Plasma reaction apparatus and plasma reaction

A process for depositing a film at a high rate and with superior step coverage properties, which comprises installing a pair of electrodes crossing with another pair of electrodes making a right angle with respect to the another pair, and applying a high frequency power differing in phase to the electrodes in order to apply a high frequency power having a Lissajous' waveform in the reaction space during the deposition of a film on a substrate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a plasma reaction apparatus, particularly 
an apparatus for depositing a film such as a semiconductor film and an 
insulation film. The present invention also relates to a plasma reaction 
method, particularly a process for depositing a film. 
2. Prior Art 
Conventionally known processes for depositing semiconductor films and 
insulation films include plasma CVD, sputtering, low pressure CVD, and 
photochemical vapor deposition. However, none of the enumerated processes 
satisfy both of the demands of high speed deposition and high step 
coverage at the same time. 
Accordingly, an object of the present invention is to provide a process for 
depositing a film, which enables the deposition of a film at a high speed 
and yet, with an excellent step coverage. Another object of the present 
invention is to provide an apparatus for depositing a film which realizes 
the film deposition process above. 
SUMMARY OF THE PRESENT INVENTION 
The present invention provides a plasma reaction apparatus, e.g. a film 
deposition apparatus, of a parallel planar type comprising electrodes 
being arranged in parallel with each other at a distance of 10 mm or less. 
The rate of film deposition can be increased by thus setting the 
electrodes. Furthermore, a film having an improved step coverage can be 
realized by irradiating an ultraviolet light to the electrode during the 
film deposition. In addition to the aforementioned constitution of the 
apparatus, two pairs of parallel planar type electrodes are placed in such 
a manner that one pair may cross the other pair making a right angle with 
respect to the other pair. In this manner, an electric field, e.g. an 
alternating electric field, can be applied in parallel with the substrate. 
A high frequency electric field (electric power) having a Lissajous' 
waveform is applied to the substrate from the two pairs of electrodes in 
order to stir and activate the reaction gas. In this manner, the rate of 
film deposition can be increased and the step coverage properties can be 
improved. 
A plasma reaction method in accordance with the present invention 
comprises: 
effecting a vapor phase reaction by applying an alternating electric power 
having a Lissajous' waveform from two pairs of electrodes arranged in such 
a manner that the two pairs may cross each other making a right angle with 
respect to each other, while irradiating an ultraviolet light thereto.

DETAILED DESCRIPTION OF THE INVENTION 
The high frequency electric field having a Lissajous' waveform is supplied 
from two pairs of electrodes arranged in such a manner that one of the 
pairs may cross the other making a right angle with respect to the other 
pair, by applying, to each pair of the electrodes, a high frequency 
electric power of same frequency but differing in phase. Each of the pairs 
of the electrodes is composed of a pair of parallel planar type 
electrodes. The high frequency electric power applied in differing phase 
preferably has the same frequency, or at a frequency as such that one may 
be a harmonic of the other. 
The plasma reaction apparatus, e.g. film deposition apparatus, comprises a 
pair of parallel planar type electrodes set at a small distance from each 
other and in parallel with a substrate to be placed in the apparatus. In 
this manner, the rate of film deposition can be considerably accelerated. 
Furthermore, the height of step coverage can be increased by irradiating a 
ultraviolet light. By applying a high frequency electric power having a 
Lissajous' waveform, the electrons and ions can be efficiently vibrated or 
rotated to enhance the stirring and the activation of the reaction gas. 
Thus, a high rate of film deposition and a film having excellent step 
coverage can be implemented. 
The present invention is illustrated in greater detail referring to 
non-limiting examples below with the attached figures. It should be 
understood, however, that the present invention is not to be construed as 
being limited thereto. 
EXAMPLE 1 
Referring to FIG. 1, an apparatus for depositing a film according to an 
embodiment of the present invention is described below. FIG. 1 shows the 
cross section view from the upper side of the film deposition apparatus 
according to the present invention. A substrate 19 is placed inside a 
vacuum chamber 11 whose pressure can be reduced by means of a vacuum 
system (not shown in the figure). The reaction gas and the dilution gas 
necessary for the film deposition process, or a doping gas and the like 
are supplied into the chamber 11 by a gas supply system (not shown in the 
figure). The reaction gas supplied into the chamber is activated by a high 
frequency electric power having a Lissajous' waveform applied by a pair of 
electrodes 12 and 13, and also by another pair of electrodes 15 and 16 
provided in such a manner that they make a right angle with respect to the 
pair of electrodes 12 and 13. Thus, in this case, it can be seen that the 
pair of electrodes 12 and 13 are arranged to make a right angle with the 
pair of electrodes 15 and 16, and they altogether make the two pairs of 
electrodes placed crossing with each other. 
A high frequency electric power (alternating electric field) is supplied to 
a pair of electrodes 12 and 13 by a high frequency power supply system 14 
comprising an oscillator, an amplifier, and a matching circuit. Similarly, 
a high frequency electric power (alternating electric field) is supplied 
to the other pair of electrodes 15 and 16 by a high frequency power supply 
system 17 also comprising an oscillator, an amplifier, and a matching 
circuit. The phases of the high frequency electric power supplied 
independently from each of the high frequency electric power supply 
systems 14 and 17 are adjusted by a phase lock mechanism 18 in such a 
manner that they may differ from each other. By thus controlling the phase 
difference, a high frequency electric power having a Lissajous' waveform 
can be applied to the reaction space having a substrate 19 placed therein. 
Thus, the reaction gas can be stirred and activated further by allowing 
the electrons or the ions to move in accordance with a Lissajous' figure. 
In general, the phase difference is set at an angle of 90.degree., but the 
phase difference is not only limited thereto. Furthermore, the phase 
difference can be varied as a function of time; i.e., the Lissajous' 
figure can be changed with time. In the apparatus according to the present 
invention, the high frequency power is supplied from the high frequency 
power supply systems 14 and 17 at a frequency of 50 MHz. The frequency of 
this high frequency power can be varied in the range of from 1 to 1,000 
MHz, and the supply systems may each supply power differing in frequency. 
However, the high frequency power systems preferably supply a power of the 
same frequency; otherwise, one of the power systems may supply a power at 
a frequency corresponding to a harmonic of the high frequency power 
supplied by the other power supply system. 
FIG. 2 is a cross section view of the film deposition apparatus shown in 
FIG. 1 along the line A-A'. Referring to FIG. 2, a pair of electrodes 15 
and 16 are shown therein and another pair of electrodes 12 and 13 are 
arranged in front and back of the sheet of FIG. 2. An ultraviolet light is 
irradiated to the substrate 19 from an ultraviolet light source 21 (a 
mercury vapor lamp) through a quartz window 23. Furthermore, a high 
frequency power (13.56 MHz) is applied between a mesh electrode 22 and a 
ground electrode (on which the substrate 19 is placed) 25 by a high 
frequency power supply system 24. Though not shown in the figure, a means 
is provided to heat the substrate 19 to a desired temperature. 
The mesh electrode and the ground electrode constitute a pair of parallel 
planar type electrodes. The distance between these electrodes is 
preferably set as small as possible. More preferably, the electrodes are 
placed at a distance of 10 mm or less from each other. The minimum 
distance between the electrodes is limited by the thickness of the 
substrate, the manner of supplying the gas, and the means of charging in 
and discharging out the substrate from the space between the electrodes. 
The film is deposited on the substrate 19 by plasma gas phase reaction 
effected by high frequency discharge between the mesh electrode 22 and the 
ground electrode 25 facing thereto, the energy supplied by ultraviolet 
light irradiated from the ultraviolet light source, and two forms of high 
frequency power having a Lissajous' waveform but differing in phases 
separately supplied from a pair of electrodes 15 and 16 and another pair 
of electrodes 12 and 13 crossing the pair of electrodes 15 and 16 making a 
right angle with respect thereto. 
The distance between the mesh electrode 22 and the ground electrode facing 
thereto is reduced in order to increase the rate of film deposition. For 
example, it is confirmed that the rate of film deposition can be enhanced 
in the case of depositing a silicon oxide film using a tetraethoxysilane 
(TEOS; Si(OC.sub.2 H.sub.5).sub.4) gas and oxygen. Furthermore, 
ultraviolet light is supplied in order to increase the height of step 
coverage, as well as to effectively decompose and activate organic silanes 
represented by TEOS and the like. 
EXAMPLE 2 
The present example relates to a process for depositing a silicon oxide 
(SiO.sub.2) film by using a film deposition apparatus illustrated in FIGS. 
1 and 2. Tetraethoxysilane (TEOS; Si(OC.sub.2 H.sub.5).sub.4) was used as 
the starting gas for the film deposition in this example, but other 
organic silanes having ethoxy groups can be used as well, for example, 
Si(OC.sub.2 H.sub.5).sub.4, Si.sub.2 O(OC.sub.2 H.sub.5).sub.6, Si.sub.3 
O.sub.2 (OC.sub.2 H.sub.5).sub.8, Si.sub.4 O.sub.3 (OC.sub.2 
H.sub.5).sub.10, and Si.sub.5 O.sub.4 (OC.sub.2 H.sub.5).sub.12. 
The film deposition is effected by applying high frequency power (50 MHz) 
to each of the two pairs of electrodes, i.e., to the pair of the 
electrodes 12 and 13, as well as to the pair of electrodes 15 and 16 which 
are crossed with the electrodes 12 and 13 in such a manner that one pair 
make a right angle with respect to the other pair. The high frequency 
power applied to one pair of the electrodes has a constant phase 
difference, generally 90 degrees, with respect to that applied to the 
other pair of the electrodes. In this manner, a high frequency power 
having a Lissajous' waveform can be supplied inside the chamber. 
Furthermore, a high frequency power is applied between the mesh electrode 
22 and the ground electrode 25 at a frequency of 13.56 MHz, and a 
ultraviolet light is irradiated from the ultraviolet light source 21 
comprising a mercury lamp to the substrate 19. Thus, a silicon oxide film 
can be deposited on the substrate 19. Preferably, the substrate is heated 
to a temperature range of from about 200 to 600.degree. C., preferably, to 
about 300.degree. C. The reaction pressure is set in the range of from 
0.01 to 10 Torr, preferably, in the range of from 0.1 to 1 Torr. 
By effecting the film deposition in this manner, the reaction gas can be 
stirred and activated. Hence, the decomposition of the reaction gas can be 
accelerated by the high frequency power having the Lissajous' waveform. 
Moreover, films can be deposited on the substrate at a high rate and with 
a high step coverage by supplying a high frequency power between the mesh 
electrode 22 and the ground electrode 25 facing thereto, and by supplying 
the ultraviolet light from the ultraviolet light source 21. 
In depositing a silicon oxide film by using an organic silane gas as in the 
process according to the present embodiment, in particular, carbon and 
oxygen can be reacted to form CO.sub.2 by irradiating ultraviolet light to 
the organic silane gas. Thus, carbon can be effectively removed from the 
silicon oxide film and discharged to the exterior to leave a high quality 
silicon oxide film free of carbon. The silicon oxide film fabricated by 
the process according to the present embodiment can be used, for example, 
as a gate insulation film of thin film transistors (TFTs), a passivation 
film of an IC, and an inter layer insulation film of an IC. 
Thus, as described in the foregoing, a high quality film having a high step 
coverage can be implemented by applying a high frequency power having a 
Lissajous' waveform and by irradiating ultraviolet light. In addition, the 
film can be obtained at a high film deposition rate by narrowing the 
distance between the pair of electrodes 22 and 25 which are provided for 
applying a high frequency electric field perpendicular to the substrate. 
EXAMPLE 3 
The present embodiment comprises, in addition to the film deposition 
process of Example 2 comprising irradiating ultraviolet light during the 
film deposition, annealing the thus deposited film while irradiating 
ultraviolet light to the deposited film. In this manner, for example, the 
interface properties of the gate insulation film of a TFT can be 
considerably improved. Furthermore, the effect of annealing can be further 
enhanced by heating the film in the temperature range of from about 200 to 
500.degree. C., preferably, at about 350.degree. C., while irradiating the 
ultraviolet light. 
EXAMPLE 4 
The present embodiment comprises depositing a Si film using the film 
deposition apparatus described in Example 1. The film can be deposited by 
using silane (SiH.sub.4) or any of the reaction gases generally used in 
the deposition of a non-single crystal silicon film and hydrogen gas, 
optionally together with a doping gas, such as phosphine (PH.sub.3) and 
diborane (B.sub.2 H.sub.6). 
EXAMPLE 5 
The present embodiment comprises depositing a silicon nitride (Si.sub.3 
N.sub.4) film by means of the film deposition apparatus described in 
Example 1. Silane (SiH.sub.4) and ammonia (NH.sub.4) are used as the 
reaction gases. In addition to the silicon oxide and silicon nitride films 
above, it is also possible to deposit PdTiO.sub.3 or TaO.sub.5 films by 
using the apparatus described in Example 1. It is also useful to effect 
the annealing by heating the film while irradiating ultraviolet light 
thereto as described in Example 3 above. 
EXAMPLE 6 
The present embodiment comprises a plurality of film deposition apparatuses 
described in Example 1. The film deposition apparatuses are parallel 
connected to give a constitution illustrated in FIG. 3. Referring to FIG. 
3, a common transportation chamber 31 for transporting substrates is 
provided in addition to the chambers 32 to 36 each equivalent to the film 
deposition apparatus described in Example 1. The constitution shown in 
FIG. 3, which shows the chamber only, comprises 5 sets of film deposition 
apparatuses illustrated in FIGS. 1 and 2 parallel connected via the 
transportation chamber 31. The transportation chamber 31 is connected with 
each of the chambers by a gate valve 37 equipped with a transportation 
mechanism for transferring the substrates. 
The film deposition process comprises transferring the substrate into the 
transportation chamber 31, and after evacuating the chamber to realize a 
high degree of vacuum therein, transferring the substrate from the 
transportation chamber 31 into a first chamber (for example, a chamber 32) 
also evacuated to a high degree of vacuum via the gate valve 37. The gate 
valve 37 is then shut to perform the predetermined process of film 
deposition. Upon completion of the film deposition or the annealing after 
the film deposition, the chamber is evacuated to a high degree of vacuum 
to transfer the substrate again into the transportation chamber 31 
evacuated to a high degree of vacuum. If necessary, film deposition is 
effected by transferring the substrate into a second chamber (for example, 
a chamber 33) in a manner similar to the operation employed in 
transferring the substrate into the first chamber 31. 
The constitution above is particularly effective in case of sequentially 
depositing different films. Not all the chambers necessarily have the same 
constitution as that described in example 1. If necessary, a sputtering 
apparatus, a plasma CVD apparatus or an ion implantation apparatus may be 
used. Also in such cases, the substrates are transported via a common 
chamber 31 evacuated to a high degree of vacuum to prevent mixing of 
different gases and impurities. 
Each of the chambers and the transportation chamber 31 are constructed 
independently from each other, and each of the chambers comprises a vacuum 
evacuation system consisting of a turbo-molecular pump or a cryopump. The 
vacuum evacuation system removes residual gas and impurities from the 
chamber. 
EXAMPLE 7 
FIG. 5 shows an embodiment of forming a thin film integrated circuit having 
at least one set of TFT by utilizing a multiobjective deposition system 
shown in FIG. 4. First of all, a multiobjective deposition system utilized 
in this embodiment is explained. In this embodiment, 101 and 106 are made 
as preliminary chambers loading and unloading a substrate. Here, 101 is a 
loader and 106 is an unloader of a substrate. 104 is a process chamber for 
performing rapid thermal anneal process (also referred to as RTA or RTP) 
by irradiation of infrared light for a short time, or performing 
preliminary heating. 103 is a process chamber for depositing a film mainly 
comprising aluminum nitride (alumioxide nitride is hereinafter called as 
aluminum nitride) or a silicon nitride film by a plasma CVD method. 104 is 
a process chamber for depositing a silicon oxide film by a plasma CVD 
method with utilizing TEOS as a main material. 105 is a process chamber 
for depositing an amorphous silicon film by a plasma CVD method. Each 
process chamber has an exhaustion means to make each process chamber low 
pressure and a gas introducing means to introduce a gas needed. 
Process of forming the thin film integrated circuit is to be explained as 
the following. First of all, a glass substrate 201 like Corning 7059 
(4.times.4 inches, 5.times.5 inches, or 5.times.6 inches) is carried to 
the preliminary chamber 101, and the preliminary chamber 101 is exhausted 
enough. It is preferable if this exhaustion is performed until pressure of 
the chamber 101 becomes the same as that of the loader 107 which has been 
exhausted enough. A gate valve 110 is opened, and the substrate in the 
preliminary chamber 101 is transported to the loader 107 by a robot arm 
108. A substrate 201 in FIG. 5 is indicated as 109 in FIG. 4. From now on, 
meaning of "a film deposited on a substrate" is included in the meaning of 
"a substrate". 
By opening a gate valve 112 between the preliminary chamber 101 and the 
reaction chamber 103 which has been exhausted to the same pressure, the 
substrate is transported to the reaction chamber 103. The gate valve 112 
is closed after the substrate is put into the reaction chamber 103. An 
aluminum nitride film 202 is formed by 2000 to 5000 .ANG. thickness by a 
plasma CVD method. This deposition is performed by utilizing Al(C.sub.4 
H.sub.9).sub.3, or by utilizing Al(CH.sub.3).sub.3 and N.sub.2. N.sub.2 O 
can be added in a small amount to alleviate distortion by thermal 
expansion. 
After the aluminum nitride film 202 is deposited, the reaction chamber 103 
is exhausted so that the reaction chamber 103 would be of the same 
exhaustion level as that of the loader 107. By opening the gate valve 112, 
the substrate is transported to the loader by the robot arm 108. The 
substrate is transported to the anneal chamber 104 which has been 
exhausted in the same way. Rapid thermal anneal (RTA) by irradiation of 
infrared light is performed in this anneal chamber 104. This annealing is 
performed in an atmosphere of nitrogen, ammonia (NH.sub.3), or dinitrogen 
monoxide (N.sub.2 O), rapidly heating an aluminum nitride film in a short 
time. This annealing makes the aluminum nitride film transparent, and 
improves insulating property and thermal conductivity of it. A silicon 
nitride film can be formed to prevent intrusion of impurities like natrium 
from the glass substrate to the semiconductor. In this case, the silicon 
nitride film is deposited by a plasma CVD method with substrate 
temperature 350.degree. C., at 0.1 Torr, and in a mixed atmosphere of 
SiH.sub.4 and NH.sub.3. 
The reaction chamber 104 is exhausted. The substrate is transported to the 
loader 107 which has been exhausted again, by the robot arm 108. And then, 
the substrate is transported to the reaction chamber 106 which has been 
exhausted in the same way. In this reaction chamber 106, a silicon oxide 
film 203 is deposited by a plasma CVD method utilizing TEOS as the main 
material. Deposition condition is shown as the following: 
______________________________________ 
TEOS/O.sub.2 = 10/100 sccm 
RF power 350 W 
Substrate temperature 400.degree. C. 
Deposition pressure 0.25 Torr 
______________________________________ 
In above reaction, a film shown as SiOF.sub.x can be formed by adding 
C.sub.2 F.sub.6. 
This silicon oxide film is deposited by 2000 to 50 .ANG. thickness as a 
base oxide film 203 on a surface on which TFT is to be formed. Rapid 
thermal annealing can be performed by transporting the silicon oxide film 
203 deposited in this reaction chamber 106 to the anneal chamber 104. 
The substrate is transported to the loader 107 again, and then the 
substrate is transported to the reaction chamber 105. Whenever the gate 
valve is opened or closed, the loader and each chamber are always 
exhausted to the same vacuum level (same low pressure level) in every step 
of substrate transportation. 
An amorphous silicon film is deposited by 100 to 1500 .ANG. thickness, 
preferably 300 to 800 .ANG. thickness by a plasma CVD method or LPCVD 
method in the reaction chamber 105. Deposition condition in the plasma CVD 
method is as the following: 
______________________________________ 
SiH.sub.4 = 200 sccm 
RF power 200 W 
Substrate temperature 250.degree. C. 
Deposition pressure 0.1 Torr 
______________________________________ 
This deposition may be performed by LPCVD method (low pressure thermal CVD 
method) utilizing Si.sub.2 H.sub.6, Si.sub.3 H.sub.8. In this case, gas 
phase reaction should be performed with substrate temperature of 
450.degree. C., and reaction pressure of 1 Torr. 
The substrate is transported to the reaction chamber 106 further, and a 
silicon oxide film 212 is deposited by 500 to 1500 .ANG. thickness by a 
plasma CVD method utilizing TEOS as the main material. This film functions 
as a protection film of a silicon film. Deposition condition is shown as 
the following: 
______________________________________ 
TEOS/O.sub.2 = 10/100 sccm 
RF power 300 W 
Substrate temperature 350.degree. C. 
Deposition pressure 0.25 Torr 
______________________________________ 
In this way, the blocking film 202 of aluminum nitride or silicon nitride, 
the silicon oxide film 203, the silicon semiconductor film 204, and the 
protection film 212 can be formed in a series and in multilayers on the 
glass substrate 201, as is shown in FIG. 5(A). As each chamber and the 
loader with the robot arm are partitioned by a gate valve in the system in 
FIG. 4, impurities will not be mixed with one another between each 
chamber. Especially C, N, O in the silicon film can be at least 
5.times.10.sup.18 cm.sup.-3 or less. 
The substrate is taken out of the preliminary chamber 101, and patterning 
is performed to form an island silicon region 204. As is shown in FIG. 
5(B), a silicon oxide film 205 is formed by 200 to 1500 .ANG. thickness, 
preferably 500 to 1000 .ANG. thickness. This silicon oxide film also 
functions as a gate insulating film. Therefore this silicon oxide film 
should be formed very carefully. Here, TEOS is utilized as a material, and 
the film is formed in a deposition apparatus shown in FIG. 1 and FIG. 2 
(i.e. the reaction chamber 106 in FIG. 4). 
In depositing the silicon oxide film, two pairs of electrodes in vertical 
to one another are utilized. Each pair is a pair of electrodes 12 and 13, 
and a pair of electrodes 15 and 16. By applying a constant phase 
difference (usually 90.degree.) and high frequency electric power (50 
MHz), a high frequency electric power of Lissajous waves is provided to 
the chamber. High frequency electric power of 13.56 MHz is supplied 
between a mesh electrode 22 and an earth electrode 25. By supplying 
ultraviolet light from an ultraviolet light source 21 comprising a mercury 
lamp to the substrate 19 (109 in FIG. 4), a silicon oxide film 205 is 
formed. Here, the substrate is heated to approximately 200 to 600.degree. 
C., preferably 300.degree. C. Reaction pressure is 0.01 to 10 Torr, 
preferably 0.1 to 1 Torr. 
In this case, the reaction gas is mixed and activated by high frequency 
electric power of Lissajous' waves, and decomposition is accelerated with 
high efficiency. Deposition with high step coverage can be performed at a 
high rate on a substrate by high frequency electric power provided between 
the mesh electrode 22 and an opposite earth electrode 25, and by 
ultraviolet light from the ultraviolet light source 21. 
In the case of forming a silicon oxide film by utilizing organic silane gas 
like this example 7, C (carbon) is reacted with O (oxygen) by irradiation 
of ultraviolet light, and carbon can be taken outside as CO.sub.2 from the 
silicon oxide film. A silicon oxide film with good quality without C 
(carbon) can be obtained. 
A film of high quality with high step coverage can be obtained by applying 
high frequency electric power of Lissajous' waves, and by irradiation of 
ultraviolet light. In addition, by narrowing the space between the pair of 
electrodes 22 and 25 which applies high frequency electric field to the 
substrate in vertical direction, high deposition speed can be obtained. 
It is effective to perform rapid thermal anneal by irradiation of infrared 
light in N.sub.2 O atmosphere after the silicon oxide film 205 is formed 
and the substrate is loaded to the anneal chamber 104. This is 
particularly effective in decreasing interface state between the silicon 
oxide film 205 and the silicon region 204. 
As is shown in FIG. 5(B), a silicon region 204 is crystallized by 
irradiating KrF excimer laser 213 (wavelength 248 nm or 308 nm, pulse 
width 20 nsec). Energy density of laser is 200 to 400 mJ/cm.sup.2, 
preferably 250 to 300 mJ/cm.sup.2. During irradiation of laser, the 
substrate is heated at 300 to 500.degree. C. According to study by RAMAN 
spectrum for crystal character of the silicon film 204 formed in this way, 
relatively broad peak is observed at approximately 515 cm.sup.-1, 
different from that of single-crystal silicon (521 cm.sup.-1). It is found 
that the silicon film 204 has become crystal semiconductor, for example, 
polycrystal semiconductor. After that, the silicon film 204 is annealed at 
350.degree. C. in hydrogen for two hours. The process of this 
crystallization can be performed by heating. 
After that, an aluminum film of 2000 .ANG. to 1 .mu.m is formed by electron 
beam deposition method. This is patterned, and a gate electrode 206 is 
formed. Scandium (Sc) can be doped in aluminum by 0.15 to 0.2% by weight. 
Nextly, the substrate is dipped in ethylene glycol solution of pH=7 
containing tartaric acid of 1 to 3%. Anodic oxidation is performed with 
platinum as a cathode and this gate electrode of aluminum as an anode. In 
anodic oxidation, voltage is increased to 220V at first with constant 
current, and is kept for an hour, and is finished. In this embodiment, 
under condition of constant current, it is appropriate increase speed of 
voltage is 2-5V/minute. In this way, anodic oxide 209 of 1500 to 3500 
.ANG. thickness, for example, 2000 .ANG. thickness is formed. (FIG. 5(C)) 
After that, by ion doping method (also referred to as plasma doping 
method), an impurity (phosphorus) is implanted in self-align way to an 
island silicon film of each TFT, with utilizing the gate electrode portion 
as a mask. As doping gas, phosphine (PH.sub.3) is utilized. Dose amount is 
1 to 4.times.10.sup.15 cm.sup.-2. 
As is shown in FIG. 5(D), by irradiating KrF excimer laser 216 (wavelength 
248 nm or 308 nm, pulse width 20 nsec), crystal character of the portion 
of which crystal character has been degraded by above mentioned implant of 
impurity is improved. Energy density of laser is 150 to 400 mJ/cm.sup.2, 
preferably 200 to 250 mJ/cm.sup.2. In this way, N type impurity 
(phosphorus) regions 208 and 209 are formed. Seat resistance of these 
regions is 200 to 800 .OMEGA./cm.sup.2. In this process, what is called 
RTP (rapid thermal process) can be also utilized. In RTP, the sample is 
heated not by utilizing laser but by utilizing flash lamp to heat the 
sample at 1000 to 1200.degree. C. (the temperature of silicon monitor) in 
a short time. 
After that, an interlayer insulator 210 comprising silicon oxide is formed 
on the whole surface by utilizing a chamber 104 of the apparatus in FIG. 4 
to a thickness of 0.3 .mu.m to 1 .mu.m, e.g. 3000 .ANG. (0.3 .mu.m), by a 
plasma CVD method utilizing TEOS as a material and oxygen, a low pressure 
CVD method, or a normal pressure CVD method with ozone. The substrate 
temperature is 250 to 450.degree. C., e.g. 350.degree. C. After 
deposition, to obtain flatness on the surface, this silicon oxide film is 
mechanically polished. In this process, isotropic dry etching can be 
performed by utilizing the reaction chamber provided in the apparatus in 
FIG. 4. Furthermore, an ITO film is deposited by sputter method, and a 
pixel electrode 211 is formed by patterning this. (FIG. 5(E)) 
In this way, a thin film integrated circuit can be formed on one side of 
the substrates of the electro-optical device in FIG. 5. Of course, 
peripheral circuits can be formed on the same substrate simultaneously 
with the circuit shown in this figure. By etching the interlayer insulator 
210, a contact hole is formed in source/drain of TFT as is shown in FIG. 
5(E). Wirings 212 and 213 of chromium or titanium nitride are formed, and 
the wiring 213 is connected to the pixel electrode 211. Here, the contact 
hole can be formed protruding the source/drain region (island silicon). In 
this case, the area of the contact hole protruding the island silicon 
accounts for 30 to 70% of the contact hole. In this case, a contact is 
formed not only on the upper surface of the source/drain but also on the 
side surface of the source/drain. Hereinafter a contact like this is 
called as a top side contact. In the conventional structure, to form a top 
side contact, a silicon oxide film of the base other than the island 
silicon, and the substrate further were etched during an etching step of 
the interlayer insulator. In this embodiment, the aluminum nitride film or 
silicon nitride film 202 functions as an etching stopper, and etching is 
stopped there. 
In usual cases, it was imperative that the size of the contact hole should 
be smaller than source/drain. On the contrary, in the top side contact, 
the size of an island can be smaller than that of the contact hole. As a 
result, it was possible to make the island very small. On the contrary, 
because the contact hole can be made bigger, mass production and 
reliability can be improved. 
Hydrogenation of silicon is completed by annealing at 300 to 400.degree. C. 
for 0.1 to 2 hours in hydrogen. In this way, a thin film integrated 
circuit having TFT is completed. Many sets of TFT formed simultaneously 
are arranged in matrix, and a monolithic type active matrix liquid crystal 
display device having peripheral circuits on the same substrates is 
formed. 
As described in the foregoing, the present invention comprises arranging 
two pairs of parallel planar type electrodes in such a manner that an 
electric field can be applied in parallel with the substrate. More 
specifically, one pair is set in such a manner that it may cross the other 
pair making right angle with respect to the other pair, and placing the 
substrate on one of the third pair of parallel planar type electrodes 
installed with a small distance taken therebetween. A high frequency power 
having a Lissajous's waveform is applied from the crossing two pairs of 
electrodes while irradiating ultraviolet light to the substrate. In this 
manner, a film having a superior quality and a high step coverage can be 
deposited at a high deposition rate. 
Although the mercury lamp is used in the foregoing, other means for 
irradiating an ultraviolet light to the substrate can be used instead. 
While the invention has been described in detail and with reference to 
specific embodiments thereof, it will be apparent to one skilled in the 
art that various changes and modifications can be made therein without 
departing from the spirit and scope thereof.