Method and apparatus for writing a line on a patterned substrate

Method and apparatus for writing a line on a patterned substrate in which a direct writing of a CVD line is performed on at least two of patterned films on a substrate in accordance with the thermal decomposition of a CVD raw material gas which is resulted from the radiation of a laser beam. The laser beam is controlled in its power dependent on the difference between thermal conductivities of the at least two of patterned films to avoid a disconnection of the CVD line, the occurrence of thinner portion thereof and so on.

FIELD OF THE INVENTION 
The invention relates to method and apparatus for writing a line on a 
patterned substrate, and more particularly to method and apparatus for 
writing a line on a patterned substrate in which a thin film is deposited 
on a substrate having a surface which is patterned by different materials. 
BACKGROUND OF THE INVENTION 
One of conventional apparatus for writing a line on a patterned substrate 
comprises a laser light source for radiating a laser beam, a CVD (Chemical 
Vapor Deposition) cell having a window through which the laser beam is 
passed, an inlet through which vapor of CVD raw material gas is supplied, 
and an outlet to which an exhaust gas treatment unit is connected, and an 
X-Y stage on which the CVD cell is provided. 
In operation, a substrate having a surface which is patterned by different 
materials is positioned, and the CVD raw material gas is supplied through 
the inlet into the CVD cell. At the same time, the laser light source is 
driven to radiate the laser beam which is focussed to pass through the 
window of the CVD cell so that the substrate is subject to the radiation 
of the laser beam therein. In the CVD cell, the CVD raw material gas is 
thermally decomposed due to a reaction at the interface of the gas and 
substrate so that a predetermined pattern of a line is deposited with the 
decomposed gas on the substrate in accordance with the scanning of the 
laser beam thereon. 
The above mentioned operation is described, for instance, on pages 957 to 
959 of "Appl. Phys. Lett. 39(12), Dec. 15, 1981" and on page 32 to 35 of 
"IEEE ELECTRON DEVICE LETTERS, VOL. EDL-5, NO. 2, February 1984". 
In the former, a Si wafer from which a thermal oxidation film of SiO.sub.2 
is partially removed is positioned in a gas atmosphere of SiH.sub.4, while 
Ar-ion laser beam scans the Si wafer to be heated up to a predetermined 
temperature. As a result, the SiH.sub.4 gas is thermally decomposed so 
that a direct writing of Si can be performed on the Si wafer. 
In the latter, a CMOS chip is subject to the radiation of Ar-ion laser beam 
to be formed with boron-doped poly-Si thereon so that a contact can be 
formed between the boron-doped poly-Si and Al wiring, thereby modifying an 
erroneous wiring in the CMOS chip. 
According to the conventional apparatus for writing a line on a patterned 
substrate, however, there are resulted following disadvantages. 
First of all, it is difficult to write a well defined thick line on a 
substrate in an expected high speed operation. This is why a radiation 
pattern of a laser beam is of a circular beam having Gaussian intensity 
distribution so that the scanning speed must be very high to shift the 
radiation position on the substrate prior to the occurrence of the thermal 
spread so as to provide a narrow width of a line thereon. Due to the high 
speed scanning of the laser beam, a thick line having a low wiring 
resistance can not be obtained. 
Secondly, there is liable to be resulted an undesirable thinner line on the 
substrate when the scanning speed of a laser beam is increased without 
varying a power of the laser beam. In order to avoid the phenomenon, if 
the scanning speed of a laser beam is increased simultaneously with the 
increase of a radiation power of the laser beam, the center portion of a 
line is damaged due to an excessive thermal energy, and a line is 
transversely spread so that a width thereof is larger than a specified 
line because a region in which a raw material gas is thermally decomposed 
is transversely enlarged. In order to allow the increase of the scanning 
speed of a laser beam, further, it is considered that a supply amount of 
the raw material gas must be increased. In such a case, a film quality of 
a line is deteriorated to result in the increase of the resistivity 
thereof. For these reasons, it is difficult to write a line on a substrate 
in a high speed without decreasing characteristics of a film quality, 
thickness, and width thereof. 
Thirdly, there is resulted a disconnection of a line or thinner line when 
the writing of a line is performed on a step portion of the substrate in a 
case where a minimum step moving distance of a scanning stage is nearly 
equal to a spot size of a laser beam so that an area on which the laser 
beams are overlapped in accordance with the moving of the stage is small. 
To avoid the disadvantage, a stage which has such a very fine minimum 
moving distance as sub-micron meter much smaller than a spot size of a 
laser beam must be adopted therein. Actually, however, it is not practical 
to utilize such a stage therein because the stage becomes very expensive, 
and the surrounding in which an apparatus for writing a line on a 
substrate including the stage is installed must be cared to maintain the 
performance thereof. 
Fourthly, it is difficult to form a contact connecting a Si line to Al 
wiring because the thermal conductivity of Al is larger than that of such 
insulator films as SiO.sub.2, SiN etc. by one figure. In more detail, even 
if the Al wiring is subject to the radiation of Ar-ion laser beam, the Al 
wiring is not heated up to a predetermined temperature by which a CVD of 
Si can be performed so that a good quality of Si-deposition is not 
obtained. 
Finally, a disadvantage similar to the fourth disadvantage mentioned above 
is observed in a contact of Si line for connecting Al wiring on the upper 
and lower surfaces of an insulator film or passivation film through a via 
hole provided thereinto which is indispensable to the formation of wiring 
for a multilayered LSI. In such a use, there is observed a further 
disadvantage that it is difficult to form the burying of Si into the via 
hole so as to be in contact with the Al wiring at the bottom thereof due 
to the bad coverage of Si lines which are written on the side wall of the 
via hole because it is difficult that the side wall of the via hole is 
directly heated up to a predetermined temperature by a laser beam. 
Such disadvantages that an uniform width of a direct-write line is 
difficult to be obtained on a substrate having different thermal 
conductivities by a laser CVD, that a good quality contact with Al wiring 
is difficult to be obtained, and that a deposition material is difficult 
to be buried into a via hole with a predetermined characteristic so that a 
good quality of a contact with Al wiring at the bottom of the via hole is 
difficult to be formed are occured not only in Si as mentioned before, but 
also in a case where one of CVDs of Mo, W, and W respectively induced from 
Mo(CO).sub.6, W(CO).sub.6, and WF.sub.6 is utilized. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the invention to provide method and 
apparatus for writing a line on a patterned substrate in which a well 
defined thick line is written directly on a patterned substrate with a 
high speed. 
It is another object of the invention to provide method and apparatus for 
writing a line on a patterned substrate in which a predetermined thickness 
of a line is written directly on a patterned substrate. 
It is a further object of the invention to provide method and apparatus for 
writing a line on a patterned substrate in which a disconnection of a line 
or thinner line is avoided to be written even if a minimum step moving 
distance of a scanning stage is nearly equal to a spot size of laser beam. 
It is a still further object of the invention to provide method and 
apparatus for writing a line on a patterned substrate in which a stable 
contact connecting a line of a selected material to Al wiring is obtained 
even if the thermal conductivity of Al is much larger than that of the 
selected material. 
It is a yet further object of the invention to provide method and apparatus 
for writing a line on a patterned substrate in which a good quality of a 
contact between Al wirings on the upper and lower surfaces is obtained. 
According to one aspect of the invention, a method for writing a line on a 
patterned substrate comprises steps of, 
applying a laser beam to a substrate positioned in an atomosphere of a CVD 
raw material gas, said substrate having a plurality of patterned films 
thereon, and 
scanning said substrate by said laser beam to form a line of a thin film on 
at least two of said plurality of patterned films in a predetermined 
scanning direction, 
wherein a condition under which said laser beam is applied to said 
substrate is controlled dependent on the difference between thermal 
conductivities of said at least two of said plurality of patterned films. 
According to another aspect of the invention, an apparatus for writing a 
line on a patterned substrate comprises, 
a laser beam source for radiating a laser beam, 
a CVD cell in which a substrate is positioned passed, said substrate having 
a plurality of patterned films thereon, 
an optical means for introducing said laser beam to said CVD cell, 
a gas supply means for supplying a CVD raw material gas into said CVD cell, 
means for setting a condition under which said laser beam is applied to 
said substrate so that a line is written on at least two of said plurality 
of patterned films due to the thermal decomposition of said CVD raw 
material, and 
a stage means on which said CVD cell is provided to be moved in the 
scanning direction so that said substrate in said CVD cell is scanned 
through said window by said laser beam, 
wherein said means for setting a condition is controlled to change said 
condition dependent upon the difference between thermal conductivities of 
said at least two of said plurality of patterned films.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Before describing an apparatus for writing a line on a patterned substrate 
in preferred embodiments according to the invention, a conventional 
apparatus for writing a line a patterned substrate as described before 
will be explained in more detail. 
In FIG. 1, there is shown the conventional apparatus for writing a line on 
a patterned substrate which comprises a laser light source (not shown) for 
radiating a laser beam, a CVD (Chemical Vapor Deposition) cell 12 having a 
window 13 through which the laser beam 23 is passed, an inlet 12A through 
which vapor of CVD raw material gas is supplied, and an outlet 12B to 
which an exhausted gas treatment unit is connected, and an X-Y stage 14 on 
which the CVD cell 12 is provided. 
In operation, a substrate 11 having a surface which is patterned by 
different materials is positioned, and the CVD raw material gas is 
supplied through the inlet 12A into the CVD cell 12. At the same time, the 
laser light source is driven to radiate the laser beam 23 which is 
focussed to pass through the window 13 of the CVD cell 12 so that the 
substrate 11 is subject to the radiation of the laser beam 23 therein. In 
the CVD cell 12, the CVD raw material gas is thermally decomposed due to a 
reaction at the interface of the gas and substrate 11 so that a 
predetermined pattern of a line is deposited with the decomposed gas on 
the substrate 11 in accordance with the scanning of the laser beam 23 
thereon. The longitudinal scanning of the laser beam is performed in 
accordance with the X-directional moving of the substrate 11 on the X-Y 
stage, while the transverse scanning of the laser beam 23 is performed in 
accordance with the Y-directional moving of the substrate 11 on the X-Y 
stage. 
In FIG. 2, there is shown a substrate 11 on which Al wiring 37 and an 
insulator film 33 having an opening aperture 39 are formed. As the 
substrate 11 moves towards the left direction on the X-Y stage 14, the 
substrate 11 is scanned in the right direction as shown by an arrow S by 
the laser beam 23 so that a line 34 is written on the insulator film 33 
through a CVD process in accordance with gas decomposed by the radiation 
of the laser beam 23. In the process, however, a thickness of the line 34 
is gradually decreased, as the scanning region approaches the Al wiring 
37. Further, the line 34 is disconnected on the side wall of a step 
portion 36 of the insulator film 33 as shown by an arrow D. The reasons 
why such phenomenons are occured are explained before. 
Next, there will be explained an apparatus for writing a line on a 
patterned substrate in a first embodiment according to the invention. FIG. 
3 shows the apparatus for writing a line on a patterned substrate which 
comprises a CVD cell 12 having a window 13 through which a laser beam 23 
is passed, an inlet 12A through which vapor of Mo(CO).sub.6 is supplied 
from a gas supply source 29, and an outlet 12B to which an exhausted gas 
treatment unit 30 is connected, an X-Y stage 14 on which the CVD cell 12 
is provided, a controller 15 for controlling the X-Y stage 14 to move in 
two directions orthogonal to each other, an Ar-ion laser means 17 for 
radiating a laser beam, a pulse modulator 18 for pulse-modulating the 
laser beam, an intensity modulator 19 for intensity-modulating the laser 
beam, a dichroic mirror 20 by which the laser beam is reflected and 
through which a predetermined wavelength of light is passed, a lens 16 for 
focussing the laser beam to be a predetermined spot size on a substrate 11 
positioned in the CVD cell 12, a camera 21 for the monitor of the 
substrate 11 by receiving light which is passed through the dichroic 
mirror 20, and a television 22 for displaying the substrate 11 on which a 
line is written in accordance with the deposition of Mo. 
Operation 1 (intensity modulation) 
It is assumed that a Si substrate 11 which is covered with a SiO.sub.2 film 
in accordance with the thermal oxidation on which Al wiring is provided. 
Such a substrate 11 is positioned in the CVD cell 12 into which vapor of 
Mo(CO).sub.6 carried by Ar gas is introduced through the inlet 12A from 
the gas supply source 29. The laser beam radiated from the Ar-ion laser 
means 17 is reflected by the dichroic mirror 20 and is focussed by the 
lens 16 to pass through the window 13 so that the substrate 11 is locally 
subject to the radiation of the laser beam 23, thereby resulting in the 
deposition of Mo thereon in accordance with a local heating thereof. In 
the circumstance, a direct writing of Mo is performed to form a line on 
the substrate 11 when the substrate 11 is moved in a direction of the line 
in accordance with the drive of the X-Y stage 14. A written portion of the 
substrate 11 is directly observed through the dichroic mirror 20 by means 
of the camera 21 and television 22. In observing the written portion of Mo 
thereon, the frequency and intensity modulations are performed 
respectively by the pulse modulator 18 and intensity modulator 19, while 
the scanning speed of the laser beam 23 is controlled by the controller 
15. 
As mentioned before, the substrate 11 comprises the SiO.sub.2 film having a 
small thermal conductivity and Al wiring having a large thermal 
conductivity both provided on the surface thereof. As a matter of fact, 
the thermal conductivity of aluminum is 150 times that of SiO.sub.2. 
Therefore, if the laser beam 23 scans the Al wiring in the same scanning 
speed and intensity of light as those of a laser beam by which the 
SiO.sub.2 film is scanned, a predetermined amount of heat which is 
required for performing a CVD of Mo on the Al wiring is dissipated through 
the Al wiring due to the high thermal conductivity thereof so that a 
direct writing of Mo is difficult to be performed on the Al wiring or in 
the vicinity thereof. As a result, an electric contact between the Al 
wiring and a written line of Mo can not be obtained, and a direct writing 
of Mo can not be performed to cross over the Al wiring. 
In the operation 1 in the first embodiment, a power of the laser beam 23 is 
increased on the Al wiring by a predetermined amount larger than that on 
the SiO.sub.2 under the control of the intensity modulator 19, while the 
scanning speed of the laser beam 23 is maintained to be constant. To be 
more concrete, in a case where the scanning speed of the laser beam 23 is 
fixed to be 4 .mu.m/s, a power of the laser beam 23 is controlled to be 
approximately 300 mW to write a line of Mo having a width of approximately 
7 .mu.m and thickness of approximately 150 nm on the SiO.sub.2, film, 
while a power of the laser beam 23 is increased to be approximately 700 mW 
to write a line of Mo having a width of approximately 7 .mu.m and 
thickness of approximately 120 nm on the Al wiring. As a result, a stable 
electric contact can be obtained between a written line of Mo and Al 
wiring. 
Operation 2 (pulse modulation) 
The same substrate 11 as in the operation 1 is utilized in the operation 2. 
A scanning speed of the laser beam 23 is fixed to be 4 .mu.m/s, and a 
power of the laser beam 23 is controlled to be 700 mW when the pulse 
modulation of the laser beam 23 is not performed, and not to be changed 
before and after a pulse modulation. Under the condition described here, a 
pulse modulation in which a pulse width of the laser beam 23 is 5 .mu.S, 
and a repetition frequency thereof is 10 KHz is performed so that a line 
of Mo having a width of approximately 6 .mu.m and thickness of 250 nm is 
written on the SiO.sub.2 film, while a pulse modulation in which a 
repetition frequency of the laser beam 23 is increased up to 100 KHz under 
the control of the pulse modulator 18 is performed to increase a mean 
value of the intensity of the laser beam 23 so that a line of Mo having a 
width of approximately 6 .mu.m and thickness of approximately 200 nm is 
written on the Al wiring. 
Alternatively, a pulse modulation in which a pulse width of the laser beam 
23 is increased up to 50 .mu.S without varying the repetition frequency 
thereof is performed to increase a mean value of the intensity of the 
laser beam 23 is performed so that a line of Mo having a width of 
approximately 6 .mu.m and thickness of approximately 200 nm is written on 
the Al wiring. 
Operation 3 (control of scanning speed) 
The same substrate 11 as in the operations 1 and 2 is utilized in the 
operation 3. When a power of the laser beam 23 is fixed to be 300 mW, a 
scanning speed of the laser beam 23 is controlled to be 4 .mu.m/S on the 
SiO.sub.2 film so that a line of Mo having a width of approximately 7 
.mu.m and thickness of approximately 150 nm is written thereon, while a 
scanning speed of the laser beam 23 is lowered to be 1 .mu.m/S on the Al 
wiring in accordance with the drive of the X-Y stage 14 under the control 
of the controller 15 so that a line of Mo having a width of approximately 
7 .mu.m and thickness of approximately 120 nm is written directly thereon. 
Operation 4 (pulse modulation) 
The operation 4 is different from the operation 2 in that a pulse width of 
the laser beam 23 and repetition frequency thereof are simultaneously 
controlled to provide a constant mean value of the intensity of the laser 
beam 23 in the operation 4, while the former and latter are separately 
controlled in the operation 2. 
In the operation 4, a ceramic substrate 11 which is covered with a 
polyimide film on which Au wiring is patterned is utilized. In other 
words, it is said that the substrate 11 comprises the polyimide film 
having a small thermal conductivity and the Au wiring having a large 
thermal conductivity. The thermal conductivity of Au is 2000 times that of 
polyimide and one and half times that of aluminum. When a mean value of 
the intensity of the laser beam 23 is fixed to be 50 mW after a pulse 
modulation thereof is performed, and a scanning speed of the laser beam 23 
is also fixed to be 4 .mu.m/S, a repetition frequency thereof is 
controlled to be 10 KHz on the polyimide film so that a line of Mo having 
a width of approximately 10 .mu.m and thickness of approximately 500 nm is 
written directly thereon, while a repetition frequency of the laser beam 
23 is increased to be 200 KHz on the Au wiring to provide a higher peak 
intensity of the laser beam 23, and a pulse width thereof is narrowed, 
although a mean value of the intensity of the laser beam 23 is maintained 
to be constant so that a line of Mo having a width of approximately 10 
.mu.m is written directly thereon. 
Throughout the operations 1 to 4 in the first embodiment according to the 
invention, the Ar-ion laser means 17 is used to radiate a CW (Continuous 
Wave) laser beam. However, another means radiating a pulse beam may be 
added to the Ar-ion laser means 17 as described in a following second 
embodiment according to the invention. 
In FIG. 4, there is shown an apparatus for writing a line on a patterned 
substrate in the second embodiment according to the invention wherein like 
parts are indicated by like reference numerals in FIG. 3 so that repeated 
explanations are omitted here, provided that the apparatus for writing a 
line on a patterned substrate further comprises a movable mirror 24 which 
can be shifted to be positioned on a light path of the laser beam from the 
Ar-ion laser means 17, a mirror 25 for reflecting light in a predetermined 
direction, a YAG laser means 26 or radiating a pulse laser beam, a 
wavelength converter 41 for converting a wavelength of the pulse laser 
beam from the YAG laser means 26, and an intensity modulator 19B for 
intensity-modulating the pulse laser beam supplied from the wavelength 
converter 41. The intensity modulator which is positioned at the next 
stage of the pulse modulator 18 is changed to be indicated by a reference 
numeral "19A" in place of "19" in FIG. 3. 
In operation, the movable mirror 24 is shifted from a dotted line to a 
solid line to be positioned on the light path of the laser beam from the 
Ar-ion laser means 17. The YAG laser means is controlled to radiate a 
pulse laser beam having a repetition frequency of 1 KHz, a pulse width of 
approximately 20 ns, and a radiation intensity of 1 MW at the peak 
thereof. Before the movable mirror 24 is shifted to be positioned on the 
light path of the laser beam from the Ar-ion laser means 17, a line of Mo 
is written directly on the SiO.sub.2 film of the substrate 11 in 
accordance with the radiation of the laser beam 23 from the Ar-ion laser 
means 17. Next, the movable mirror 24 is shifted as described before so 
that the pulse laser beam is introduced through the mirror 25 and movable 
mirror 24, and further the dichroic mirror 20 to the CVD cell 12 to be as 
the pulse laser beam 23. The laser beam 23 is of a large power at the peak 
thereof and a narrow pulse width as described before so that Al wiring 
having, for instance, a width of 10 .mu.m can be subject to the radiation 
of the pulse laser beam 23 transiently, thereby being heated locally up to 
a predetermined temperature. As a result, a good quality of Mo CVD is 
performed on the Al wiring so that a contact between the line of Mo formed 
on the SiO.sub. 2 film beforehand and the Al wiring can be formed with a 
good characteristic, for instance, of a contact resistance value of 
approximately 200.OMEGA.. 
In another operation, a via hole provided into a PSG insulator film on a 
substrate is buried with a CVD of Mo to connect a line of Mo on the PSG 
insulator film to Al wiring. At first, the Ar-ion laser means 17 is driven 
to radiate Ar-ion laser beam having no pulse modulation, but an intensity 
of approximately 0.3 MW/cm.sup.2. In the circumstance, a scanning speed of 
the laser beam 23 is controlled to be 10 .mu.m/S so that a line 34 of Mo 
is written directly on a PSG insulator film 33 having a step portion 36 
and via hole 39 as shown in FIG. 5A wherein a substrate 11 which is 
covered with the PSG insulator film 33 on which Al wiring 37 is provided. 
Next, when the laser beam 23 approaches the via hole 39 as shown in FIG. 
5B, the laser beam from the Ar-ion laser means 17 is interrupted by the 
movable mirror 24 to be shifted to a solid line, while the pulse laser 
beam from the YAG laser means 26 is converted in regard to wavelength in 
the wavelength converter 41 to have a second harmonic light of 532 nm 
which is introduced to the CVD cell 12. The pulse laser beam 23 thus 
introduced is of a pulse width of 20 ns and a peak intensity 1.1 
MW/cm.sup.2. By use of such a pulse laser beam, a direct writing of Mo can 
be performed even in the vicinity of the via hole 39 in which heat is 
dissipated due to a large thermal conductivity of the Al wiring 37, 
although a temperature at which a CVD of Mo is performed is not obtained 
in a conventional manner. Further, when the laser beam 23 reaches the via 
hole 39 as shown in FIG. 5C, the via hole 39 is continued to be subject to 
the radiation of the pulse laser beam 23 for approximately 60 seconds so 
that the via hole 39 is completely burried with Mo, thereby providing a 
good quality of a contact at the bottom thereof. A resistance value of the 
contact thus formed is approximately 30.OMEGA. which is a satisfactory 
value applicable to a wiring of MOS LSI. 
The same operation as described above is applicable to an insulator film 33 
having a step portion 36 to write a line 34 of Mo directly thereon as 
shown in FIG. 6 so that no disconnection of the line 34 is occured. 
In FIG. 7, there is shown an apparatus for writing a line on a patterned 
substrate in a third embodiment according to the invention. The apparatus 
for writing a line on a patterned apparatus is different mainly from one 
in the first embodiment according to the invention in that a beam shape 
converter 27 provided on a rotary stage 28 is added thereto, while the 
pulse modulator 18 and intensity modulator 19 are excluded therefrom. In 
the present embodiment, a substrate 11 of Si LSI which is provided with 
poly-Si wiring layer on which SiN insulator layer is formed is positioned 
in the CVD cell 12. Circular Gaussian beam radiated from the Ar-ion laser 
beam 17 is converted in the beam shape converter 27 into an elliptical 
elongated Gaussian beam which is then reflected by the mirror 25. The 
elliptical laser beam thus reflected is focussed through the window 13 on 
the substrate 11 by the lens 16. The beam shape converter 27 includes two 
pieces of cylindrical lenses 27a and 27b to have a construction of a beam 
expander such that a vertical beam diameter is enlarged 5 times an 
original beam diameter, while a horizontal beam diameter remains 
unchanged. CVD raw material gas of Mo(CO).sub.6 which is diluted with Ar 
gas is supplied from the gas supply source 29 to the CVD cell 12. The 
partial pressure of Mo(CO).sub.6 is 1 Torr, and the total pressure of the 
gas is 1 atmospheric pressure. After the reaction of the gas in the CVD 
cell 12, the exhausted gas is treated in the exhaust gas treatment unit 30 
to provide no pollution. The X-Y stage 14 is controlled to provide a 
predetermined scanning speed of the laser beam 23 and a predetermined 
scanning direction of the laser beam 23 so that a direction, pattern etc. 
of a written line are defined. On the other hand, the rotary stage 28 
rotates the beam shape converter 27 on the light axis of the laser beam so 
that the line of apsides of the focussed elliptical laser beam aligns in 
regard to a scanning direction of the S-Y stage 14. 
In operation, a substrate 11 is processed to. have a via hole provided into 
SiN insulator film on poly-Si layer, and is positioned on a predetermined 
place in the CVD cell 12. Next, the X-Y stage 14 is driven to move the 
substrate 11 in a predetermined direction so that the laser beam 23 is 
focussed on the via hole of the substrate 11. As a matter of course, the 
line of apsides of the focussed elliptical laser beam 23 aligns in regard 
to the scanning direction of the X-Y stage 14. At this moment, raw 
material gas is supplied from the gas supply source 29 to the CVD cell 12. 
After such a preparatory stage, the laser beam is radiated from the Ar-ion 
laser means 17, while the X-Y stage 14 is controlled to be moved, thereby 
providing a predetermined scanning speed of the laser beam 23. Thus, a CVD 
line of Mo is written directly on the SiN insulator layer to connect the 
poly-Si wirings. 
A comparison between the operations in which an elliptical and circular 
laser beams are utilized is explained as follows. 
It is assumed that a spot size of the circular laser beam is 2 .mu.m in its 
diameter, while a spot size of the elliptical laser beam is 10 .mu.m in 
its line of apsides and 2 .mu.m in its minor axis. Further, a minimum step 
moving distance of the X-Y stage 14 is assumed to be 1 .mu.m. 
In the use of the circular laser beam, a good quality of wiring having a 
width of 5 .mu.m and thickness of 0.5 .mu.m, and a resistivity of 30 
.mu..OMEGA.cm is obtained under the condition that a scanning speed is 6 
.mu.m/S, and the amount of a radiation light is 500 mW. When the scanning 
speed is increased without varying the radiation intensity, the thickness 
of the wiring is decreased, and a disconnection of the wiring is occured 
at a step portion of the substrate. When the scanning speed is increased 
up to 10 .mu.m/S, and a power of the laser beam is increased up to 700 mW, 
a width of a line is expanded up to 7 .mu.m, and is varied in the 
longitudinal direction. Even worse, some concave portions which are 
considered to be damaged are found on the wiring. As a conclusion, a 
scanning speed at which a good quality of wiring is written by use of a 
circular beam is approximately 6 .mu.m/S. 
In the use of the elliptical laser beam, on the other hand, a good quality 
of wiring having the same thickness and width as in the circular laser 
beam, and having a low resistivity is formed at a scanning speed of 30 
.mu.m/S. At this time, a power of the radiation laser beam is 2W, and a 
good quality of Wiring can be obtained even by changing the power from 
1.5W to 2.5 W. Further, a frequency of resulting in a disconnection of 
wiring at a step portion of an insulator film is remarkably decreased as 
compared to the use of the circular laser beam. Even more, a disconnection 
of wiring is not found at a step portion of an insulator film as high as 
approximately 1.5 .mu.m. 
In the third embodiment described above, a cylindrical lens may be used as 
the beam shape converter 27 to convert the circular laser beam into an 
elliptical one, although a beam expander is used therein. In such a case, 
an adjustment of an optical system becomes a little complicated because a 
spreading angle of the laser beam is changed together with the conversion 
of the laser beam shape. Further, a beam splitter may be used as the beam 
shape converter 27 to convert an incident laser beam into a plurality of 
parallel lined beams so that an elongated shape of lined spots are defined 
on the substrate. Still further, although Mo(CO).sub.6 is used as a raw 
material gas, W(CO).sub.4 or WF.sub.6 may be used to write a line of W 
deposition, and SiH.sub.4 or SiH.sub.4 Cl.sub.2 may be used to write a 
line of Si deposition. 
In FIG. 4, there is shown an apparatus for writing a line on a patterned 
substrate in the fourth embodiment according to the invention. The 
apparatus for writing a line on a patterned substrate is similar to one in 
the third embodiment, but is different therefrom in that the beam shape 
converter 27 is not provided with a rotary stage, the X-Y stage is 
replaced by an X stage 32, and the X stage 32 is provided on a rotary 
stage 31. In the apparatus for writing a line on a patterned substrate, an 
operation in which the line of apsides of an elliptical laser beam aligns 
in regard to the scanning direction of the laser beam is performed by the 
rotary stage 31. As a result, a moving unit is eliminated from an optical 
system for laser beam radiation so that a wiring position on a substrate 
is prevented from being deviated out of a specified position due to the 
movement of a light axis. Further, the construction of the apparatus 
becomes simplified, and the cost thereof is lowered because the line of 
apsides of an elongated laser beam aligns in regard to the scanning 
direction by means of the rotary stage 31, and the scanning direction is 
also set in the direction of wiring by means of the rotary stage 31. 
As clearly understood from the first to fourth embodiments according to the 
invention, the principle and operation of the invention will be explained 
as follows. 
When such a continuous wave laser beam as Ar-ion laser beam scans a 
substrate having patterned multilayers thereon from a region of a low 
thermal conductivity to a region of a high thermal conductivity without 
performing any of an intensity modulation of the laser beam and pulse 
modulation thereof, and changing even a scanning speed, a width of a CVD 
line is narrowed on the region of the high thermal conductivity, and a 
quality thereof is deteriorated thereon because the heat which is 
dissipated is increased so that a temperature which is required for CVD 
process is difficult to be reached on that region. For the purpose of 
writing an uniform width and good quality of a line directly on a 
substrate, the decrease of a temperature must be avoided in the region 
having a high thermal conductivity by adopting at lease one of an 
intensity modulation of the laser beam and pulse modulation thereof, and 
the control of a scanning speed of the laser beam so that a limitation in 
which a CVD process is not performed dependent upon a thermal conductivity 
of a region is eliminated. 
At first, an operation in which an intensity modulation of a continuous 
wave laser beam is performed without performing a pulse modulation 
thereof, and a scanning speed of the laser beam is fixed to be constant is 
explained. That is, when a laser beam begins to scan a region of a high 
thermal conductivity after that of a low thermal conductivity, an 
intensity of the laser beam is increased so that the dissipation of heat 
is compensated to provide the same area of a temperature as on a region of 
a low thermal conductivity where a CVD process can be performed. As a 
result, an uniform width and good quality of a CVD line can be written 
over regions having different thermal conductivities. 
Secondly, an operation in which a pulse modulation of a continuous wave 
laser beam is performed, and an intensity thereof and a scanning speed 
thereof are fixed to be constant is explained. That is, when a peak 
intensity of a pulse which is obtained from a continuous wave laser beam 
is fixed to be constant in a case where a repetition frequency of the 
pulse is changed, a mean value of the intensity of the laser beam becomes 
larger as a repetition frequency thereof is increased and a pulse width 
thereof becomes wider. Accordingly, when a pulse laser beam begins to scan 
a region of a high thermal conductivity after that of a low thermal 
conductivity, a repetition frequency thereof is increased, or a pulse 
width thereof is widen so that the dissipation of heat is compensated on 
the region of the high thermal conductivity. As a result, a temperature 
which is required for a CVD process is reached thereon so that an uniform 
width and good quality of a line can be written over regions of different 
thermal conductivities. 
Thirdly, an operation in which a scanning speed of a continuous wave laser 
beam is controlled without performing both an intensity modulation thereof 
and pulse modulation thereof is explained. That is, when a scanning speed 
of the laser beam is lowered, a time during which a substrate is heated 
per an unit area by the laser beam is increased. Accordingly, when a 
continuous wave laser beam to scan a region of a high thermal conductivity 
after that of a low thermal conductivity, a scanning speed of the 
continuous wave laser beam is lowered to increase a heating time per an 
unit area so that the dissipation of heat is compensated on that region. 
As a result, an uniform width and good quality of a CVD line can be 
written over regions of different thermal conductivities. 
Although one of an intensity modulation and pulse modulation of a 
continuous wave laser beam, and be performed simultaneously. 
A following explanation is a case where an intensity modulation of a 
continuous wave laser beam and pulse modulation thereof are combined to 
write a CVD line directly on a substrate. In more detail, a pulse of the 
continuous wave laser beam is controlled in regard to an intensity and 
pulse width such that a mean value of the intensity of the pulse, and the 
product of a pulse width and repetition frequency thereof are constant 
respectively. In such a case, a peak intensity of the pulse is increased, 
and the pulse width is shortened in its time, as the repetition frequency 
is increased. Accordingly, when a chopping frequency of the pulse is high, 
the peak intensity thereof is large, and the pulse width thereof is narrow 
so that a region of a substrate is repeatedly heated by a specified short 
period before a temperature up to which the region is heated is 
substantially lowered. As a result, an area of a region in which a CVD 
process can be performed is narrower than that of a region in which a 
pulse modulation of a continuous wave laser beam is not adopted. 
In a case where the difference of thermal conductivities of two regions is 
relatively large, when a continuous wave laser beam begins to scan a 
region of a high thermal conductivity after that of a low thermal 
conductivity, only a small spot is increased in the region up to a 
predetermined temperature by which a CVD process can be performed because 
the heat is dissipated therein due to the high thermal conductivity. 
Therefore, when an intensity of a continuous wave laser beam is increased, 
or a scanning speed thereof is lowered so that the temperature is 
increased in the region up to a predetermined temperature by which a CVD 
process can be performed, it is happened that an area of the region in 
which the temperature is more than the predetermined temperature is larger 
than an area in a region of a lower thermal conductivity in which a CVD 
process can be performed. For the reason, in a case where different kinds 
of materials having a large difference of thermal conductivities are 
adjacent to each other, a width of a line is liable to be larger in the 
region having a large thermal conductivity than in the region having a 
small thermal conductivity. In this respect, both an intensity modulation 
of a continuous wave and pulse modulation thereof are utilized so that an 
area which is heated up to a predetermined temperature to be required for 
a CVD process is narrower, as a chopping frequency thereof is increased as 
mentioned before. As a result, an uniform width and good quality of a CVD 
line can be written directly on a substrate by maintaining a mean value of 
the laser beam intensity to be unchanged, and by increasing a repetition 
frequency of the pulse modulation, when the laser beam begins to scan the 
region of the high thermal conductivity after that of the low thermal 
conductivity. 
Although the modulations of a continuous wave laser beam is explained 
above, a pulse laser beam may be used in place of the continuous wave 
laser beam so that a pulse width of the pulse laser beam can be shorter 
than that of a pulse modulation of the continuous wave laser beam, thereby 
allowing a more local and transient heating to be performed. Accordingly, 
a good quality of a line can be written even in a region having a large 
thermal conductivity. Further, much better quality of a line can be 
written in accordance with the increase of the heating effect when a pulse 
width of the pulse laser beam is shortened so that a portion which is 
subject to the laser beam radiation is heated only in a limited surface 
layer. The pulse laser beam may be not only an oscillation light of a 
pulse oscillation laser means, but also a light generated in a non-linear 
optical element like, for instance, a second harmonic wave in Q-switched 
YAG laser means. 
Next, an operation in which a circular laser beam is converted into an 
elliptical laser beam, the line of apsides of which is parallel or 
orthogonal to the scanning direction of the laser beam, is explained. 
When the line of apsides of the elliptical laser beam is parallel to the 
scanning direction of the laser beam, the radiation time of the laser beam 
is longer by a ratio of the line of apsides in regard to the minor axis 
thereof as compared to a case where a circular laser beam is utilized. As 
a result, a scanning speed of such an elongated laser beam as the 
elliptical laser beam can be faster by that ratio than a scanning speed of 
a circular laser beam in a case where intensities of the radiation laser 
beam are controlled to be the same level between the elongated and 
circular laser beams. For the reason, it becomes possible that a higher 
speed formation of wirings is performed without affecting the 
characteristics of a width, thickness and quality of a line. Further, when 
a line is written directly on a step portion of a substrate, the line of 
apsides of the elliptical line is controlled to be much longer than a 
minimum step moving distance of an X-Y stage without changing the minor 
axis thereof so that the laser beams are overlapped sufficiently in the 
scanning direction, thereby providing a stable line having no 
disconnection and thinner portion at the step portion of the substrate. 
On the contrary, when the line of apsides of the elliptical laser beam is 
orthogonal to the scanning direction of the laser beam, a wider line can 
be written so that a wiring pad having a large area can be formed in a 
short time. 
Although the invention has been described with respect to specific 
embodiment for complete and clear disclosure, the appended claims are not 
to thus limited but are to be construed as embodying all modification and 
alternative constructions that may occur to one skilled in the art which 
fairly fall within the basic teaching herein set forth.