown in FIG. 14B. 
The monocrystalline transformation was also experimented with another 
specimen, which, as shown in FIG. 16A, is composed of an Si substrate 
bearing thereon a thermal silicon oxide film of a thickness of 1 .mu.m and 
having apertures formed by dry etching in said film to expose the Si 
surface. 
In an area I there is formed a checker pattern, a via hole pattern or a 
line-and-space pattern as shown in FIG. 2A, 2B or 2C, while an area II is 
entirely covered by SiO.sub.2 without such pattern. The substrate with 
SiO.sub.2 pattern as shown in FIG. 16A was at first subjected to 
deposition of the first Al selectively in the apertures by the CVD method 
utilizing DMAH and H.sub.2, and, after a surface modifying step, the 
second Al was deposited over the entire surface of the substrate. 
The evaluation by X-ray diffraction thereafter showed only an Al(111) peak. 
Also observation with the conventional RHEED apparatus with an electron 
beam diameter of 100 .mu.m-1 mm.phi. provided a ring-shaped electron beam 
diffraction pattern as shown in FIG. 14A. Consequently the aluminum 
deposited on the entire surface was identified as polycrystals with an 
orientation (111). Also observation with the scanning .mu.-RHEED 
microscope with an electron beam diameter of 0.1 .mu.m provided electron 
beam diffracted spots as shown in FIG. 14B though the intensity was weak. 
The scanning .mu.-RHEED image obtained by utilizing the diffraction spot 
intensity on the spot pattern suggested that the specimen consisted of 
crystal grains of a size of several to ten microns, as shown in FIG. 15A. 
Said specimen was heated in the scanning .mu.-RHEED microscope for 15 
minutes at 645.degree. C., and was subjected to the observation of the 
electron beam diffraction pattern and the scanning .mu.-RHEED image. The 
electron beam diffraction provided a spot pattern as shown in FIG. 14B, 
with an increased intensity. Said pattern was identified to be generated 
when the electron beam was introduced from a direction [101] into the 
Al(111) plane. FIGS. 16B and 16C show the results of observation of the 
scanning .mu.-RHEED image, utilizing the intensity of a diffraction spot A 
(111 diffracted spot) and a diffraction spot C (202 diffracted spot) in 
the diffraction pattern shown in FIG. 14B. In FIGS. 16B and 16C, hatched 
areas indicate areas with high diffraction spot intensity, corresponding 
to (111) single crystal. FIGS. 16B and 16C suggest that the 
monocrystalline area extended by about 10 82 m from the area I including 
the apertures. It was therefore confirmed that the transformation to 
monocrystalline state by heat treatment extended by about 10 .mu.m from 
the patterned area I, even in the absence of exposed Si under the Al film. 
Said transformation extended for about 10 .mu.m from the area I in any of 
(a) checkered pattern, (b) via hole pattern, and (c) line-and-space 
pattern shown in FIG. 2. 
Within the SiO.sub.2 thickness from 500 .ANG. to 1 .mu.m, the area of 
transformation to monocrystalline state by heat treatment was same as in 
FIGS. 16B and 16C, regardless of the thickness of SiO.sub.2. Also within a 
range of 500 .ANG. to 1 .mu.m of the thickness of the Al film deposited on 
SiO.sub.2, the area of transformation was the same as in FIGS. 16B and 
16C. 
In the heating method in which the heated area moves on the substrate, as 
in the laser heating, heating with linear heater, high frequency heating 
or electron beam heating, the area of monocrystalline transformation was 
measured in the following manner. 
In FIG. 17A, an area III is provided with a checkered pattern, a via hole 
pattern or a line-and-space pattern as in the area I in FIG. 16A, while an 
area IV is provided with the first insulation film. The first Al and the 
second Al were formed on such substrate. 
The second Al in deposited state was polycrystals with grains of several to 
ten microns in size. 
With a laser beam as shown in FIG. 5, the scanning is conducted in a 
direction x shown in FIG. 17A. Also in case of heating with a flat laser 
beam as shown in FIG. 6, or in case of lamp heating, high frequency 
heating or electron beam heating, the heated area is moved in said 
direction x. 
FIGS. 17B and 17C show the results of observation with the scanning 
.mu.-RHEED microscope after the heat treatment. The electron beam 
diffraction pattern by said microscope provided spots as shown in FIG. 
14B, with increased intensity than before the heat treatment. The scanning 
.mu.-RHEED observation, utilizing the intensity of a diffraction spot A 
(111 diffracted spot) and a diffraction spot C (202 diffracted spot) in 
the pattern shown in FIG. 14B provided images shown in FIGS. 16B and 16C, 
wherein hatched areas indicate areas with high spot intensity. An area, 
where both spots A and C have high intensity, corresponds to (111) single 
crystal. 
In FIG. 17C, a distance L8 indicates the area transformed to 
monocrystalline state by heat treatment. 
FIG. 17A illustrates the pattern of insulation film, corresponding to FIGS. 
17B and 17C. The above-mentioned specimen contains a stripe of the first 
Al in the area III, and the heated area is moved in the direction x shown 
in FIG. 17A. Though FIG. 17C shows L8 in a size of about 10 .mu.m, but L8 
reached ca. 1 cm in case of laser annealing, heating with linear heater, 
lamp heating, high frequency heating or electron beam heating. 
It was therefore confirmed that the transformation to monocrystalline state 
extended by about 1 cm from the patterned area, even in the absence of 
exposed Si under the Al film. 
Electromigration resistance was measured on the Al film subjected to 
monocrystalline transformation on SiO.sub.2. The conventional Al or Al-Si 
wiring obtained by sputtering shows an average service life of 
1.times.10.sup.2 -10.sup.3 hours with a wiring cross section of 1 
.mu.m.sup.2, in a current test of 1.times.10.sup.6 A/cm.sup.2 at 
250.degree. C. On the other hand, the moncrystalline Al wiring of the 
present invention provided a service life of 10.sup.4 -10.sup.5 hours with 
a cross section of 1 .mu.m.sup.2 in the above-mentioned test. Also a 
wiring with a width of 0.8 .mu.m and a thickness of 0.3 .mu.m provided an 
average service life of 10.sup.3 -10.sup.4 hours in said test. 
Also the percentage of wiring breakage was measured by patterning the 
monocrystalline Al into a width of ca. 1 .mu.m, depositing a silicon 
nitride film thereon by a CVD method, and applying stress for 1000 hours 
at 150.degree. C. In the conventional sputtered Al wiring of a length of 1 
mm, the percentage of breakage in 1000 lines was 10-20%, but, in the 
monocrystalline Al wiring of the present invention, no breakage was 
observed in 1000 lines. 
In this manner the monocrystalline Al wiring can drastically improve the 
resistance to electromigration and stress migration. 
Still another preferred embodiment of the present invention utilizes 
monocrystalline Al formed in a via hole which is formed in an insulation 
film as a seed crystal, and converts non-monocrystalline Al in other areas 
into monocrystalline state by heating. It is particularly preferable, 
after formation of monocrystalline Al by selective deposition of Al in the 
via hole, to non-selectively deposit Al also on the insulation film, and, 
after ion implantation, to apply heat treatment thereby converting Al on 
the insulation film into monocrystalline state. Such method allows to 
obtain a flat Al film, without formation of a recess in the Al film on the 
via hole. 
The non-monocrystalline Al film is once converted into amorphous or 
microcrystalline state, and is then transformed into monocrystalline state 
by heating, employing the monocrystalline Al as a seed crystal. 
According to the present invention, the non-monocrystalline Al film, formed 
as explained above, is subjected to the implantation of H.sup.+, Ar.sup.+, 
Si.sup.+ or Al.sup.+ ions by a known ion implanting method. Although other 
ions may also be employed, the abovementioned four ions are preferably 
employed in order not to deteriorate the reliability of the Al or Al-Si 
wirings for ULSI, and AL.sup.+ or H.sup.+ ions are most preferable. 
Said H.sup.+, Al.sup.+, Ar.sup.+ or Si.sup.+ ions are preferably implanted 
with an acceleration voltage of ca. 50 kV or higher and with a dose of ca. 
1.times.10.sup.15 cm.sup.-2 or higher. Thus the second Al can be converted 
into amorphous or microcrystalline state, even when said second Al has a 
thickness of ca. 5000 .ANG.. 
The ion implantation transforms Al, which is polycrystalline when 
deposited, into amorphous state. Since the Al atoms can more easily flow 
in the amorphous state than in the polycrystalline state, the 
transformation to monocrystalline state is achieved at a lower temperature 
than in the heat treatment at the polycrystalline state. It is already 
known that a semiconductor having covalent bonds such as Si or GaAs on an 
insulating film is transformed into monocrystalline state by heat 
treatment. For example in a method called single phase epitaxy (SPE), 
silicon deposited on a monocrystalline Si substrate is converted into 
amorphous state by ion implantation, and is then converted to 
monocrystalline state by heat treatment for example in an electric oven. 
The present invention is based on a finding that even a metal film such as 
of Al present on an insulating film, after conversion into amorphous or 
microcrystalline state by ion implantation, can be transformed into 
monocrystalline state at a relatively low temperature. It is already known 
that an Al or Al-Si film on an insulating film can be grown into a 
polycrystalline film consisting of crystal grains of several microns by 
heat treatment of ca. 450.degree. C. However transformation to the 
monocrystalline state by heat treatment has been impossible because the 
method of Al deposition for obtaining the structure shown in FIG. 1A has 
not been known, and also because the selectively deposited Al (first Al in 
FIG. 1A) has not been monocrystalline. The present invention has enabled, 
for the first time, to transform an Al film (second Al in FIG. 1A) on an 
insulating film into monocrystalline state by heat treatment after ion 
implantation, if selectively grown monocrystalline Al (first Al in FIG. 
1A) is present thereunder. 
The semiconductor substrate is most preferably a Si substrate, but it may 
also be composed of GaAs, InP or Ge. The cross sectional structure of the 
specimen after formation of Al of Al-Si is as shown in FIG. 1A. 
In the following embodiments, the transformation to monocrystalline state 
is realized even if the second Al becomes thinner or thicker on the first 
Al. Also an insulation film 5 may be present on the second Al film as 
shown in FIG. 1B. Said insulation film 5 may be composed of SiO.sub.2 
obtained by normal pressure CVD, phosphor-doped oxide film (PSG), 
boron-doped oxide film (BSG), phosphor- and boron-doped oxide film (BPSG), 
silicon nitride film (SiN) obtained by low pressure CVD, or silicon 
nitride film obtained by ECR. 
The method of heat treatment for monocrystalline transformation is same as 
explained in the foregoing. 
In the following there will be explained examples of monocrystalline 
transformation of Al, including a step of conversion to amorphous or 
microcrystalline state. 
Specimens were prepared with monocrystalline seed patterns as explained 
before, namely a checkered pattern as shown in FIG. 2A with L1 within a 
range of 0.5-20 .mu.m, or a via hole pattern as shown in FIG. 2B with L3 
of 20 .mu.m or less, or a line-and-space pattern with L5 of 20 .mu.m, and 
also with non-monocrystalline Al on such monocrystalline seed pattern. 
Said specimens, when evaluated by X-ray diffraction, showed only a peak of 
Al(111). Also observation with the conventional RHEED apparatus with an 
electron beam diameter of 100 .mu.m to 1 mm.phi. provided a circular 
electron beam diffraction pattern as shown in FIG. 14A. Thus the Al 
deposited over the entire surface was identified as polycrystals with an 
orientation (111). 
Such X-ray diffraction and conventional RHEED observation proved the 
polycrystalline state, but were unable to identify the size of the crystal 
grains. Observation with a scanning .mu.-RHEED microscope with an electron 
beam diameter reduced to 0.1 .mu.m.phi. provided a spot pattern shown in 
FIG. 14B though the intensity was weak. Also FIG. 15A shows the result of 
observation of the scanning .mu.-RHEED image, utilizing the spot intensity 
variation on the diffraction pattern, wherein hatched areas indicate areas 
with a high diffraction spot intensity, while a white area indicates an 
area of weak intensity. 
The size of the hatched areas suggests that the size of the crystal grains 
is in the order of several to ten microns. 
Said specimen was implanted for example with Al.sup.+ ions with an 
acceleration voltage of 50 kV and with a dose of 1.times.10.sup.16 
/cm.sup.2. 
Said ion implantation caused transformation of the second Al into amorphous 
or microcrystalline state. Said transformation was confirmed in the 
following manner. The X-ray diffraction showed a diffraction peak of 
Al(111) in the deposited state, but, after ion implantation, no longer 
showed diffraction peak for aluminum. Also observation of the electron 
beam diffraction pattern by the conventional RHEED apparatus did not show 
circular nor spot pattern but so-called hallow pattern, indicating that 
the Al or Al-Si film was transformed by the ion implantation into a state 
which is not monocrystalline nor polycrystalline but amorphous or 
microcrystalline. 
After the same specimen was heated in the scanning .mu.-RHEED microscope 
for 15 minutes at 250.degree. C., it was subjected to observation of the 
electron beam diffraction pattern and the scanning .mu.-RHEED image. The 
electron beam diffraction pattern showed spots of higher intensity than 
those before heating, as shown in FIG. 14B. The spots in FIG. 14B were 
identified as a diffraction pattern generated when the electron beam is 
introduced from a direction [101] into the Al(111) plane. FIGS. 15B and 
15C indicate the results of observation of the scanning .mu.-RHEED image, 
utilizing the intensity of a spot A (111 diffracted spot) and a spot C 
(202 diffracted spot) on the diffraction pattern in FIG. 14B. In any 
position on the specimen surface, the spots A, C were both strong, 
suggesting that all the observed area has turned into monocrystalline 
state. It was therefore confirmed that an Al film even existing on 
SiO.sub.2 could be transformed into monocrystalline state by heat 
treatment, if monocrystalline Al was present under said Al film. The 
specimen after heat treatment, when evaluated by X-ray diffraction, showed 
only a peak of Al(111), and observation with the conventional RHEED 
apparatus provided a spot pattern indicating monocrystalline state as 
shown in FIG. 14B. 
The monocrystalline transformation was also experimented with another 
specimen, which, as shown in FIG. 16A, is composed of an Si substrate 
bearing thereon a thermal silicon oxide film of a thickness of 1 .mu.m and 
having apertures formed by dry etching in said film to expose the Si 
surface. 
In an area I there is formed a checkered pattern, a via hole pattern or a 
line-and-space pattern as shown in FIG. 2A, B or C, while an area II is 
entirely covered by SiO.sub.2 without such pattern. The substrate with 
SiO.sub.2 pattern as shown in FIG. 16A was at first subjected to 
deposition of the first Al selectively in the apertures by the CVD method 
utilizing DMAH and H.sub.2, and, after a surface modifying step, the 
second Al was deposited over the entire surface of the substrate. 
The evaluation by X-ray diffraction thereafter showed only an Al(111) peak. 
Also observation with the conventional RHEED apparatus with an electron 
beam diameter of 100 .mu.m-1 mm.phi. provided a ring-shaped electron beam 
diffraction pattern as shown in FIG. 14A. Consequently the aluminum 
deposited on the entire surface was identified as polycrystals with an 
orientation (111). Also observation with the scanning .mu.-RHEED 
microscope with an electron beam diameter of 0.1 .mu.m provided electron 
beam diffracted spots as shown in FIG. 14B though the intensity was weak. 
The scanning .mu.-RHEED image obtained by utilizing the diffraction spot 
intensity on the spot pattern suggested that the specimen consisted of 
crystal grains of a size of several to ten microns, as shown in FIG. 15A. 
Said specimen was heated in the scanning .mu.-RHEED microscope for 
15minutes at 260.degree. C., and was subjected to the observation of the 
electron beam diffraction pattern and the scanning .mu.-RHEED image. The 
electron beam diffraction provided a spot pattern as shown in FIG. 14B, 
with an increased intensity. Said pattern was identified to be generated 
when the electron beam was introduced from a direction [101] into the 
Al(111) plane. FIGS. 16B and 16C show the results of observation of the 
scanning .mu.-RHEED image, utilizing the intensity of a diffraction spot A 
(111 diffracted spot) and a diffraction spot C (202 diffracted spot) in 
the diffraction pattern shown in FIG. 14B. In FIGS. 16B and 16C, hatched 
areas indicate areas with high diffraction spot intensity, corresponding 
to (111) single crystal. FIGS. 16B and 16C suggest that the 
monocrystalline area extended by about 10 .mu.m from the area I containing 
the apertures. It was therefore confirmed that the transformation to 
monocrystalline state by heat treatment extended by about 10 .mu.m from 
the patterned area I, even in the absence of exposed Si under the Al film. 
Said transformation extended for about 10 .mu.m from the area I in any of A 
checkered pattern, B via hole pattern, and C line-and-space pattern shown 
in FIG. 2. 
Within the SiO.sub.2 thickness from 500 .ANG. to 1 .mu.m, the area of 
transformation to monocrystalline state by heat treatment was same as in 
FIGS. 16B and 16C, regardless of the thickness of SiO.sub.2. Also with a 
range of 500 .ANG. to 1 .mu.m of the thickness of the Al film deposited on 
SiO.sub.2, the area of transformation was same as in FIGS. 16B and 16C. 
Electromigration resistance was measured on the Al film subjected to 
monocrystalline transformation on SiO.sub.2. The conventional Al or Al-Si 
wiring obtained by sputtering shows an average service life of 
1.times.10.sup.2 -10.sup.3 hours with a wiring cross section of 1 
.mu.m.sup.2, in a current test of 1.times.10.sup.6 A/cm.sup.2 at 
250.degree. C. On the other hand, the monocrystalline Al wiring of the 
present invention provided a service life of 10.sup.4 -10.sup.5 hours with 
a cross section of 1 .mu.m.sup.2 in the above-mentioned test. Also a 
wiring with a width of 0.8 .mu.m and a thickness of 0.3 .mu.m provided an 
average service life of 10.sup.3 -10.sup.4 hours in said test. 
Also the percentage of wiring breakage was measured by patterning the 
monocrystalline Al into a width of ca. 1 .mu.m, depositing a silicon 
nitride film thereon by a CVE method, and applying stress for 1000 hours 
at 150.degree. C. In the conventional sputtered Al wiring of a length of 1 
mm, the percentage of breakage in 1000 lines was 10-20%, but, in the 
monocrystalline Al wiring of the present invention, no breakage was 
observed in 1000 lines. 
In this manner the monocrystalline Al wiring obtained after conversion to 
amorphous or microcrystalline state can drastically improve the resistance 
to electromigration and stress migration. 
EXAMPLE 1 
The specimen used in the measurement, having a cross-sectional structure as 
shown in FIG. 1A, was prepared in the following manner. 
An Si wafer was subjected to thermal oxidation at 1000.degree. C. by 
hydrogen combustion (H.sub.2 : 4 1/min., O.sub.2 : 2 1/min.). The surface 
orientation of the Si wafer was (100) or (111). The entire wafer was 
coated with photoresist and was exposed to a desired pattern by an 
exposure apparatus. After the photoresist was developed, reactive ion 
etching was conducted, utilizing the photoresist as a mask, to etch the 
underlying SiO.sub.2, thereby locally exposing the Si surface. 
Then an Al film was deposited by a low pressure CVD method, employing 
dimethylaluminum hydride and hydrogen, with a deposition temperature of 
ca. 270.degree. C. and a pressure of ca. 1.5 Torr in the reactor tube. At 
first selective Al deposition (first Al) was conducted solely on the 
exposed Si surface, then a surface modifying step was conducted by 
generating plasma in the low pressure CVD apparatus when the Al film 
thickness became equal to the SiO.sub.2 film thickness, and Al (second Al) 
was deposited on the entire surface. 
Following SiO.sub.2 patterns and Al film thicknesses were employed on the 
specimens. The SiO.sub.2 film thickness was varied in 5 levels of 1000, 
2500, 5000, 7500 and 10000 .ANG.. The checkered pattern shown in FIG. 2A 
was used on the Si wafer, with size L1 varied in 8 levels of 0.25, 0.5, 1, 
2, 3, 5, 10 and 20 .mu.m. Thickness of the Al film deposited on the entire 
surface (second Al film 4 in FIG. 1) was varied in 5 levels of 1000, 2500, 
5000, 7500 and 10000 .ANG.. Each of the above-mentioned specimens was 
subjected to the observations of electron diffraction pattern and scanning 
.mu.-RHEED image in the scanning .mu.-RHEED microscope. Then the specimen 
was heated by energizing the heater, and the above-mentioned observations 
were conducted again. The heating in the scanning .mu.-RHEED microscope 
was varied in 5 levels of (1) 550.degree. C, 6 hrs., (2) 600.degree. C., 2 
hrs., (3) 645.degree. C. 15 min., (4) 670.degree. C., 5 min., and (5) 
700.degree. C., 5 min. 
In the X-ray diffraction conducted after Al deposition but before loading 
in the scanning .mu.-RHEED microscope, all the specimens showed only an Al 
(111) peak, regardless of the SiO.sub.2 thickness, size of the checkered 
pattern, or the second Al thickness. Also in the conventional RHEED 
apparatus with an electron beam diameter of 100 .mu.m-1 mm.phi., all the 
specimens showed ring-shaped electron beam diffraction patterns as shown 
in FIG. 14A. It was therefore confirmed that the Al deposited over the 
entire surface was polycrystals with an orientation (111). 
Observation on the scanning .mu.-RHEED microscope with an electron beam 
reduced to a diameter of 0.1 .mu.m provided spot electron beam diffraction 
patterns as shown in FIG. 14B, though the intensity was weak. Also the 
scanning .mu.-RHEED image utilizing the diffraction spot intensity on the 
spot diffraction pattern indicated that the specimens were polycrystals 
consisting of grains of several to ten microns, as shown in FIG. 15A. 
After the heat treatment was conducted in the aforementioned 5 levels in 
the scanning .mu.-RHEED microscope, the electron diffraction pattern and 
the scanning .mu.-RHEED image were observed. All the specimens showed spot 
patterns as shown in FIG. 14B with higher intensity than before heating, 
regardless of the wafer surface orientation, SiO.sub.2 film thickness, 
checkered pattern size or second Al film thickness. The diffractin pattern 
shown in FIG. 14B was identified, from the spot positions, to be generated 
when the electron beam was introduced from a direction [101] into the 
Al(111) plane. The scanning .mu.-RHEED image obtained utilizing the 
intensity of the diffracted spot A (111 diffracted spot) and spot C (202 
diffracted spot) of the diffracted pattern in FIG. 14B was similar to 
those shown in FIGS. 15B and 15C, wherein hatched areas indicate areas of 
high intensity of diffracted spots. The Al film deposited in the 
checker-patterned area showed high intensity both for the spots A and C, 
indicating the transformation to monocrystalline state by the heat 
treatment. Also in observation of the electron diffraction pattern with 
the conventional RHEED apparatus, all the specimens after heat treatment 
showed spot pattern as shown in FIG. 14B, indicating the monocrystalline 
state. 
In heat treatment at 670.degree. C., 5 min. or at 700.degree. C., 5 min., 
the Al film on SiO.sub.2 was transformed into monocrystalline state, but 
showed unevenness in thickness. Also the distribution of elements in the 
direction of depth, measured by electron spectroscopy for chemical 
analysis (ESCA) and Auger dectron spectroscopy (AES) after heat treatment, 
showed diffusion of Al, Si and O at the interface between SiO.sub.2 and 
second Al. Also transformation to monocrystalline state did not take place 
by the heat treatment at 500.degree. C., 6 hrs. 
EXAMPLE 2 
Specimens with a cross-section as shown in FIG. 1A were prepared in the 
same manner as in the example 1, and were heat treated in the scanning 
.mu.-RHEED microscope. 
Diffrerent from the example 1, the via hole pattern shown in FIG. 2B was 
formed on the Si wafer, with L2 varied in 5 levels of 0.25, 0.5, 1, 2 and 
5 .mu.m and L3 in 5 levels of 1, 2, 5, 10 and 20 .mu.m. Thus there were 
prepared 25 via hole patterns obtained by taking all the combinations of 
L2 and L3. The thickness of the SiO.sub.2 film and of the Al film (second 
Al 4 in FIG. 1) deposited over the entire surface were same as those in 
the example 1. 
The specimens prepared as explained above were subjected to heat treatment 
and observations as in the example 1. The heat treating conditions were 
same as those in the example 1. 
Based on the X-ray diffraction, the electron beam diffraction pattern 
obtained by the conventional RHEED apparatus, the electron diffraction 
pattern and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope, the Al deposited on the entire surface (second Al) was 
identified as polycrystals with an orientation (111) consisting of crystal 
grains of several to ten microns, as in example 1. 
After heat treatment in the aforementioned 5 levels in the scanning 
.mu.-RHEED microscope, the specimens were subjected to the observation of 
electron diffraction pattern and the scanning .mu.-RHEED image. All the 
specimens showed, as in the example 1, spot patterns as shown in FIG. 14B 
with a higher intensity than before the heating, regardless of the wafer 
surface orientation, SiO.sub.2 film thickness, via hole dimensions and 
second Al film thickness. The scanning .mu.-RHEED images utilizing the 
intensities of the diffracted spot A (111 diffracted spot) and C (202 
diffracted spot) on the pattern shown in FIG. 14B were similar to those 
shown in FIG. 15B and 15C, as in the example 1. The Al film deposited in 
the area of via hole pattern showed strong intensities for both spots A 
and C, indicating transformation to monocrystalline state by the heat 
treatment. 
As in the example 1, in two heat treating conditions of 670.degree. C., 5 
min. and 700.degree. C., 5 min., the Al film on SiO.sub.2 was transformed 
into monocyrstalline state but showed uneven thickness after the heat 
treatment. Also the measurement of element distribution in the direction 
of depth by ESCA and AES indicated diffusion of Al, Si and O at the 
interface between SiO.sub.2 and second Al film. Also transformation to 
monocrystalline state did not occur in the heat treatment of 500.degree. 
C., 6 hrs. 
EXAMPLE 3 
Specimens with a cross-section as shown in FIG. 1A were prepared in the 
same manner as in the example 1, and were heat treated in the scanning 
.mu.-RHEED microscope. 
Different from the example 1, the line-and-space pattern shown in FIG. 2C 
was formed on the Si wafer, with L4 varied in 5 levels of 0.25, 0.5, 1, 2 
and 5 .mu.m, and L5 in 5 levels of 1, 2, 5, 10 and 20 .mu.m. Thus there 
were prepared 25 line-and-space patterns obtained by taking all the 
combinations of L4 and L5. The thicknesses of the SiO.sub.2 film and of 
the Al film (second Al 4 in FIG. 1) deposited over the entire surface were 
same as those in the example 1. The specimens thus prepared were subjected 
to the heat treatment and observations in the same manner as in the 
example 1. The heat treating conditions were also same as those in the 
example 1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment, the Al deposited on the entire 
surface (second Al) in all the specimens was identified, as in the example 
1, as polycrystals of an orientation (111), consisting of crystal grains 
of several to ten microns. 
After the heat treatment in the aforementioned 5 levels in the scanning 
.mu.-RHEED microscope, there were observed the electron beam diffraction 
pattern and the scanning .mu.-RHEED image. All the specimens showed spot 
diffraction patterns as shown in FIG. 14B, with a higher intensity than 
before heat treatment, regardless of the wafer surface orientation, 
SiO.sub.2 film thickness, line-and-space dimensions or second Al film 
thickness, as in the example 1. The scanning .mu.-RHEED images, obtained 
by utilizing the intensity of the diffraction spot A (111 diffracted spot) 
and spot C (202 diffracted spot) of the diffraction pattern in FIG. 14B 
were similar to those shown in FIGS. 15B and 15C, as in the example 2. 
Thus the Al film deposited on the line-and-space pattern showed high 
intensities both in the diffraction spots A and C, and was therefore 
confirmed to have been transformed into monocrystalline state. 
As in the example 1, in two heat treating conditions of 670.degree. C., 5 
min. and 700.degree. C., 5 min., the Al film on SiO.sub.2 was transformed 
into monocrystalline state but showed uneven thickness after the heat 
treatment. Also the measurement of element distribution in the direction 
of depth by ESCA and AES indicated diffusion of Al, Si and O at the 
interface between SiO.sub.2 and second Al film. Also transformation to 
monocrystalline state did not occur in the heat treatment of 500.degree. 
C., 6 hrs. 
EXAMPLE 4 
Specimens with a cross-section as shown in FIG. 1A were prepared in the 
same manner as in the example 1, and were heat treated in the scanning 
.mu.-RHEED microscope. 
Said specimens were different from those of the example 1 in the pattern 
formed on the Si wafer. As shown in FIG. 16A, the SiO.sub.2 film is 
provided with apertures in an area I but is free from such apertures in an 
area II. The pattern in the area I was the checkered pattern, via hole 
pattern or line-and-space pattern shown in FIG. 2A, 2B or 2C. In the 
checkered pattern, the size L1 was varied in 6 levels of 0.25, 0.5, 1, 2, 
3 and 5 .mu.m. In the via hole pattern, L2 was varied in 5 levels of 0.25, 
0.5, 1, 2 and 5 .mu.m while L3 was varied in 3 levels of 1, 2 and 5 .mu.m, 
and 15 different patterns were prepared by the combinations of L2 and L3. 
In the line-and-space pattern, L4 was varied in 4 levels of 0.25, 0.5, 1 
and 2 .mu.m while L5 in 3 levels of 1, 2 and 5 .mu.m, and 12 different 
patterns were prepared by the combinations of L4 and L5. The thicknesses 
of the SiO.sub.2 film and of the Al film deposited on the entire surface 
(second Al film 4 in FIG. 1A) were same as those in the Example 1. These 
specimens prepared as explained above were subjected to the heat treatment 
and the observations in the same manner as in the example 1. The heat 
treating conditions were same as those in the example 1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment as in the example 1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
After the heat treatment in the aforementioned 5 levels in the scanning 
.mu.-RHEED microscope, there were observed the electron beam diffraction 
pattern and the scanning .mu.-RHEED image. All the specimens showed spot 
diffraction patterns as shown in FIG. 14B, with a higher intensity than 
before the heat treatment, regardless of the wafer surface orientation, 
SiO.sub.2 film thickness, form and dimension of the pattern formed in the 
area I, and second Al film thickness, as in the example 1. The scanning 
.mu.-RHEED images, obtained by utilizing the intensity of the diffraction 
spot A (111 diffracted spot) and spot C (202 diffracted spot) of the 
diffraction pattern in FIG. 14B were similar to those shown in FIG. 16B 
and 16C, wherein hatched areas indicate areas with high intensity of 
dffracted spots, and a (III) monocrystalline state is present where the 
diffracted spots A and C are both strong. As shown in FIGS. 16B and 16C, 
it was found that the area transformed into monocrystalline state extended 
by about 10 .mu.m (corresponding to L6 in FIG. 16C) from the area I 
containing apertures. It was thus confirmed that the monocrystalline 
transformation by heat treatment extended by about 10 .mu.m from the 
patterned area I even in the absence of the exposed silicon under the Al 
film. 
As in the example 1, in two heat treating conditions of 670.degree. C., 5 
min. and 700.degree. C., 5 min., the Al film on SiO.sub.2 was transformed 
into monocrystalline state but showed uneven thickness after the heat 
treatment. Also the measurement of element distribution in the direction 
of depth by ESCA and AES indicated diffusion of Al, Si and O at the 
interface between SiO.sub.2 and second Al film. Also transformation to 
monocrystalline state did not occur in the heat treatment of 500.degree. 
C., 6 hrs. 
EXAMPLE 5 
In the examples 1, 2, 3 and 4, the insulation film was composed of 
SiO.sub.2 obtained by thermal oxidation. In the present example, similar 
specimens as in the foregoing examples were prepared employing, as the 
insulation film, a SiO.sub.2 film obtained by normal pressure CVD 
(hereinafter represented as CVD SiO.sub.2 ), a boron-doped oxide film 
obtained by normal pressure CVD (BSG), a phosphor-doped oxide film 
obtained by normal pressure CVD (PSG), a boron- and phosphor-doped oxide 
film obtained by normal pressure CVD (BPSG), a nitride film obtained by 
plasma CVD (P-SiN), a thermal nitride film (T-SiN), a thermal nitride film 
obtained by low pressure CVD (LP-SiN), and a nitride film obtained by ECR 
apparatus (ECR-SiN). These specimens were subjected to observations of the 
X-ray diffraction pattern and the electron beam diffraction pattern by the 
conventional RHEED apparatus, heat treatment in the scanning .mu.-RHEED 
microscope, and observations of the electron beam diffraction pattern and 
of the scanning .mu.-RHEED image. The thickness of the insulation films 
was selected as ca. 5000 .ANG., except that the thermal nitride film 
(T-SiN) was made with a thickness of ca. 100 .ANG.. The thickness of the 
second Al film was selected as ca. 7500 .ANG.. Formed patterns were same 
as those in the examples 1, 2, 3 and 4. 
There were obtained results similar to those in the examples 1, 2, 3 and 4. 
EXAMPLE 6 
In the examples 1, 2, 3, 4 and 5, the first and second Al films were both 
prepared by low pressure CVD. In the present example, the second Al film 
was prepared by sputtering, but other conditions were maintained same as 
in the examples 1, 2, 3, 4 and 5. 
There were obtained similar results to those in the examples 1, 2, 3, 4 and 
5. 
EXAMPLE 7 
In the examples 1, 2, 3, 4, 5 and 6, the first and second Al films were 
both composed of pure aluminum. In the present example, pure aluminum was 
replaced by Al-Si, with Si content varied as 0.2, 0.5 or 1.0%. 
There were obtained similar results to those in the examples 1, 2, 3, 4, 5 
and 6. 
EXAMPLE A1 
There were prepared specimens same as those in the example 1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment as in the example 1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
These specimens were subjected to heat treatment in the RTA apparatus shown 
in FIG. 4, with substrate temperature varied in 5 levels of 450.degree., 
500.degree., 550.degree., 600.degree. and 650.degree. C., measured with a 
radiation thermometer employing a PbS probe. The temperature raising time 
to the heat treating temperature was 10 seconds, and the heat treating 
time was selected as 10, 20, 40 or 60 seconds. 
Then the heat treated specimens were subjected to the observations of the 
electron beam diffraction pattern and the scanning .mu.-RHEED image in the 
scanning .mu.-RHEED microscope shown in FIG. 3. All the specimens showed 
the spot electron beam diffraction patterns as shown in FIG. 14B, with a 
higher intensity than before the heat treatment, regardless of the Si 
wafer surface orientation, SiO.sub.2 film thickness, checkered pattern 
size or second Al film thickness. The diffraction pattern shown in FIG. 
14B was identified, from the position of the diffraction spots, to be 
generated by the electron beam introduced from a direction [101] into the 
Al(111) plane. The scanning .mu.-RHEED images, utilizing the intensity of 
the diffraction spot A (111 diffracted spot) and spot C (202 diffracted 
spot) on the diffraction pattern in FIG. 14B were similar to those shown 
in FIGS. 15A and 15C, wherein hatched areas indicate those with high 
diffraction spot intensity. The Al film deposited on the checker-patterned 
area showed high intensities for both the spots A and C, indicating 
transformation to the monocrystalline state by heat treatment. Also in the 
observation of the electron diffraction pattern in the conventional RHEED 
apparatus, all the specimens after the heat treatment showed spot patterns 
as shown in FIG. 14B indicating the monocrystalline state. 
In the heat treatment at 650.degree. C., the Al film on SiO.sub.2 was 
transformed into monocrystalline state but showed unevenness in the 
thickness after the heat treatment. Also the measurements of element 
distribution in the direction of depth by electron spectroscopy for 
chemical analysis (ESCA) and Auger electron spectroscopy (AES), the 
specimen heat treated at 650.degree. C. showed diffusion of Al, Si and O 
at the interface between SiO.sub.2 and second Al film. Also transformation 
to monocrystalline state did not occur by the heat treatment at 
500.degree. C. or lower. 
EXAMPLE A2 
Specimens with via hole pattern shown in FIG. 2B were prepared as in the 
example 2, and subjected to heat treatment in the RTA apparatus. The sizes 
of the via holes were same as in the example 2. 
The specimens mentioned above were subjected to heat treatment and 
observations in the same manner as in the example A1. The heat treating 
conditions were same as in the example A1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment as in the example A1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
After the heat treatment in the RTA apparatus, there were conducted 
observations of the electron diffraction pattern and the scanning 
.mu.-RHEED image. All the specimens showed spot electron beam diffraction 
patterns as shown in FIG. 14B, with an intensity higher than that before 
the heat treatment, regardless of the Si wafer surface orientation, 
SiO.sub.2 film thickness, via hole dimensions or second Al film thickness 
as in the example 1. The scanning .mu.-RHEED images obtained by utilizing 
the intensities of the diffraction spot A (111 diffracted spot) and spot C 
(202 diffracted spot) of the diffraction pattern in FIG. 14B were similar 
to those shown in FIGS. 15B and 15C, as in the example A1. The Al film 
deposited on the area of via hole pattern showed high intensities for both 
spots A and C, indicating transformation to monocrystalline state by heat 
treatment. 
As in the example A1, in the heat treatment at 650.degree. C., the Al film 
on SiO.sub.2 was transformed into monocrystalline state but showed 
unevenness in the thickness after the heat treatment. Also the 
measurements of element distribution in the direction of depth by electron 
spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy 
(AES), the specimen heat treated at 650.degree. C. showed diffusion of Al, 
Si and O at the interface between SiO.sub.2 and second Al film. Also 
transformation to monocrystalline state did not occur by the heat 
treatment at 500.degree. C. 
EXAMPLE A3 
Specimens were prepared with the line-and-space patterns as in the example 
3 and subjected to heat treatment in the RTA apparatus. 
The specimens were subjected to heat treatment and observations in the same 
manner as in the example A1. The heat treating conditions were same as 
those in the example A1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment as in the example A1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
After heat treatment in the RTA apparatus, there were conducted 
observations of the electron beam diffraction pattern and the scanning 
.mu.-RHEED image. All the specimens showed spot electron beam diffraction 
patterns as shown in FIG. 14B, with a higher intensity than before the 
heat treatment, regardless of the Si wafer surface orientation, SiO.sub.2 
film thickness, via hole dimensions or second Al film thickness as in the 
example A1. The scanning .mu.-RHEED images obtained by utilizing the 
intensities of the diffraction spot A (111 diffracted spot) and spot C 
(202 diffracted spot) of the diffraction pattern in FIG. 14B were similar 
to those shown in FIGS. 15B and 15C, as in the example A1 The Al film 
deposited on the area of line-and-space pattern showed high intensities 
for both spots A and C, indicating transformation to monocrystalline state 
by heat treatment. 
As in the example A1, in the heat treatment at 650.degree. C., the Al film 
on SiO.sub.2 was transformed into monocrystalline state but showed 
unevenness in the thickness after the heat treatment. Also the 
measurements of element distribution in the direction of depth by electron 
spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy 
(AES), of Al, Si and O at the interface between SiO.sub.2 and second Al 
film. Also transformation to monocrystalline state did not occur by the 
heat treatment at 500.degree. C. 
EXAMPLE A4 
Specimens with a cross-section as shown in FIG. 1A were prepared in the 
same manner as in the example 1 or A1, and were heat treated in the 
scanning .mu.-RHEED microscope. 
Said specimens were different from those of the example A1 in the pattern 
formed on the Si wafer. As shown in FIG. 16A, the SiO.sub.2 film is 
provided with apertures in an area I but is free from such apertures in an 
area II. The pattern in the area I was the checkered pattern, via hole 
pattern or line-and-space pattern shown in FIG. 2A, 2B or 2C. In the 
checkered pattern, the size L1 was varied in 6 levels of 0.25, 0.5, 1, 2, 
3 and 5 .mu.m. In the via hole pattern, L2 was varied in 5 levels of 0.25, 
0.5, 1, 2 and 5 .mu.m while L2 in 3 levels or 1, 2 and 5 .mu.m, and 15 
different patterns were prepared by the combinations of L2 and L3. In the 
line-and-space pattern, L3 was varied in 4 levels of 0.25, 0.5, 1 and 2 
.mu.m while L5 in 3 levels of 1, 2 and 5 .mu.m, and 12 different patterns 
were prepared by the combinations of L4 and L5. The thicknesses of the 
SiO.sub.2 film and of the Al film deposited on the entire surface (second 
Al film 4 in FIG. 1A) were same as those in the example A1. These 
specimens prepared as explained above were subjected to the heat treatment 
and the observations in the same manner as in the example A1. The heat 
treating conditions were same as those in the example A1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope prior to the heat treatment as in the example A1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
After the heat treatment in the RTA apparatus, there were conducted 
observations of the electron diffraction pattern and the scanning 
.mu.-RHEED image. All the specimens showed spot electron beam diffraction 
patterns as shown in FIG. 14B, with a higher intensity than before the 
heat treatment, regardless of the Si wafer surface orientation, SiO.sub.2 
film thickness, shape and dimension of the pattern formed in the area I, 
or second Al film thickness, as in the example A1. The scanning .mu.-RHEED 
images obtained by utilizing the intensities of the diffraction spot A 
(111 diffracted spot) and spot C (202 diffracted spot) of the diffraction 
pattern in FIG. 14B were similar to those shown in FIGS. 15B and 15C, as 
in the example A1, wherein hatched areas indicate areas with high 
intensity of diffracted spots, and a (111) monocrystalline state is 
present were the diffracted spots A and C are both strong. As shown in 
FIGS. 16B and 16C, it was found that the area transformed into 
monocrystalline state extended by about 10 .mu.m (corresponding to L6 in 
FIG. 16C) from the area I containing apertures. It was thus confirmed that 
the monocrystalline transformation by heat treatment extended by about 10 
.mu.m from the patterned area I even in the absence of the exposed silicon 
under the Al film. 
As in the example A1, in the heat treatment at 650.degree. C., the Al film 
on SiO.sub.2 was transformed into monocrystalline state but showed 
unevenness in the thickness after the heat treatment. Also the 
measurements of element distribution in the direction of depth by electron 
spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy 
(AES), the specimen heated treated at 650.degree. C. showed diffusion of 
Al, Si and O at the interface between SiO.sub.2 and second Al film. Also 
transformation to monocrystalline state did not occur by the heat 
treatment at 500.degree. C. 
EXAMPLE A5 
In the examples A1, A2, A3 and A4, the first insulation film was composed 
of SiO.sub.2 obtained by thermal oxidation. In the present example, 
similar specimens as in the foregoing examples were prepared employing, as 
the first insulation film, an SiO.sub.2 film obtained by normal pressure 
CVD (hereinafter represented as CVD SiO.sub.2 ), a boron-doped oxide film 
obtained by normal pressure CVD (BSG), a phosphor-doped oxide film 
obtained by normal pressure CVD (PSG), a boron-and phosphor-doped oxide 
film obtained by normal pressure CVD (BPSG), a nitride film obtained by 
plasma CVD (P-SiN), a thermal nitride film (T-SiN), a thermal nitride film 
obtained by low pressure CVD (LP-SiN), and a nitride film obtained by ECR 
apparatus (ECR-SiN). These specimens were subjected to observation of the 
X-ray diffraction pattern and the electron beam diffraction pattern by the 
conventional RHEED apparatus, then heat treat in the scanning .mu.-RHEED 
microscope, and observations of the electron beam diffraction pattern and 
of the scanning .mu.-RHEED image. The thickness of the first insulation 
films was selected as ca. 5000 .ANG., except that the thermal nitride film 
(T-SiN) was made with a thickness of ca. 100 .ANG.. The thickness of the 
second Al film was selected as ca. 7500 .ANG.. Formed patterns were same 
as those in the examples A1, A2, A3 and A4. 
There were obtained similar results to those in the examples A1, A2, A3 and 
A4. 
EXAMPLE A6 
In the examples A1, A2, A3, A4 and A5, the first and second Al films were 
both prepared by low pressure CVD. In the present example, the second Al 
film was prepared by sputtering, but other conditions were maintained same 
as in the examples A1, A2, A3, A4 and A5. 
There were obtained similar results to those in the examples A1, A2, A3, A4 
and A5. 
EXAMPLE A7 
In the examples A1, A2, A3, A4, A5 and A6, the first and second Al films 
were both composed of pure aluminum. In the present example, pure aluminum 
was replaced by Al-Si, with Si content varied as 0.2, 0.5 or 1.0%. 
There were obtained similar results to those in the examples A1, A2, A3, 
A4, A5 and A6. 
EXAMPLE A8 
In the examples A1-A7, the specimens had the cross-sectional structure as 
shown in FIG. 1A. After the deposition of the first and second Al as in 
the examples A1-A7, the specimens were subjected to the formation of a 
second insulation film 5 as shown in FIG. 1B, and to heat treatment in the 
RTA apparatus. Conditions were maintained same as in the examples A1-A7, 
except for the cross-sectional structure. The crystallinity of the second 
Al film after the heat treatment was observed, after the removal of the 
second insulation film 5, by the conventional RHEED apparatus and the 
scanning .mu.-RHEED microscope. 
The insulation film 5 in FIG. 1B was composed of SiO.sub.2, PSG, BSG or 
BPSG obtained by normal pressure CVD, silicon nitride film obtained by 
plasma CVD, or silicon nitride film obtained by ECR apparatus. The film 
thickness was varied in 3 levels of 1000, 3000 and 5000 .ANG. in each of 
said films. 
There were obtained similar results to those in the examples A1-A7. 
EXAMPLE B1 
There were employed specimens same as those in the example 1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED IMAGE BY THE SCANNING .mu.-RHEED 
microscope prior to the heat treatment as in the example 1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
The above-mentioned specimens were subjected to laser heating in the 
following manner. There was employed a continuously oscillated Ar laser 
(wavelength ca. 488 and 514.5 nm; maximum oscillation output: 20 W), with 
a beam diameter on the specimen of ca. 20, 30, 70 or 100 .mu.m. There were 
conducted scanning motions repeated in one direction, as shown in FIG. 5A. 
The pitch of the scanning motions was selected approximately equal to the 
beam diameter. The scanning speed of the laser beam was ca. 0.5, 1, 2, 5 
or 10 cm/min. The substrate surface temperature, measured with a radiation 
thermometer employed a PbS probe, was selected as ca. 450.degree., 
550.degree., 600.degree., 650.degree. or 700.degree. C. 
The substrate surface temperature was dependent on the laser beam diameter, 
laser output and laser beam scanning speed. In the following experiments, 
for each given set of laser beam diameter, laser beam scanning speed and 
scanning pitch, the laser output was so regulated as to obtain the surface 
temperature of ca. 450.degree., 550.degree., 600.degree., 650.degree. or 
700.degree. C. 
The laser heating was conducted in hydrogen gas of atmospheric pressure. 
After the heat treatment in the above-mentioned laser heating conditions, 
there were conducted observations of the electron beam diffraction pattern 
and-the scanning .mu.-RHEED image in the scanning .mu.-RHEED microscope. 
All the specimens showed spot electron beam diffraction patterns as shown 
in FIG. 14B, with a higher intensity than before heating, if the surface 
temperature is at least equal to 550.degree. C., regardless of the Si 
wafer surface orientation, SiO.sub.2 film thickness, checkered pattern 
size or second Al film thickness and also regardless of the laser beam 
diameter, scanning speed or scanning pitch. The diffraction pattern in 
FIG. 14B was identified, from the spot position, as generated by the 
electron beam introduced from a direction [101] into the Al(111) plane. 
The scanning .mu.-RHEED images obtained by utilizing the intensities of 
the diffraction spot A (111 diffracted spot) and spot C (202 diffracted 
spot) of the diffraction pattern in FIG. 14B were similar to those shown 
in FIGS. 15B and 15C, wherein hatched areas indicate areas with high 
intensity of diffracted spots. The Al film deposited on the 
checker-patterned area showed high intensities for both spots A and C, 
indicating transformation to monocrystalline state by the heat treatment. 
Also in the observation of the heat treated specimen by the electron beam 
diffraction pattern by the conventional RHEED apparatus, all the specimens 
showed spot pattern indicating monocrystalline state, as shown in FIG. 
14B. 
In this manner, aluminum which had been in polycrystalline state when 
deposited was transformed into monocrystalline state by laser heating. In 
the measurements of element distribution in the direction of depth by 
Auger electron spectroscopy and secondary ion mass spectroscopy, the 
specimens treated at 650.degree. C. or higher showed diffusion Si and Al 
at the interface between the insulation film on the substrate surface and 
the second Al film. 
EXAMPLE B2 
Specimens with checkered patterns were prepared in the same manner as in 
the example 2. The thicknesses of the SiO.sub.2 film and of the Al film 
deposited on the entire wafer surface (second Al film 4 in FIG. 1) were 
same as those in example 1. Thus prepared specimens were subjected to the 
heat treatment and the observations in the same manner as in the example 
B1. The heat treating conditions were same as in the example B1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope, prior to the heat treatment as in the example B1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
Then heat treatment with laser beam irradiation was conducted in the same 
conditions as in the example B1, and there were conducted observations of 
the electron beam diffraction pattern and the scanning .mu.-RHEED image. 
As in the example B1, all the specimens treated at a surface temperature 
of 550.degree. C. or higher were confirmed to be transformed into 
monocrystalline state, regardless of the Si wafer surface orientation, 
SiO.sub.2 film thickness, checkered pattern size or second Al film 
thickness and also regardless of the laser beam diameter, scanning speed 
or scanning pitch. In the measurement of element distribution in the 
direction of depth by Auger electron spectroscopy or secondary ion mass 
spectroscopy, the specimens treated at a surface temperature of 
650.degree. C. or higher showed diffusion of Si and Al at the interface of 
the insulation film on the substrate surface and the second Al film, as in 
the example 1. 
EXAMPLE B3 
Specimens with a cross section as shown in FIG. 1A were prepared in the 
same manner as in the example B1 and were subjected to laser heating. 
Different from the example B1, said specimens were given line-and-space 
patterns shown in FIG. 2C, with dimensions L4 and L5 same as in the 
example 3. 
Thus prepared specimens were subjected to the heat treatment and the 
observations in the same manner as in the example B1. The heat treating 
conditions were also same as in the example B1. 
Based on the results of X-ray diffraction, electron beam diffraction 
pattern by the conventional RHEED apparatus, and electron beam diffraction 
pattern and scanning .mu.-RHEED image by the scanning .mu.-RHEED 
microscope, prior to the heat treatment as in the example B1, the Al 
deposited on the entire surface (second Al) in all the specimens was 
identified as polycrystals with an orientation (111), consisting of 
crystal grains of several to ten microns. 
Then heat treatment with laser beam irradiation was conducted in the same 
conditions as in the example B1, and there were conducted observations of 
the electron beam diffraction pattern and the scanning .mu.-RHEED image in 
the scanning .mu.-RHEED microscope. As in the example B1, all the 
speciments treated at a surface temperature of 550.degree. C. or higher 
were confirmed to be transformed into monocrystalline state, regardless of 
the Si wafer surface orientation, SiO.sub.2 film thickness, line-and-space 
pattern dimensions or second Al film thickness and also regardless of the 
laser beam diameter, scanning speed of scanning pitch. In the measurement 
of element distribution in the direction of depth by Auger electron 
spectroscopy or secondary ion mass spectroscopy, the specimens treated at 
a surface temperature of 650.degree. C. or higher showed diffusion of Si 
and Al at the interface between the insulation film on the substrate 
surface and the second Al film, as in the example B1. 
EXAMPLE B4 
Specimens were prepared in the same manner as in the examples B1, B2 and 
B3. The present example is different from said examples in the shape of 
the laser beam and the scanning method thereof. 
The above-mentioned specimens were subjected to heating by a laser, which 
was a continuously oscillated Ar laser (wavelength ca. 488 and 514.5 nm). 
The beam on the specimen was a flat parallel beam as shown in FIG. 6A. A 
circular beam 67 was transformed into a parallel beam 71 by an optical 
system 70 employing a cylindrical lens. The shape of the parallel beam was 
ca. 20 .mu.m.times.1 cm, 50 .mu.m.times.1 cm or 100 .mu.m.times.1 cm. The 
scanning was conducted in one direction as shown in FIG. 6A, with a speed 
of ca. 0.5, 1, 2, 5 or 10 cm/min. The substrate surface temperature, 
measured by a radiation thermometer employing a PbS probe, was selected at 
ca. 450.degree., 550.degree., 600.degree., 650.degree. or 700.degree. C. 
The substrate surface temperature was dependent on the shape, output and 
scanning speed of the laser beam. In the following experiments, for each 
given set of diameter and scanning speed of the laser beam, the laser 
output was so regulated as to obtain the surface temperature of ca. 
450.degree., 550.degree., 600.degree., 650.degree. or 700.degree. C. 
mentioned above. The laser heating was conducted in hydrogen gas of 
atmospheric pressure. 
After the heating with the laser beam, the results of observations with the 
scanning .mu.-RHEED microscope, X-ray diffraction and convention RHEED 
apparatus indicated that the second Al was transformed into 
monocrystalline state, as in the examples B1, B2 and B3, when the 
substrate surface temperature was ca. 550.degree. C. or higher. 
Also as in the examples B1, B2 and B3, the measurement of element 
distribution in the direction of depth by Auger electron spectroscopy or 
secondary ion mass spectroscopy showed the diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 650.degree. C. 
or higher. 
EXAMPLE B5 
In the examples B1, B2 and B3, the second Al film was formed on the entire 
surface of the specimen as shown in cross section in FIG. 1A. In the 
present example, an insulation film 5 was formed on the specimens of the 
examples B1, B2 and B3, as shown in FIG. 1B, and the heat treatment with 
laser was conducted in the same manner as in said foregoing examples. The 
insulation film on the second Al film was composed of a SiO.sub.2 film 
obtained by normal pressure CVD (hereinafter expressed as CVD SiO.sub.2 ), 
a boron-doped oxide film obtained by normal pressure CVD (BSG), a 
phosphor-doped oxide film obtained by normal pressure CVD (PSG), a boron- 
and phosphor-doped oxide film obtained by normal pressure CVD (BPSG), a 
nitride film obtained by plasma CVD (P-SiN), or a nitride film obtained by 
CER apparatus (ECR-SiN). The insulation film on the second Al film will 
hereinafter be called the second insulation film. The thickness of said 
second insulation film was selected as 1000, 2000, 5000 or 10000 .ANG.. 
The laser heating conditions were same as in the examples B1, B2 and B3. 
After the heating with laser beam, the specimens were subjected to the 
removal of the second insulation film by etching and then subjected to the 
observations of the electron beam diffraction pattern and the scanning 
.mu.-RHEED image in the scanning .mu.-RHEED microscope, as in the examples 
B1, B2 and B3. As in said examples, the obtained results indicated that 
the second Al was transformed into monocrystalline state when the 
substrate temperature was 550.degree. C. or higher. Also as in the 
examples B1, B2 and B3, the measurement of element distribution in the 
direction of depth by Auger electron spectroscopy or secondary ion mass 
spectroscopy indicated diffusion of Si and Al at the interface between the 
insulation film on the substrate surface and the second Al film when the 
substrate surface temperature was equal to 650.degree. C. or higher 
EXAMPLE B6 
In the example B4, the second Al film was formed on the entire surface of 
the specimen as shown in cross section in FIG. 1A. In the present example, 
a second Al film was formed on the specimens of the example B4 as shown in 
FIG. 1B, and the laser heating was conducted in the same manner as in said 
example B4. The insulation film on the second Al film was composed of CVD 
SiO.sub.2, BSG, PSG, BPS, P-SiN or ECR-SiN. Said insulation film on the 
second Al film will hereinafter be called a second insulation film. The 
thickness of said second insulation film was selected as 1000, 2000, 5000 
or 10000 .ANG.. The laser heating conditions were same as those in the 
example B4. After the heating with the laser beam, the specimens were 
subjected to the removal of the second insulation film by etching, and to 
the observations of the electron beam diffraction pattern and the scanning 
.mu.-RHEED image by the scanning .mu.-RHEED microscope as in the example 
B4. The obtained results indicated, as in the example B 4, that the second 
Al film was transformed into monocrystalline state when the substrate 
temperature was 550.degree. C. or higher. Also the measurement of element 
distribution in the direction of depth by Auger electron spectroscopy or 
secondary ion mass spectroscopy indicated the diffusion of Si and Al at 
the interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 650.degree. C. 
or higher, as in the example B4. 
EXAMPLE B7 
In the examples B1, B2, B3 and B4, the insulation film formed on the Si 
substrate as shown in FIG. 1A was composed of SiO.sub.2, formed by thermal 
oxidation. In the present example, the insulation film on the Si substrate 
was composed of CVD SiO.sub.2, BSG, PSG, BPSG, P-SiN, T-SiN, LP-SiN or 
ECR-SiN, with thicknesses of 5 levels of 1000, 2500, 5000, 7500 and 10000 
.ANG.. 
The thicknesses of the first and second Al films, and the laser heating 
conditions were same as those in the examples B1, B2, B3 and B4. 
As in the examples B1, B2 B3 and B4, the second Al was transformed to 
monocrystalline state when the substrate temperature was 550.degree. C. or 
higher. Also as in said examples, the measurement of element distribution 
in the direction of depth by Auger electron spectroscopy or secondary ion 
mass spectroscopy indicated diffusion of Si and Al at the interface 
between the insulation film on the substrate surface and the second Al 
film, when the substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE B8 
In the example B7, the second Al film was formed over the entire surface of 
the specimen, as shown in cross section in FIG. 1A. In the present 
example, an insulation film was formed on the second Al film of the 
specimens of the example B7, as shown in FIG. 1B, and the heat treatment 
with the laser beam was conducted in the same manner as in the example B7. 
The insulation film on the second Al was composed of CVD-SiO.sub.2, BSG, 
PSG, BPSG, P-SiN, T-SiN, LP-SiN or ECR-SiN, with a thickness varied in 5 
levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. 
The thicknesses of the first and second Al films and the laser heating 
conditions were same as in the examples B1, B2, B3 and B4. As in the 
example B7, the second Al was transformed into monocrystalline state when 
the substrate temperature was 550.degree. C. or higher. Also as in the 
example B7, the measurement of element distribution in the direction of 
depth by Auger electron spectroscopy or secondary ion mass spectroscopy 
indicated diffusion of Si and Al at the interface between the insulation 
film on the substrate surface and the second Al film, when the substrate 
surface temperature was 650.degree. C. or higher. 
EXAMPLE B9 
There was measured the area of monocrystalline transformation of the second 
Al by laser heating. The specimen had a structure schematically shown in 
FIG. 5A and a cross section shown in FIG. 1A. The insulation film on the 
Si substrate was provided with a line of a width L10, which was varied in 
6 levels of 0.5, 1, 2, 5, 10 and 20 .mu.m. The surface orientation of the 
Si substrate was selected as (100) or (111). The insulation film was 
composed of SiO.sub.2 obtained by thermal oxidation, with a thickness 
varied in 5 levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. Al deposited 
over the entire surface (second Al 4 in FIG. 1A or second Al 63 in FIG. 
5A) had a thickness of 5 levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. 
By taking combinations of the above-mentioned 4 conditions, namely the Si 
substrate surface orientation, SiO.sub.2 film thickness, width L10 of the 
first Al and second Al film thickness, there were prepared 
2.times.5.times.8.times.6=480 specimens. 
Based on X-ray diffraction, electron beam diffraction pattern obtained by 
the conventional RHEED apparatus, and electron beam diffraction pattern 
and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope, the second Al was identified as polycrystals consisting of 
crystal grains of several to ten microns, as in the example 1. 
For heating there was employed a continuously oscillated Ar laser 
(wavelength ca. 488 and 514.5 nm, maximum oscillation output: 20 W). The 
beam diameter on the specimen was ca. 20, 30, 70 or 100 .mu.m, and the 
scanning was conducted in one direction in repeated manner as shown in 
FIG. 5A. The pitch of scanning was selected approximately same as the beam 
diameter. The scanning speed of the laser beam was ca. 0.5, 1, 2, 5 or 10 
cm/min. The substrate surface temperature, measured by a radiation 
thermometer employing a PbS probe, was selected as ca. 450.degree., 
550.degree., 600.degree., 650.degree. or 700.degree. C. The substrate 
surface temperature was dependent on the diameter, output and scanning 
speed of the laser beam In the following experiments, for each given set 
of diameter, scanning speed and scanning pitch of the laser beam, the 
laser output was so regulated as to obtain the above-mentioned surface 
temperature of ca. 450.degree., 550.degree., 600.degree., 650.degree. or 
700.degree. C. The laser heating was conducted in hydrogen gas of 
atmospheric pressure. 
After the heating with laser, the electron diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The electron diffraction pattern showed spots with a higher 
intensity than before the heat treatment, as in the example B1 (FIG. 14B). 
The scanning .mu.-RHEED images obtained utilizing the 111 and 202 
diffracted spots were similar to those shown in FIGS. 17B and 17C. The 
direction of the first Al is parallel to y-direction in FIG. 17A, and the 
scanning direction of the laser beam is parallel to x-direction. The 
length of area transformed into monocrystalline state can be determined by 
measuring L8 in FIG. 17C. Though L8 is illustrated as about 10-20 .mu.m in 
FIG. 17C, it was in fact about 1 cm when the substrate temperature was 
550.degree. C. or higher. Stated differently, the second Al film on 
SiO.sub.2 was transformed into monocrystalline state over a length of 1 
cm, utilizing monocrystalline first Al as the seed. As in the examples B1, 
B2, B3 and B4, the measurement of element distribution in the direction of 
depth by Auger electron spectroscopy or secondary ion mass spectroscopy 
indicated diffusion of Si and Al at the interface between the insulation 
film on the substrate surface and the second Al film, when the substrate 
surface temperature was 650.degree. C. or higher. 
EXAMPLE B10 
Specimens were prepared in the same manner as in the example B9, and were 
subjected to heat treatment by laser. 
The specimens were different in the cross-sectional structure from those of 
the example B9. In the specimens of the example B9, the second Al film was 
formed on the entire surface of the specimen as shown in FIG. 1A or 5A. In 
this example, an insulation film was formed on the second Al as shown in 
FIG. 1B or 5B, and the heat treatment with the laser beam was conducted in 
the same manner as in the example B9. The insulation film, hereinafter 
called the second insulation film, on the second Al was composed of 
CVD-SiO.sub.2, PSG, BSG, BPSG, P-SiN or ECR-SiN. The thickness of the 
second insulation film was selected as 1000, 2000, 5000 or 10000 .ANG.. 
The laser heating conditions were same as in the examples B1, B2 and B3. 
After the laser heating, the second insulation film was removed by 
etching, and the electron beam diffraction pattern and the scanning 
.mu.-RHEED image were observed in the scanning .mu.-RHEED microscope. The 
obtained results indicated, as in the example B9, that the second Al was 
transformed into monocrystalline state when the substrate temperature was 
550.degree. C. or higher. Observation of the area transformed into 
monocrystalline state by the scanning .mu.-RHEED image as in the example 
B9 provided similar results to those shown in FIGS. 17B and 17C, with L8 
of ca. 1 cm. Also as in the example B9, the measurement of element 
distribution in the direction of depth by Auger electron spectroscopy or 
secondary ion mass spectroscopy indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 650.degree. C. 
or higher. 
EXAMPLE B11 
There was measured the area of monocrystalline transformation of the second 
Al by laser heating. The specimens had a structure schematically shown in 
FIG. 6A and a cross section shown in FIG. 1B. The insulation film on the 
Si substrate was provided with a line of a width L10, and the dimensions 
of the specimens were same as in the example B9. Based on X-ray 
diffraction, electron beam diffraction pattern obtained by the 
conventional RHEED apparatus, and electron beam diffraction pattern and 
scaning .mu.-RHEED image obtained by the scanning .mu.-RHEED microscope, 
the second Al was identified as polycrystals consisting of crystal grains 
of several to ten microns, as in the example B9. 
The above-mentioned specimens were subjected to heating by a laser, which 
was a continuously oscillated Ar laser (wavelength ca. 488 and 514.5 nm). 
The beam on the specimen was a flat parallel beam as shown in FIG. 6A. A 
circular beam was converted into a parallel beam by an optical system 70 
employing a cylindrical lens. The shape of said parallel beam was ca. 20 
.mu.m.times.1 cm, 50 .mu.m.times.1 cm or 100 .mu.m.times.1 cm. The 
scanning was conducted in one direction as shown in FIG. 6A, with a speed 
of ca. 0.5, 1, 2, 5 or 10 cm/min. The substrate surface temperature, 
measured by a radiation thermometer employing a PbS probe, was selected at 
ca. 450.degree., 550.degree., 600.degree., 650.degree. or 700.degree. C. 
The substrate surface temperature was dependent on the shape, output and 
scanning speed of the laser beam. In the following experiments, for each 
given set of diameter and scanning speed of the laser beam, the laser 
output was so regulated as to obtain the above-mentioned surface 
temperature of ca. 450.degree., 550.degree., 600.degree., 650.degree. or 
700.degree. C. The laser heating was conducted in hydrogen gas of 
atmospheric pressure. 
After the heating with laser, the electron diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The electron diffraction pattern showed spots with a higher 
intensity than before the heat treatment as in the example B9 (FIG. 14B). 
The scanning .mu.-RHEED images obtained utilizing the 111 and 202 
diffracted spots were similar to those shown in FIGS. 17B and 17C. The 
direction of the first Al was parallel to y-direction in FIG. 17A, and the 
scanning direction of the laser beam was parallel to x-direction. The 
length of area transformed to monocrystalline state can be determined by 
measuring L8 in FIG. 17C. Though L8 is illustrated as about 10-20 .mu.m in 
FIG. 17C, it was in fact about 1 cm when the substrate temperature was 
550.degree. C. or higher. Stated differently, the second Al film on 
SiO.sub.2 was transformed into monocrystalline state over a length of 1 
cm, utilizing monocrystalline first Al as the seed. As in the examples B1, 
B2, B3 and B4, the measurement of element distribution in the direction of 
depth by Auger electron spectroscopy or secondary ion mass spectroscopy 
indicated diffusion of Si and Al at the interface between the insulation 
film on the substrate surface and the second Al film, when the substrate 
surface temperature was 650.degree. C. or higher. 
EXAMPLE B12 
Specimens were prepared in the same manner as in the example B11, and were 
subjected to heat treatment by laser. The specimens were different in the 
cross-sectional structure from those of the example B11. In the specimens 
of the example B11, the second Al film was formed on the entire surface of 
the specimen as shown in FIG. 1A or 5A. In this example, an insulation 
film was formed on the second Al as shown in FIG. 1B or 5B, and the heat 
treatment with the laser beam was conducted in the same manner as in the 
example B11. The insulation film, hereinafter called the second insulation 
film, on the second Al was composed of CVD-SiO.sub.2, PSG, BSG, BPSG, 
P-SiN or ECR-SiN. The thickness of the second insulation film was selected 
as 1000, 2000, 5000 or 10000 .ANG.. After the laser heating, the second 
insulation film was removed by etching, and the electron beam diffraction 
pattern and the scanning .mu.-RHEED image were observed in the scanning 
.mu.-RHEED microscope as in the example B11. The obtained results 
indicated, as in the example B11, that the second Al was transformed into 
monocrystalline state when the substrate temperature was 550.degree. C. or 
higher. Observation of the area transformed into monocrystalline state by 
the scanning .mu.-RHEED image as in the example B11 provided similar 
results to those shown in FIGS. 17B and 17C, with L8 of ca. 1 cm. Also as 
in the example B11, the measurement of element distribution in the 
direction of depth by Auger electron spectroscopy or secondary ion mass 
spectroscopy indicated diffusion of Si and Al at the interface between the 
insulation film on the substrate surface and the second Al film, when the 
substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE B13 
Laser heating was conducted in the same method and procedure as in the 
examples B9 and B10 with specimens which are however different in shape 
from those in said examples The structure of the specimens is shown in 
FIG. 7A. The insulation film on the second Al (second insulation film) was 
formed uniformly on the specimen in the example B10, but, in the present 
example, it was formed in stripes substantially perpendicular to the 
direction of the first Al (line direction) as shown in FIG. 7A. The second 
insulation film was composed of CVD-SiO.sub.2, PSG, BSG, BPSG, P-SiN or 
ECR-SiN, with a thickness of 1000, 2000, 5000 or 10000 .ANG.. The stripes 
of the second insulation film were formed in 16 different dimensions, by 
taking combinations of L14 as 1, 2, 5 and 10 .mu.m and L15 as 1, 2, 5 and 
10 .mu.m. The laser heating conditions were same as those in the examples 
B1, B2 and B3. After the laser heating, the second insulation film was 
removed by etching, and the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed by the scanning .mu.-RHEED 
microscope, as in the example B9. 
The obtained results indicated, as in the example B9, that the second Al 
was transformed into monocrystalline state when the substrate temperature 
was 550.degree. C. or higher. The scanning .mu.-RHEED images observed in 
the area of monocrystalline transformation as in the example B9 were 
similar to those shown in FIGS. 17B and 17C, with L8 being about 1 cm. 
Also as in the example B9, the measurement of element distribution in the 
direction of depth by Auger electron spectroscopy or secondary ion mass 
spectroscopy indicated diffusion of Si and Al at the interface between the 
insulation film on the substrate surface and the second Al film, when the 
substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE B14 
Specimens were prepared in the same manner as in the example B13 and 
subjected to heat treatment by laser. This example is however different in 
the laser beam scanning method from said example B13. There was employed a 
continuously oscillated Ar laser (wavelength: ca. 488.5 and 415.5 nm) with 
a parallel flat beam on the specimen surface, as shown in FIG. 7B. A 
circular beam was converted into a parallel beam by an optical system 70 
employing a cylindircal lens. The dimension of said parallel beam was ca. 
20 .mu.m.times.1 cm, 50 .mu.m.times.1 cm or 100 .mu.m.times.1 cm, and the 
scanning was conducted in one direction as shown in FIG. 7B. 
The scanning speed was ca. 0.5, 1, 2, 5 or 10 cm/min. The substrate surface 
temperature, measured with a radiation thermometer employing a PbS probe, 
was ca. 450.degree., 550.degree., 600.degree., 650.degree. or 700.degree. 
C. The substrate surface temperature was dependent on the shape, output 
and scanning speed of the laser beam. In the following experiments, for 
each given set of the diameter and the scanning speed of the laser beam, 
the laser output was so regulated as to obtain the above-mentioned surface 
temperature of ca. 450.degree., 550.degree., 600.degree., 650.degree. or 
700.degree. C. The laser heating was conducted in hydrogen gas of 
atmospheric pressure. 
As in the example B13, the obtained results indicated that the second Al 
was transformed into monocrystalline state when the substrate temperature 
was 550.degree. C. or higher. The scanning .mu.-RHEED images observed in 
the monocrystalline area as in the example B13 were similar to those shown 
in FIGS. 17B and 17C, with L8 being ca. 1 cm. Also as in the example B13, 
the measurement of element distribution in the direction of depth by Auger 
electron spectroscopy or secondary ion mass spectroscopy indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 650.degree. C. or higher. 
EXAMPLE B15 
In the examples B9, B10, B11, B12, B13 and B14, the insulation film formed 
on the Si substrate as shown FIGS. 5A, 5B, 6A, 6B, 7A or 7B was composed 
of SiO.sub.2 obtained by thermal oxidation. In the present example, the 
insulation film on the Si substrate was CVD-SiO.sub.2, BSG, PSG, BPSG, 
P-SiN, T-SiN, LP-SiN or ECR-SiN, with a thickness of 1000, 2000, 5000, 
7500 or 10000 .ANG.. The thicknesses of the first and second Al films were 
same as those in the examples B1, B2, B3 and B4. 
As in the examples B9, B10, B11, B12, B13 and B14, the monocrystalline 
transformation of the second Al film occurred when the substrate 
temperature was 550.degree. C. or higher. Also as in the examples B9, B10, 
B11, B12, B13 and B14, the measurement of element distribution in the 
direction of depth by Auger electron spectroscopy or secondary ion mass 
spectroscopy indicated diffusion of Si and Al at the interface between the 
insulation film on the substrate surface and the second Al film, when the 
substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE B16 
In the examples B1-B15, the first and second Al films were composed of pure 
aluminum obtained by the LP-CVD method utilizing DMAH (dimethylaluminum 
hydride) and hydrogen. In this example, pure aluminum was replaced by 
Al-Si, deposited by the addition of Si.sub.2 H.sub.6 in the LP-CVD method 
utilizing DMAH and hydrogen. The Si content in the first and second Al-Si 
films was varied as 0.2, 0.5 or 1.0%. 
The heat treatment was conducted in the same manner as in the examples 
B1-B15, with mere replacement Al by Al-Si. The obtained results were 
similar to those obtained in said examples B1-B15. 
EXAMPLE B17 
In the examples B1-B15, the first and second Al films were both formed by 
the LP-CVD method employing DMAH and hydrogen. In order to transform the 
second Al film by heat treatment into monocrystalline state, the first Al 
film has to be monocrystalline. Said LP-CVD method has the advantage of 
being capable of depositing the first and second Al films in succession in 
a same apparatus, but the second Al film need not be formed by a CVD 
method as long as it is polycrystalline or amorphous. 
The present example was conducted in the same manner as the examples 
B1-B15, except that the second Al film alone was formed by sputtering. 
Based on the X-ray diffraction, electron beam diffraction pattern obtained 
by the conventional RHEED apparatus, and electron beam diffraction pattern 
and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope, the second Al film in deposited state was identified as 
polycrystalline, consisting of crystal grains of about 1 .mu.m or less. 
By the heat treatment in same conditions in the examples B1-B15, there were 
obtained results, as in the examples B1-B15, that the second Al was 
transformed into monocrystalline state when the substrate temperature was 
550.degree. C. or higher. However the transformed monocrystalline area L8, 
measured as in the examples B9-B14, was about 0.8 cm, smaller than 1 cm 
obtained when the CVD method was employed for the second Al film. Also as 
in the examples B1-B15, the measurement of element distribution in the 
direction of depth, by Auger electron spectroscopy or secondary ion mass 
spectroscopy, indicated diffusion of Si and Al at the interface between 
the insulation film on the substrate surface and the second Al film when 
the substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE B18 
In this example, the specimen structure and the heating conditions were 
same as in the examples B1-B15, but the first Al was composed of Al-Si 
formed by LP-CVD method employing DMAH, hydrogen and Si.sub.2 H.sub.6, 
while the second Al was composed of pure aluminum formed by LP-CVD 
utilizing DMAH and hydrogen. 
The Si content in the first Al-Si film was selected as 0.2, 0.5 or 1.0%. 
There were obtained results similar to those in examples B1-B15. 
EXAMPLE B19 
In this example, the specimen structure and the heating conditions were 
same as in the examples B1-B15, but the first Al was composed of Al-Si 
formed by LP-CVD employing DMAH, hydrogen and Si.sub.2 H.sub.6 while the 
second Al was composed of Al-Si formed by sputtering. The Si content in 
the first Al-Si film was selected as 0.2, 0.5 or 1.0%. 
There were obtained similar results to those in the examples B1-B15. 
However the transformed monocrystalline area L8, measured as in the 
examples B9-B14, was ca. 0.8 cm, which was shorter than 1 cm obtained when 
the second Al was formed by CVD. 
EXAMPLE B20 
In the examples B1-B19, the heating was conducted by laser beam irradiation 
from the top surface of specimen. In this example, heating was conducted 
by heating from the bottom side of the specimen, in addition to the laser 
beam irradiation from the top surface. The bottom side heating was 
achieved by resistance heating of a specimen support (not shown). The 
temperature of the bottom surface of the specimen was selected as ca. 250, 
300 or 350.degree. C. The laser irradiating conditions were same as in the 
examples B1-B19. 
There were obtained results similar to those in the examples B1-B19. 
Transformation to monocrystalline state in the examples B1-B19 occurred at 
550.degree. C., but in the present example at a substrate surface 
temperature of ca. 500.degree. C. This is presumably because the flow of 
Al atoms in the second Al or Al-Si film at the surface was facilitated by 
a smaller irradiation energy due to the heating of specimen from the 
bottom side thereof. 
EXAMPLE C1 
Specimens with first and second Al films were prepared as explained in the 
examples 1, 2 and 3, and were heat treated with a linear heater. The first 
insulation film was patterned in the checkered pattern, via hole pattern 
and line-and-space pattern shown in FIGS. 2A, 2B and 2C, with dimensions 
L1-L5 same as in the examples B1-B3. Also the surface orientation of the 
Si substrate and the thicknesses of the first insulation film and the 
second Al film were same as in the examples B1-B3. 
In X-ray diffraction after the deposition of the first and second Al films, 
all the specimens showed an Al(111) peak only, regardless of the SiO.sub.2 
film thickness, pattern size or second Al film thickness. Also in the 
electron beam diffraction pattern observed in the conventional RHEED 
apparatus with an electron beam diameter of 100 .mu.m-1 mm.phi., all the 
specimens showed ring patterns as shown in FIG. 14A. Thus the Al deposited 
over the entire surface was confirmed as polycrystals with an orientation 
(111). Also in the observation of the electron beam diffraction pattern 
with an electron beam reduced to 0.1 .mu.m in the scanning .mu.-RHEED 
microscope, there were obtained spot patterns as shown in FIG. 14B, though 
the intensity was weak. Also the scanning .mu.-RHEED image utilizing the 
intensity of diffraction spots in the diffraction pattern indicated 
polycrystalline state consisting of crystal grains of several to ten 
microns, as shown in FIG. 15A. 
The above-mentioned specimens were heat treated with a linear heater in the 
following manner. 
FIG. 8 illustrates the heating method with the linear heater. The substrate 
82 is placed on a heating support 81 made of carbon. Above said substrate 
82 there is provided a linear heater 83 which is also of carbon and is 
energized by a power source 84. The heating support 81 is also heated by a 
heater (not shown) provided on the bottom side thereof. The linear heater 
83 moves in a direction 85. The heating was conducted in hydrogen gas of 
atmospheric pressure. 
The linear heater 83 was moved in the direction 85, with a speed of ca. 
0.5, 1, 2, 5 or 10 cm/min. The substrate surface temperature directly 
below the linear heater 83, measured with a radiation thermometer 
employing a PbS probe, was ca. 450.degree., 500.degree., 600.degree., 
650.degree. or 700.degree. C. 
After the heat treatment under the above-mentioned heating conditions, the 
electron beam diffraction pattern and the scanning .mu.-RHEED image were 
observed in the scanning .mu.-RHEED microscope. All the specimens showed 
spot patterns as shown in FIG. 14B, with a higher intensity than before 
the heating, regardless of the Si wafer surface orientation, SiO.sub.2 
film (first insulation film) thickness, shape and size of the pattern, or 
second Al film thickness, as long as the substrate surface temperature 
directly below the linear heater 83 was 550.degree. C. or higher. The 
diffraction pattern in FIG. 14B was identified, from the position of the 
spots, as being generated by the electron beam introduced from a direction 
[101] into the Al (111) plane. The scanning .mu.-RHEED images obtained 
utilizing the intensities of a diffraction spot A (111 diffracted spot) 
and a spot C (202 diffracted spot) in the pattern shown in FIG. 14B were 
similar to those shown in FIG. 15B and 15C, wherein areas of diffraction 
spots with high intensity are hatched. The Al film deposited on the 
checkered pattern, via hole pattern or line-and-space pattern (second Al 
film) provided high intensities both in the spots A and C, indicating the 
transformation to monocrystalline state by the heat treatment. Also in the 
electron beam diffraction pattern observed in-the conventional RHEED 
apparatus after the heat treatment, all the specimens provided spot 
patterns indicating monocrystalline state as shown in FIG. 14B. 
Thus the polycrystalline Al when deposited was transformed into 
monocrystalline state by heating. Measurement of element distribution in 
the direction of depth, by Auger electron spectroscopy (AES), indicated 
diffusion of Al, Si and O at the interface between SiO.sub.2 and the 
second Al. The transformation to monocrystalline state did not occur by 
heat treatment of 500.degree. C., 6 hrs. 
EXAMPLE C2 
In the example C1, the second Al film was formed on the entire surface of 
the specimen, as shown in cross section in FIG. 1A. In this example, an 
insulation film was formed on the second Al film at shown in FIG. 1B, and 
the heat treatment with the linear heater was conducted in the same manner 
as in the example C1. The insulation film on the second Al, to be 
hereinafter called the second insulation film, was composed of a SiO.sub.2 
film obtained by normal pressure CVD (hereinafter represented as 
CVD-SiO.sub.2), a boron-doped oxide film obtained by normal pressure CVD 
(BSG), a phosphor-doped oxide film obtained by normal pressure CVD (PSG), 
a boron- and phosphor-doped oxide film obtained by normal pressure CVD 
(BPSG), a nitride film obtained by plasma CVD (P-SiN), or a thermal 
nitride film obtained by the ECR apparatus (ECR-SiN), with a thickness of 
1000, 2000, 5000 or 10000 .ANG.. The heating conditions were same as in 
the example C1. After the heat treatment, the second insulation film was 
removed by etching, and the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope as in the example C1. The obtained results indicated, as in the 
example C1, that the second Al was transformed into monocrystalline state 
when the substrate temperature was 550.degree. C. or higher. Also as in 
the example C1, the measurement of element distribution in the direction 
of depth, by Auger electron spectroscopy or secondary ion mass 
spectroscopy, indicated the diffusion of Si and Al at the interface 
between the insulation film on the substrate surface and the second Al 
film, when the substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE C3 
In the example C1, the first insulation film formed on the Si substrate, 
shown in FIG. 1A, was composed of SiO.sub.2 obtained by thermal oxidation. 
In the present example, the first insulation film on the Si substrate was 
composed of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN, T-SiN, LP-SiN or 
ECR-SiN, with a thickness of 1000, 2500, 5000, 7500 or 10000 .ANG.. 
The surface orientation of the Si substrate, thicknesses of the first and 
second Al films and heating conditions with the linear heater were 
selected same as in the example C1. 
As in the example C1, the transformation of the second Al film into 
monocrystalline state occurred when the substrate temperature was 
550.degree. C. or higher. Also as in the example C1, the measurement of 
element distribuion in the direction of depth, by Auger electron 
spectroscopy or secondary ion mass spectroscopy, indicated the diffusion 
of Si and Al at the interface between the insulation film on the substrate 
surface and the second Al film, when the substrate surface temperature was 
650.degree. C. or higher. 
In the example C3, the second Al was formed on the entire surface of the 
specimen as shown in cross section in FIG. 1A. In this example, an 
insulation film was formed on the second Al film as shown in FIG. 1B, and 
the heat treatment with the linear heater was conducted in the same manner 
as in the example C1. Said insulation film, on the second Al, was composed 
of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN, LP-SiN or EC-SiN, with thickness 
varied in 5 levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. 
The surface orientation of the Si substrate, thicknesses of the first and 
second Al films, and heating conditions of the linear heater were same as 
in the example C3. As in said example, the monocrystalline transformation 
of the second Al occurred when the substrate temperature was 550.degree. 
C. or higher. Also as in the example C3, the measurement of element 
distribution in the direction of depth, by Auger electron spectroscopy or 
secondary ion mass spectroscopy, indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 650.degree. C. 
or higher. 
EXAMPLE C5 
There was measured the area of transformation of the second Al into 
monocrystalline state by the heating with linear heater. The specimen 
structure was as shown in FIG. 5A, and same as that in the example B9 
employing laser heating, with a cross-sectional structure as shown in FIG. 
1A. The insulation film on the Si substrate is provided with a line of 
width L10, which was varied in 6 levels of 0.5, 1, 2, 5, 10 and 20 .mu.m. 
The surface orientation of the Si wafer was selected as (100) or (111). 
The insulation film was composed of SiO.sub.2 obtained by thermal 
oxidation, with thickness varied in 5 levels of 1000, 2500, 5000, 7500 and 
10000 .ANG.. Also the thickness of the Al deposited on the entire surface 
(second Al 4 in FIG. 1, or second Al 63 in FIG. 5A), was varied in 5 
levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. By taking combinations 
of the above-mentioned four conditions, namely Si substrate surface 
orientation, SiO.sub.2 film thickness, width L10 of the first Al film and 
thickness of the second Al, there were prepared 
2.times.5.times.8.times.6=480 specimens. 
Based on X-ray diffraction, electron beam diffraction pattern obtained by 
the conventional RHEED apparatus, and electron beam diffraction pattern 
and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope, the second Al film was identified as polycrystals consisting 
of crystal grains of several to ten microns, as in the examples B1 and C1. 
The heating was conducted in the same manner as in the example C1, with a 
moving speed of ca. 0.5, 1, 2, 5 or 10 cm/min. The substrate surface 
temperature directly below the linear heater, measured with a radiation 
thermometer employing a PbS probe, was selected as ca. 450.degree., 
550.degree., 600.degree., 650.degree. or 700.degree. C. The heating was 
conducted in hydrogen gas of atmospheric pressure. 
After the heat treatment, the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The electron beam diffraction patterns were dot patterns as 
shown in FIG. 14B, with intensities higher than before the heating, as in 
the example C1. The scanning .mu.-RHEED images utilizing the intensities 
of the 111 and 202 diffracted spots were similar to those shown in FIGS. 
17B and 17C. The direction of first Al (line direction) is parallel to the 
y-direction in FIG. 17A, while the heater scanning direction is parallel 
to the x-direction. The length of the area transformed into 
monocrystalline state can be determined from the measurement of L8 in FIG. 
17C. Though L8 in FIG. 17C is illustrated in the order of 10-20 .mu.m, it 
was in fact about 1 cm when the substrate temperature was 550.degree. C. 
or higher. Stated differently, the second Al film on SiO.sub.2 was 
transformed into monocrystalline state over a length of 1 cm, utilizing 
monocrystalline first Al as the seed. As in the example C1, the 
measurement of element distribution in the direction of depth, by Auger 
electron spectroscopy or secondary ion mass spectroscopy, indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 650.degree. C. or higher. 
EXAMPLE C6 
Specimens were prepared in the same manner as in the example C5, and were 
heat treated with the linear heater. Said specimens were however different 
in cross-sectional structure from those in the example C5. In the example 
C5, the second Al film was formed on the entire surface of the specimen, 
as shown in cross section in FIG. 1A or 5A. In this example, an insulation 
film was formed on the second Al, as shown in FIG. 1B or 5B, and the heat 
treatment with the linear heater was conducted in the same manner as in 
the example C5. The insulatiln film on the second Al, to be called the 
second insulation film, was composed of CVD-SiO.sub.2, PSG, BSG, BPSG, 
P-SiN or ECR-SiN, with a thickness of 1000, 2000, 5000 or 10000 .ANG.. The 
heating conditions with the linear heater were same as those in the 
example C1. After the heat treatment, the second insulation film was 
removed by etching, and the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope as in the example C5. The obtained results indicated, as in the 
example C5, that the second Al was transformed to monocrystalline state 
when the substrate temperature was 550.degree. C. or higher. As in the 
example C5, there were obtained the scanning .mu.-RHEED images similar to 
FIGS. 17B and 17C, and the area L8 of monocrystalline transformation was 
ca. 1 cm. Also as in the example C5, the measurement of element 
distribution in the direction of depth, by Auger electron spectroscopy or 
secondary ion mass spectroscopy, indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 650.degree. C. 
or higher. 
EXAMPLE C7 
In the examples C5 and C6, the insulation film formed on the Si substrate, 
in the structures shown in FIGS. 5A and 5B, was composed of SiO.sub.2 
obtained by thermal oxidation. In the present example, the insulation film 
on the Si substrate was composed of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN, 
T-SiN, LP-SiN or ECR-SiN, with thickness varied in 5 levels of 1000, 2500, 
5000, 7500 and 10000 .ANG.. Surface orientation of the Si substrate, 
thicknesses of the first and second Al films, and heating conditions with 
the linear heater were same as those in the example C1. 
As in the examples C5 and C6, the second Al was transformed to 
monocrystalline state when the substrate temperature was 550.degree. C. or 
higher. Also as in the examples C5 and C6, there were obtained the 
scanning .mu.-RHEED images similar to those in FIGS. 17B and 17C, with the 
transformed monocrystalline area L8 of ca. 1 cm. Further, as in the 
examples C5 and C6, the measurement of element distribution in the 
direction of depth, by Auger electron spectroscopy or secondary ion mass 
spectroscopy, indicated diffusion of Si and Al at the interface between 
the insulation film on the substrate surface and the second Al film, when 
the substrate surface temperature was 650.degree. C. or higher. 
EXAMPLE C8 
In the examples C1-C7, the first and second Al films were both composed of 
pure aluminum obtained by LP-CVD utilizing DMAH and hydrogen. 
In the present example, pure aluminum was replaced by Al-Si, deposited by 
the addition of Si.sub.2 H.sub.6 in the LP-CVD method employing DMAH and 
hydrogen. The Si content in the first and second Al-Si films was selected 
as 0.2, 0.5 and 1.0%. The heat treatment was conducted in the same manner 
as in the examples C1-C7. 
There were obtained similar results to those in the examples C1-C7. 
EXAMPLE C9 
In the examples C1-C7, the first and second Al films were formed by a 
LP-CVD method utilizing DMAH and hydrogen. In order to transform the 
second Al into monocrystalline state by heat treatment, the first Al has 
to be monocrystalline. The LP-CVD method has the advantage of being 
capable of depositing the first and second Al films in succession in the 
same apparatus, but the second Al film need not be formed by CVD as long 
as it is polycrystalline or amorphous. 
The present example employed the specimens and heating conditions same as 
those in the examples C1-C7, except that the second Al film alone was 
formed by sputtering. Based on X-ray diffraction, electron beam 
diffraction pattern obtained by the conventional RHEED apparatus, and 
electron beam diffraction pattern and scanning .mu.-RHEED image obtained 
by the scanning .mu.-RHEED microscope, the second Al film in the deposited 
state was identified as polycrystal consisting of crystal grains of about 
1 .mu.m or less. 
Heat treatment same as in the example C1-C7 provided results same as in 
said examples, that the second Al film was transformed into 
monocrystalline state when the substrate temperature was 550.degree. C. or 
higher. However, the transformed monocrystalline area L8, measured as in 
the examples C5-C7, was about 0.8 cm, which was shorter than 1 cm when the 
second Al was formed by CVD. Also as in the examples C1-C7, the 
measurement of element distribution in the direction of depth, by Auger 
electron spectroscopy or secondary ion mass spectroscopy, indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 650.degree. C. or higher. 
EXAMPLE C10 
Specimen structure and heating conditions were same as in the examples 
C1-C7. The first Al film was composed of Al-Si formed by LP-CVD employing 
DMAH, hydrogen and Si.sub.2 H.sub.6, while the second Al film was composed 
of pure aluminum formed by LP-CVD employing DMAH and hydrogen. 
The Si content in the first Al-Si film was selected as 0.2, 0.5 or 1.0%. 
There were obtained results similar to those in the examples C1-C7. 
EXAMPLE C11 
There were employed same specimen structure and heating conditions as in 
the examples C1-C7, except that the first Al film was composed of Al-Si 
formed by LP-CVD employing DMAH, hydrogen and Si.sub.2 H.sub.6, while the 
second Al film was composed of Al-Si formed by sputtering. The Si content 
in the first Al-Si was selected as 0.2, 0.5 or 1.0%. 
There were obtained results similar to those in the examples C1-C7. However 
the transformed monocrystalline area L8, measured as in the examples 
C5-C7, was ca. 0.8 cm which was shorter than 1 cm obtained when the second 
Al was formed by CVD. 
EXAMPLE D1 
Specimens were prepared in the same manner as in the examples C1-C11, and 
were subjected to heat treatment with lamp. 
FIG. 9 illustrates the heating method with lamp. 
The substrate 92 to be heated was placed on a substrate support 91, made of 
carbon. There was employed linear Xe lamp 93. The light therefrom was 
condensed by a reflector 94 into a line form on the substrate. The support 
91 was also heated by a heater (not shown) mounted on the bottom side 
thereof. The heating area 95 was moved on the substrate, by the movement 
of the lamp. The heating was conducted in hydrogen gas of atmospheric 
pressure. 
The heating area was moved by the movement of the support 91, with a moving 
speed of ca. 0.5, 1, 2, 5 or 10 cm/min. 
The substrate surface temperature in the heating area 95, measured with the 
radiation thermometer employing PbS probe, was ca.450, 550, 600, 650 or 
700.degree. C. 
With the heating as explained above, there were obtained results similar to 
those in the examples C1-C11. 
EXAMPLE E1 
Specimens were prepared in the same manner as in the examples C1-C11, and 
were heated by high frequency heating. 
FIG. 10 illustrates the heating method by high frequency heating. 
The substrate 103 to be heated was placed on a heating substrate support 
101, made of carbon. Also there were provided quartz plates 102. As shown 
in FIG. 10, the heating support, on which the substrate was placed, was 
heated by a high frequency coil (not shown) provided therearound. Since 
the quartz plates 102 are not heated by high frequency, a part 104 of the 
substrate was heated to the highest temperature. 
The heated area 104 moves on the wafer, by the movement thereof in a 
direction 105. The heating was conducted in hydrogen gas of atmospheric 
pressure. The moving speed was ca. 0.5, 1, 2, 5 or 10 cm/min. The 
substrate surface temperature of the heated area 104, measured by the 
radiation thermometer employing PbS probe, was ca. 450.degree., 
550.degree., 600.degree., 650.degree. or 700.degree. C. 
With the heating as explained above, there were obtained results similar to 
those in the examples C1-C11. 
EXAMPLE F1 
Specimens were prepared in the same manner as in the examples C1-C11, and 
were heat treated with an electron beam. 
FIG. 11 illustrates the heating method with electron beam. An electron beam 
113 from a filament 112 is focused into a line on a substrate 114 to be 
heated, by a focusing and scanning coil 115, and deflecting plates 115'. 
On said substrate, a linear portion 111 is heated to a high temperature. 
By the movement of the wafer in a direction 116, the heated portion 114 
also moves on the wafer. The heating was conducted in vacuum of a pressure 
of 10.sup.-8 Torr or lower. 
The moving speed of the substrate was ca. 0.5, 1, 2, 5 or 10 cm/min. The 
substrate surface temperature in the heated portion, measured with the 
radiation thermometer with PbS probe, was ca. 450.degree., 550.degree., 
600.degree.. 650.degree. or 700.degree. C. 
With the heating explained above, there were obtained results similar to 
those in the examples C1-C11. 
As explained in the foregoing examples, the monocrystalline Al can be 
formed on a substrate surface of any material. 
Also there can be obtained Al wirings with preferred characteristics for 
use in semiconductor devices, such as surface properties, antimigration 
resistance, adhesion to the underlying silicon etc. 
EXAMPLE G1 
The specimens used in the measurement, having a cross-sectional structure 
as shown in FIG. 1A, were prepared in the following manner. 
A Si wafer was subjected to thermal oxidation at 1000.degree. C. by 
hydrogen combustion (H.sub.2 : 4 1/min., O.sub.2 : 2 1/min.). The surface 
orientation of Si wafer was (100) or (111). The entire wafer was coated 
with photoresist and was exposed to a desired pattern by an exposure 
apparatus. After the photoresist was developed, reactive ion etching was 
conducted, utilizing the photoresist as a mask, to etch the underlying 
SiO.sub.2, thereby locally exposing the Si surface. 
Then an Al film was deposited by a low pressure CVD method, employing 
dimethylaluminum hydride and hydrogen, with a deposition temperature of 
ca. 270.degree. C. and a pressure of ca. 1.5 Torr in the reactor tube. At 
first selective Al deposition (first Al) was conducted solely on the 
exposed Si surface, then a surface modifying step was conducted by 
generating plasma in the low pressure CVD apparatus when the Al film 
thickness became equal to the SiO.sub.2 film thickness, and Al (second Al) 
was deposited on the entire surface. 
Following SiO.sub.2 patterns and Al film thicknesses were employed on the 
specimens. The SiO.sub.2 film thickness was varied in 5 levels of 1000, 
2500, 500, 7500 and 10000 .ANG.. The checkered pattern shown in FIG. 2A 
was used on the Si wafer, with size L1 varied in 8 levels of 0.25, 0.5, 1, 
2, 3, 5, 10 and 20 .mu.m. Thickness of the Al film deposited on the entire 
surface (second Al film 4 in FIG. 1) was varied in 3 levels of 100, 2500 
and 5000 .ANG.. By taking combinations of the above-mentioned four 
conditions, namely substrate surface orientation, SiO.sub.2 film 
thickness, checkered pattern size L1 and second Al film thickness, there 
were prepared 2.times.5.times.8.times.3=240 specimens. 
In the X-ray diffraction conducted after the deposition of the first and 
second Al films, all the specimens showed only an Al(111) peak, regardless 
of the SiO.sub.2 film thickness, size of the checkered pattern or second 
Al film thickness. Also in the observation of the electron beam 
diffraction pattern by the conventional RHEED apparatus with an electron 
beam diameter of 100 .mu.m-1 mm.phi., all the specimens showed ring-shaped 
patterns as shown in FIG. 14A. It was therefore confirmed that the Al 
deposited over the entire surface was polycrystals with an orientation 
(111). Also observation of the electron beam diffraction pattern in the 
scanning .mu.-RHEED microscope with an electron beam reduced to a diameter 
of 0.1 .mu.m provided a spot pattern as shown in FIG. 14B, though 
utilizing the diffracted spot intensity of the diffraction pattern 
provided an image as shown in FIG. 15A, wherein hatched areas indicate 
areas of high diffraction spot intensity, indicating polycrystalline state 
consisting of crystal grains of several to ten microns. 
In such specimens, the second Al was subjected to Al.sup.+ implantation by 
known ion implanting method, with an acceleration voltage of 50 kV and a 
dose of 5.times.10.sup.15 cm.sup.-2 or 1.times.10.sup.16 cm.sup.-2. 
Said ion implantation caused transformation of the second Al into amorphous 
or microcrystalline state, and said transformation was confirmed in the 
following manner. X-ray diffraction in the deposited state showed an 
Al(111) diffracted peak, but did no longer show the peak relating to Al 
after ion implantation. Also the electron beam diffraction in the 
conventional RHEED apparatus showed so-called hallow pattern which is 
neigher ring-shaped nor spot-shaped pattern. Thus, as a result of ion 
implantation, the Al or Al-Si film was transformed into a state which is 
not monocrystalline nor ordinary polycrystalline but amorphous or 
microcrystalline. 
The iron implanted specimens were heated treated in an electric over, at 
temperatures of 9 levels of 200.degree., 250.degree., 300.degree., 
350.degree., 400.degree., 450.degree., 550.degree. and 600.degree. C., for 
about 3 hours, in hydrogen gas atmospheric pressure. 
After the heat treatment in the above-mentioned conditions, the specimens 
were subjected to the observation of electron beam diffracted pattern and 
scanning .mu.-RHEED image in the scanning .mu.-RHEED microscope. 
All the specimens treated at 250.degree. C. or higher showed spot patterns 
as shown in FIG. 14B, with higher intensities than before the heat 
treatment, regardless of the Si wafer surface orientation, SiO.sub.2 film 
thickness, size of the checkered pattern or second Al film thickness. The 
diffraction pattern in FIG. 14B was identified, from the position of the 
diffracted spots, as being generated by the electron beam introduced from 
a direction [101]into the Al(111) plane. The scanning .mu.-RHEED images, 
obtained utilizing the intensities of a diffracted spot A (111 diffracted 
spot) and a spot C (202 diffracted spot) on the diffraction pattern in 
FIG. 14B were similar to those shown in FIGS. 15B and 15C, wherein areas 
of high diffraction spot intensity are hatched. The Al film deposited in 
the area of checkered pattern provided high intensities both for the spots 
A and C, indicating the transformation to monocrystalline state by heat 
treatment. In observation of the electron beam diffraction pattern in the 
conventional RHEED apparatus, all the specimens after heat treatment 
showed spot patterns indicating monocrystalline state, as shown in FIG. 
14B. 
Thus the second Al film, which had been polycrystals when deposited by the 
LP-CVD method, was transformed into monocrystalline state by heat 
treatment, after transformation into amorphous state by ion implantation. 
At the substrate surface temperature of 600.degree. C., the measurement of 
element distribution, by Auger electron spectroscopy or secondary ion mass 
spectroscopy, indicated diffusion of Si and Al at the interface of the 
insulation film on the substrate surface and the second Al film. 
EXAMPLE G2 
In the example G1, Al.sup.+ ions were implanted into the second Al film. In 
this example Si.sup.+ ions were implanted in the same specimens and 
procedures as in said example G1. 
Si.sup.+ ion implantation was conducted with an acceleration voltage of 80 
kV and a dose of 5.times.10.sup.15 cm.sup.-2 or 1.times.10.sup.16 
cm.sup.-2. 
There were obtained results similar to those in the example G1. The second 
Al was transformed by ion implantation into amorphous or microcrystalline 
state, and then to monocrystalline state at the heat treating temperature 
of 250.degree. C. or higher. 
EXAMPLE G3 
In contrast to Al.sup.+ ion implantation to the second Al in the example 
G1, the present example conducted implantation of H.sup.+ ions in the same 
specimens and procedure as in the example G1. 
H.sup.+ ion implantation was conducted with an acceleration voltage of 20 
kV and a dose of 5.times.10.sup.16 cm.sup.-2 or 1.times.10.sup.17 
cm.sup.-2. 
There were obtained results similar to those in the example G1. The second 
Al was transformed by ion implantation into amorphous or microcrystalline 
state, and then to monocrystalline state at the heat treating temperature 
of 250.degree. C. or higher. 
EXAMPLE G4 
In contrast to Al.sup.+ ion implantation to the second Al in the example 
G1, the present example conducted implantation of Ar.sup.+ ions in the 
same specimens and procedure as in the example G1. 
Ar.sup.+ ion implantation was conducted with an acceleration voltage of 80 
kV, and a dose of 5.times.10.sup.16 cm.sup.-2 or 5.times.10.sup.16 
cm.sup.-2. 
There were obtained similar results to those in the example G1. The second 
Al was transformed by ion implantation into amorphous or microcrystalline 
state, and then to monocrystalline state at the heat treating temperature 
of 250.degree. C. or higher 
EXAMPLE G5 
Specimens with a cross-sectional structure shown in FIG. 1A were prepared 
in the same manner as in the example G1, and were subjected to ion 
implantation and heat treatment. 
Different from the example G1, the via hole pattern shown in FIG. 2B was 
formed on the Si wafer, with size L2 varied in 5 levels of 0.25, 0.5, 1, 2 
and 5 .mu.m and size L3 varied in 5 levels of 1, 2, 5, 10 and 20 .mu.m. 
Thus there were prepared 25 different via hole patterns, taking 
combinations of said L2 and L3. The thicknesses of the SiO.sub.2 film and 
the Al film deposited on the entire wafer (second Al 4 in FIG. 1) were 
same as in the example G1. The specimens prepared as explained above were 
subjected to Al.sup.+ ion implantation in the same manner as in the 
example G1, then to heat treatment in the electric oven and subsequently 
observed. The Al.sup.+ ion implanting conditions and the heat treating 
conditions were same as in the example G1. 
Based on X-ray diffraction, electron beam diffraction pattern obtained in 
the conventional RHEED apparatus, and electron beam diffraction pattern 
and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope as in the example G1, the second Al in the deposited state by 
the LP-CVD method was identified, in any speciment, as polycrystals with 
an orientation (111), consisting of crystal grains of several to ten 
microns. 
After the Al.sup.+ ion implantation, it was confirmed, as in the example 
G1, that all the specimens were converted into amorphous or 
microcrystalline state. 
Then the heat treatment in the electric oven was conducted in the same 
conditions as in the example G1, and the electron beam diffraction pattern 
and the scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The scanning .mu.-RHEED images indicated, as in the example 
G1, that all the specimens treated at 250.degree. C. or higher were 
transformed into monocrystalline state, regardless of the surface 
orientation of the Si wafer, size of the checkered pattern or second Al 
film thickness. Also as in the example G1, the measurement of element 
distribution in the direction of depth, by Auger electron spectroscopy or 
secondary ion mass spectroscopy, indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film when the substrate surface temperature was 600.degree. C. 
or higher. 
EXAMPLE G6 
In contrast to Al.sup.+ ion implantation into the second Al in the example 
G5, the present example conducted Si.sup.+ ion implantation with the same 
specimens and procedure as in the example G5. 
The Si.sup.+ ion implanting conditions were same as those in the example 
G2. 
There were obtained similar results as those in the example G5, wherein the 
second Al was transformed by ion implantation into amorphous or 
microcrystalline state, and into monocrystalline state at the heat 
treating temperature of 250.degree. C. or higher. 
EXAMPLE G7 
In contrast to the example G5 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted H.sup.+ ion implantation with the 
same specimens and procedure as in the example G5. 
The H.sup.+ ion implanting conditions were same as those in the example G3. 
There were obtained similar results as those in the example G5, wherein the 
second Al was transformed by ion implantation into amorphous or 
microcrystalline state, and into monocrystalline state at the heat 
treating temperature of 250.degree. C. or higher. 
EXAMPLE G8 
In contrast to the example G5 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted Ar.sup.+ ion implantation with 
the same specimens and procedure as in the example G5. 
The Ar.sup.+ ion implanting conditions were same as those in the example 
G4. 
There were obtained similar results as those in the example Gl, wherein the 
second Al was transformed by ion implantation into amorphous or 
microcrystalline state, and into monocrystalline state at the heat 
treating temperature of 250.degree. C. or higher. 
EXAMPLE G9 
Specimens of a cross-sectional structure as shown in FIG. 1A were prepared 
in the same manner as in the example G1, and were subjected to ion 
implantation and heat treatment. Different from the example G1, the 
line-and-space pattern shown in FIG. 2C was formed on the Si wafer, with 
the size L4 varied in 5 levels of 0.25, 0.5, 1, 2 and 5 .mu.m and size L5 
in 5 levels of 1, 2, 5, 10 and 20 .mu.m. Thus 25 different line-and-space 
patterns were prepared by taking the combinations of L4 and L5. The 
thicknesses of the SiO.sub.2 film and the Al deposited on the entire 
surface (second Al 4 in FIG. 1) were same as in the example G1. 
The specimens prepared as explained above were subjected to Al.sup.+ ion 
implantation in the same manner as in the example G1, then to heat 
treatment in the electric oven and were observed. The Al.sup.+ ion 
implanting conditions and heat treating conditions were same as those in 
the example G1. 
Based on X-ray diffraction, electron beam diffraction pattern obtained in 
the convetional RHEED apparatus, and electron beam diffraction pattern and 
scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED microscope, 
the Al deposited on the entire surface (second Al) in any specimen was 
identified, as in the example G1, as polycrystals with an orientation 
(111), consisting of crystal grains of several to ten microns. 
It was also confirmed, as in the example G1, that all the specimens were 
transformed into amorphous or microcrystalline state by Al.sup.+ ion 
implantation. 
Then heat treatment with the electric oven was conducted in the same manner 
as in the example G1, and the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The scanning .mu.-RHEED image indicated, as in the example G1, 
that all the specimens treated at 250.degree. C. or higher were 
transformed to monocrystalline state regardless of the Si wafer surface 
orientation, SiO.sub.2 film thickness, size of the checkered pattern or 
second Al film thickness. Also as in the example G1, the measurement of 
element distribution in the direction of depth, by Auger electron 
spectroscopy or secondary ion mass spectroscopy, indicated diffusion of Si 
and Al at the interface between the insulation film on the substrate 
surface and the second Al film, when the substrate surface temperature was 
600.degree. C. or higher. 
EXAMPLE G10 
In contrast to the example G9 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted Si.sup.+ ion implantation with 
the same specimens and procedure as in the example G9. 
The Si.sup.+ ion implanting conditions were same as those in the example 
G3. 
There were obtained similar results to those in the example G9, wherein the 
second Al was transformed into amorphous or microcrystalline state by ion 
implantation, and to monocrystalline state by heat treatment at 
250.degree. C. or higher. 
EXAMPLE G11 
In contrast to the example G9 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted H.sup.+ ion implantation with the 
same specimens and procedure as in the example G9. 
The H.sup.+ ion implanting conditions were same as those in the example G3. 
There were obtained similar results to those in the example G9, where the 
second Al was transformed into amorphous or microcrystalline state by ion 
implantation, and to monocrystalline state by heat treatment at 
250.degree. C. or higher. 
EXAMPLE G12 
In contrast to the example G9 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted Ar.sup.+ ion implantation with 
the same specimens and procedure as in the example G9. 
The Ar.sup.+ ion implanting conditions were same as in the example G4. 
There were obtained similar results to those in the example G9, wherein the 
second Al was transformed into amorphous or microcrystalline state by ion 
implantation, and to monocrystalline state by heat treatment at 
250.degree. C. or higher. 
EXAMPLE G13 
In the examples G1-G12, the second Al was formed on the entire surface of 
the speciment, as shown in cross section in FIG. 1A. In the present 
example, an insulation film was formed on the second Al of the specimens 
of the examples G1-G12 as shown in FIG. 1B, and ion implantation and heat 
treatment with the electric oven were conducted in the same manner as in 
the examples G1-G12. In this example, after the deposition of the first 
and second Al films, there were conducted the ion implantation and then 
the heat treatment in the electric oven. The conditions of ion 
implantation and heat treatment were same as in the examples G1-G12. The 
insulation film on the second Al film was composed of a SiO.sub.2 film 
obtained by normal pressure CVD (hereinafter expressed as CVD-SiO.sub.2), 
a boron-doped oxide film obtained by normal pressure CVD (BSG), a 
phosphor-doped oxide film obtained by normal pressure CVD (PSG), a boron- 
and phosphor-doped oxide film obtained by normal pressure CVD (BPSG), a 
nitride film obtained by plasma CVD (P-SiN), or a nitride film obtained by 
ECR apparatus (ECR-SiN). Said insulation film on the second Al will 
hereinafter be called the second insulation film. 
The thickness of the second insulation film was selected as 1000, 2000, 
5000 or 10000 .ANG.. The heat treating temperature was same as in the 
examples G1-G12. After the heat treatment, the second insulation film was 
removed by etching, and the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed, as in the examples G1-G12, in the 
scanning .mu.-RHEED microscope. There were obtained similar results to 
those in the examples G1-G12, indicating that the second Al was 
transformed into monocrystalline state when the substrate temperature was 
250.degree. C. or higher. Also as in the examples G1-G12, the measurement 
of element distribution in the direction of depth, by Auger electron 
spectroscopy or secondary ion mass spectroscopy, indicated diffusion of Si 
and Al at the interface between the insulation film on the substrate 
surface and the second Al film, when the substrate surface temperature was 
600.degree. C. or higher. 
EXAMPLE G14 
In the examples G1-G12, the second Al film was formed on the entire surface 
of the specimen, as shown in cross section in FIG. 1A. In the present 
example, an insulation film was formed on the second Al as shown in FIG. 
1B, and ion implantation and heat treatment with the electric over were 
conducted in the same manner as in the examples G1-G12. In contrast to the 
example G13 in which conducted in succession were the ion implantation, 
the deposition of the second insulation film and the heat treatment with 
the electric over, the present example conducted in succession the 
deposition of the first and second Al films, the deposition of the second 
insulation film, the ion implantation and the heat treatment with the 
electric oven. The conditions of ion implantation and heat treatment were 
same as in the examples G1-G12. The insulation film on the second Al was 
composed of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN or ECR-SiN, with 
temperature was same as in the examples G1-G12. After the heat treatment, 
the second insulation film was removed by etching, and the electron beam 
diffraction pattern and the scanning .mu.-RHEED image were observed, as in 
the examples G1-G12, by the scanning .mu.-RHEED microscope. There were 
obtained similar results to those in the examples G1-G12, and the second 
Al was transformed to monocrystalline state when the substrate temperature 
was 250.degree. C. or higher. Also as in the examples G1-G12, the 
measurement of element distribution in the direction of depth, by Auger 
electron spectroscopy or secondary ion mass spectroscopy, indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 600.degree. C. or higher. 
EXAMPLE G15 
In the examples G1-G14, the first insulation film formed on the Si 
substrate, as shown in FIG. 1A, was composed of SiO.sub.2 formed by 
thermal oxidation. In the present example, the insulation film on the Si 
substrate was composed of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN, T-SiN, 
LP-SiN or ECR-SiN, with a thickness of 1000, 2500, 5000, 7500 or 10000 
.ANG.. 
The thicknesses of the first and second Al films, and the ion implanting 
conditions were same as those in the examples G1-G14. 
As in the examples G1-G14, the second Al film was transformed into 
monocrystalline state when the substrate temperature was 250.degree. C. or 
higher. Also as in the examples G1-G14, the measurement of element 
distribution in the direction of depth, by Auger electron spectroscopy or 
secondary ion mass spectroscopy, indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 600.degree. C. 
or higher. 
EXAMPLE G16 
There was measured the area of monocrystalline transformation of the second 
Al film. The structure and cross section of the specimens are as shown in 
FIG. 18 and FIG. 1A. The insulation film on the Si substrate was provided 
with a gap of a width L10, in which monocrystalline Al (first Al) was 
formed. Said width was varied in 6 levels of 0.5, 1, 2, 5, 10 and 20 
.mu.m. The surface orientation of the Si wafer was selected as (100) or 
(111). The insulation film was composed of SiO.sub.2 formed by thermal 
oxidation, with a thickness varied in 5 levels of 1000, 2500, 5000, 7500 
and 10000 .ANG.. The thickness of the Al deposited on the entire surface 
(second Al film 4 in FIG. 1, or second Al film 63 in FIG. 18) was varied 
in 3 levels of 1000, 2500 and 5000 .ANG.. By taking combinations of the 
above-mentioned four parameters, namely the Si substrate surface 
orientation, SiO.sub.2 film thickness, width L10 of the gap in first Al 
and second Al film thickness, there were prepared 
2.times.5.times.6.times.3=180 different specimens. 
Based on X-ray diffraction, electron beam diffraction pattern obtained by 
the conventional RHEED apparatus, and electron beam diffraction pattern 
and scanning .mu.-RHEED image obtained by the scanning .mu.-RHEED 
microscope, the second Al was identified, as in the example G1, as 
polycrystals consisting of crystal grains of several to ten microns. 
Al.sup.+ ions were implanted under the same conditions as those in the 
example G1, whereby the second Al was transformed into amorphous or 
microcrystalline state. Thereafter heat treatment in the electric oven was 
conducted in the same conditions as in the example G1. 
After the heat treatment, the electron beam diffraction pattern and the 
scanning .mu.-RHEED image were observed in the scanning .mu.-RHEED 
microscope. The electron beam diffraction provided, as in the example G1, 
a spot pattern as shown in FIG. 14B, with a higher intensity than before 
the heat treatment. The scanning .mu.-RHEED images obtained utilizing the 
111 and 202 diffracted spots were similar to those shown in FIGS. 17B and 
17C. FIG. 17A shows the pattern on the Si substrate, wherein the direction 
of first Al (line direction) is parallel to the y-direction in FIG. 17A. 
The length of the transformed monocrystalline area can be determined by 
measuring L8 in FIG. 17C. 
Though L8 is illustrated in the order of 10-20 .mu.m in FIG. 17C, it was in 
fact about 1 cm when the substrate temperature was 250.degree. C. or 
higher. Stated differently, the second Al on SiO.sub.2 was transformed 
into monocrystalline state over a length of 1 cm, utilizing 
monocrystalline first Al as the seed. Also as in the examples G1-G12, the 
measurement of element distribution in the direction of depth, by Auger 
electron spectroscopy or secondary ion mass spectroscopy, indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 600.degree. C. or higher. 
EXAMPLE G17 
In contrast to the example G16 employing Al.sup.+ ion implantation into the 
second Al, the present example conducted Si.sup.+ ion implantation with 
the same specimens and procedure as in the example G16. 
The Si.sup.+ ion implanting conditions were same as those in the example 
G2. 
There were obtained similar results to those in the example G16, wherein 
the second Al was transformed into amorphous or microcrystalline state by 
ion implantation, and further to monocrystalline state by heat treatment 
at 250.degree. C. or higher. 
EXAMPLE G18 
In contrast to the example G16 employing Al.sup.+ ion implantation to the 
second Al, the present example conducted H.sup.+ ion implantation with the 
same specimens and procedure as in the example G16. 
The H.sup.+ ion implanting conditions were same as those in the example G3. 
There were obtained similar results to those in the example G16, wherein 
the second Al was transformed into amorphous or microcrystalline state by 
ion implantation, and further to monocrystalline state by heat treatment 
at 250.degree. C. or higher. 
EXAMPLE G19 
In contrast to the example G16 employing Al.sup.+ ion implantation to the 
second Al, the present example conducted Ar.sup.+ ion implantation with 
same specimens and procedure as in the example G1. 
The Ar.sup.+ ion implanting conditions were same as those in the example 
G4. 
There were obtained similar results to those in the example G16, wherein 
the second Al was transformed into amorphous or microcrystalline state by 
ion implantation, and further to monocrystalline state by heat treatment 
at 250.degree. C. or higher. 
EXAMPLE G20 
In the examples G16-G19, the second Al was formed on the entire surface of 
the specimen, as shown in FIG. 18. In the present example, an insulation 
film was formed on the second Al film as shown in FIG. 19 and ion 
implantation and heat treatment with the electric oven were conducted in 
the same manner as in the examples G16-G19. In the present example, the 
deposition of the first and second Al films was followed by ion 
implantation and then heat treatment in the electric oven. The conditions 
of said ion implantation and heat treatment were same as in said examples 
G16-G19. The insulation film (second insulation film) on the second Al 
film was composed of CVD-SiO.sub.2, BSG, PSG, BPSG, P-SiN or ECR-SiN, with 
a thickness of 1000, 2000, 5000 or 10000 .ANG.. The heat treating 
temperature was same as in the examples G16-G19. After the heat treatment, 
the second insulation film was removed by etching, and the electron beam 
diffraction pattern and the scanning .mu.-RHEED image were observed in the 
scanning .mu.-RHEED microscope, as in the examples G16-G19. There were 
obtained similar results to those in said examples, wherein the second Al 
was transformed into monocrystalline state with heat treatment at 
250.degree. C. or higher. 
Also as in the examples G16-G19, the measurement of element distribution in 
the direction of depth, by Auger electron spectroscopy or secondary ion 
mass spectroscopy, indicated diffusion of Si and Al at the interface 
between the insulation film on the substrate surface and the second Al 
film, when the substrate surface temperature was 600.degree. C. or higher. 
EXAMPLE G21 
In the examples G16-G19, the second Al was formed on the entire surface of 
the specimen as shown in cross section in FIG. 1A. In the present example, 
an insulation film was formed on the second Al in-the specimens of the 
examples G1-G12, and ion implantation and heat treatment with the electric 
oven were conducted in the same manner as in the examples G16-G19. In 
contrast to the example G20 in which ion implantation, deposition of the 
second insulation film and heat treatment in the electric oven are 
conducted in succession, the present example conducted, after the 
deposition of the first and second Al films, the deposition of the second 
insulation film, ion implantation and heat treatment by the electric oven. 
The conditions of ion implantation and heat treatment were same as in the 
examples G16-G19. 
The insulation film on the second Al was composed of CVD-SiO.sub.2, BSG, 
PSG, BPSG, P-SiN or ECR-SiN, with a thickness of 500 or 1000 .ANG.. The 
heat treating temperature was same as in the examples G16-G19. After the 
heat treatment, the second insulation film was removed by etching, and the 
electron beam diffraction pattern and the scanning .mu.-RHEED were 
observed, as in the examples G16-G19, in the scanning results to those in 
the examples G16-G19, wherein the second Al was transformed into 
monocrystalline state when the substrate temperature was 250.degree. C. or 
higher. Also as in the examples G16-G19, the measurement of element 
distribution in the direction of depth, by Auger electron spectroscopy or 
secondary ion mass spectroscopy indicated diffusion of Si and Al at the 
interface between the insulation film on the substrate surface and the 
second Al film, when the substrate surface temperature was 600.degree. C. 
or higher. 
EXAMPLE G22 
In the examples G16-G21, the first insulation film formed on the Si 
substrate of the structure shown in FIG. 18 or 19 was composed of 
SiO.sub.2 obtained by thermal oxidation. In the present example, the 
insulation film on the Si substrate was composed of CVD-SiO.sub.2, BSG, 
PSG, BPSG, P-SiN, T-Sin, LP-SiN, or ECR-SiN, with a thickness varied in 5 
levels of 1000, 2500, 5000, 7500 and 10000 .ANG.. 
The thicknesses of the second Al film and of the second insulation film, 
and the ion implanting conditions, were same as those in the examples 
G16-G21. 
As in said examples, the second Al was transformed into monocrystalline 
state when the substrate temperature was 250.degree. C. or higher. Also as 
in said examples, the measurement of element distribution in the direction 
of depth, by Auger electron spectroscopy or secondary ion mass 
spectroscopy, indicated diffusion of Si and Al at the interface between 
the insulation film on the substrate surface and the second Al film, when 
the substrate surface temperature was 600.degree. C. or higher. 
EXAMPLE G23 
In the examples G1-G22, the first and second Al films were both composed of 
pure aluminum formed by a LP-CVD method employing DMAH (dimethylaluminum 
hydride) and hydrogen. In the present example, pure aluminum was replaced 
by Al-Si, deposited by the addition of Si.sub.2 H.sub.6 in LP-CVD in 
addition to DMAH and hydrogen. The Si content in the first and second 
Al-Si films was selected as 0.2, 0.5 or 1.0%. 
The heat treatment was conducted in the same manner as in the examples 
G1-G22, except that Al was replaced by Al-Si. 
There were obtained similar results to those in said examples G1-G22. 
EXAMPLE G24 
In the examples G1-G22, the first and second Al films were both formed by 
the LP-CVD method employing DMAH and hydrogen. In order to convert the 
second Al film into monocrystalline state by heat treatment, the first Al 
has to be monocrystalline. The LP-CVD method has the advantage of being 
capable of depositing the first and second Al films in succession in the 
same apparatus, but the second Al film need not be formed by CVD as long 
as it is polycrystalline or amorphous. 
The present example employed the same specimens and heat treating 
conditions as those in the examples G1-G22, but the second Al film alone 
was formed by sputtering. Based on X-ray diffraction, electron beam 
diffraction pattern obtained by the conventional RHEED apparatus, and 
electron beam diffraction pattern and scanning .mu.-RHEED image obtained 
by the scanning .mu.-RHEED microscope, the second Al film in the deposited 
state was identified as polycrystals consisting of crystal grains of 1 
.mu.m or smaller. 
By ion implantation and heat treatment in the same conditions as in the 
examples G1-G22, there were obtained similar results to those in said 
examples, wherein the second Al was transformed into monocrystalline state 
when the substrate temperature was 250.degree. C. or higher. However the 
transformed monocrystalline area L3, measured in the same manner as in the 
examples G16-G22, was about 0.8 cm, which was shorter than 1.0 cm obtained 
when the second Al film was formed by CVD. Also as in the examples G1-G22, 
the measurement of element distribution in the direction of depth, by 
Auger electron spectroscopy or secondary ion mass spectroscopy indicated 
diffusion of Si and Al at the interface between the insulation film on the 
substrate surface and the second Al film, when the substrate surface 
temperature was 600.degree. C. or higher. 
EXAMPLE G25 
There were employed same specimen structure and heating conditions as those 
in the examples G1-G22, but the first Al film was composed of Al-Si formed 
by LP-CVD employing DMAH, hydrogen and Si.sub.2 H.sub.6, while the second 
Al film was composed of pure aluminum formed by LP-CVD employing DMAH and 
hydrogen. The Si content in the first Al-Si film was selected as 0.2, 0.5 
or 1.0%. 
There were obtained similar results to those in the examples G1-G22. 
EXAMPLE G26 
There were employed same specimen structure and heating conditions as in 
the examples G1-G22, but the first Al film was composed of Al-Si formed by 
LP-CVD employing DMAH, hydrogen and Si.sub.2 H.sub.6, while the second Al 
film was composed of Al-Si formed by sputtering. The Si content in the 
first Al-Si film was selected as 0.2, 0.5 or 1.0%. 
There were obtained similar results to those in the examples G1-G22. 
However the transformed monocrystalline area L8, measured as in the 
examples G16-G22, was 0.8 cm, which was shorter than 1.0 cm when the 
second Al was formed by CVD. 
As explained in detail in the foregoing, the present invention can achieve 
transformation into monocrystalline state by a heat treatment, even in an 
Al film present on SiO.sub.2, if said SiO.sub.2 is so patterned to expose 
a Si surface and monocrystalline Al is present on thus exposed Si surface. 
Said monocrystalline transformation can be achieved with heat treatment of 
a low temperature. Said transformed monocrystalline Al can be utilized in 
wirings and can improve the resistances to migration phenomena.