JPH0881778A - Method for continuously forming film by radical cvd under high pressure and device therefor - Google Patents

Abstract

PURPOSE: To deposit the formed radical of a film forming element on a substrate and to obtain a thin film excellent in electrical and optical characteristics by forming a thin laminar flow of a reacting gas close to the substrate surface and joining a high-density neutral radical gas to the laminar flow to decompose the reacting gas. CONSTITUTION: A partition plate 4 is provided in the gas passage 1 of a continuous film forming device at a minute distance from the surface 2 of a substrate. A reacting gas passage 5 is formed by partition plate 2 and the substrate surface 2, and a radical gas passage 6 is formed by the partition plate 4 and the wall surface on the other side. A laminar flow of the reacting gas is formed along the substrate surface 2 and joined to a radical gas current contg. the high- density neutral plasma formed in the high-pressure plasma at a confluence 7. The reacting gas is decomposed by the neutral radical diffused into the reacting gas, and the generated film forming element is deposited on the substrate surface 2 to continuously form a thin film. Consequently, a thin film with the internal defect and surface ruggedness reduced and excellent in electrical and optical characteristics is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous film forming method by a radical CVD method under high pressure and an apparatus therefor, and more particularly, there is no damage to a substrate due to charged particles or thermal damage due to heating of the substrate. The present invention relates to a continuous film forming method and an apparatus for forming a thin film having few defects and unevenness on the surface and excellent electrical and optical characteristics.

[0002]

2. Description of the Related Art Conventionally, techniques for forming a thin film on a substrate are roughly classified into physical methods (Physical vapor deposition).
: PVD and chemical vapor deposition
: CVD), but in the field of electronic engineering, the plasma CVD method, which is a chemical method, is particularly drawing attention. In the plasma CVD method, it is possible to freely control the temperature of the substrate to generate neutral radicals and ions that are reactive species in plasma, and to use the high energy state of plasma, so that it can be applied to reactions that are usually difficult. There are advantages. As a means for exciting and maintaining the plasma, a DC electric field, a commercial frequency of 50/60 Hz, and R. F. Electric fields, microwaves, millimeter waves, light, etc. are used. Present plasma CVD is generally performed under a low pressure of 1 Torr or less. In particular, recently, ECR (electron cycro
tron resonance) in high vacuum using plasma (10 ^-3 ~
Plasma CVD at 10 ⁻⁵ Torr) is performed.

However, in such a low-pressure plasma state, a plasma called nonequilibrium plasma having only an extremely high electron temperature can be generated, but ions generated in the plasma,
It is considered that the energy of electrons also becomes high and the electrons directly collide with the substrate with high kinetic energy. Further, there is a problem that the film forming speed is slow because of the low pressure.

Further, in the conventional plasma CVD, for example, 1000 to 1200 in the thermal CVD which is generally adopted for producing a polycrystalline silicon (Si) thin film.
Heating at ℃ is required, and when exposed to such high temperatures, mutual diffusion of the elements that make up the substrate and thin film occurs, and if the elements that make up the substrate and thin film differ, the substrate contains trace elements. In this case, there is a problem that impurities are introduced into the thin film. Further, in order to produce a polycrystalline silicon thin film by a relatively low temperature treatment, an amorphous silicon thin film was first produced, and then the substrate was heat-treated at 600 to 700 ° C. to promote its crystallization.

As described above, conventionally, in order to control the crystal structure of the thin film formed on the substrate, it was necessary to heat the substrate to at least about 600 ° C. or higher. Therefore, not only a low melting point material cannot be used as the substrate, but also the substrate may be thermally damaged. In addition, a high electric field is required to directly excite the reaction gas into a plasma state, and the resulting charged particles have high kinetic energy, and these are incident on the substrate to cause defects in the thin film or the substrate. I also have problems.

[0006] Therefore, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 4-3370.
As disclosed in Japanese Patent Laid-Open No. 76-76, plasma of a carrier gas composed of an inert gas, which is easy to generate and maintain under high pressure of several Torr to several atmospheres, is generated, whereby reactive gas molecules are generated in a gas phase or on a substrate. By decomposing and activating above to generate high density neutral radicals and growing a thin film on the substrate, high-speed film formation is possible, and thermal damage does not occur in many materials. We have already provided a high-speed film formation method by plasma and radical CVD that enables polycrystallization or crystallization of a thin film only by heating the substrate to the temperature. In other words, this film formation method transports neutral radicals and hydrogen atom radicals of an inert gas generated in plasma to the film formation part outside the plasma by the flow of the radical generation gas, and reacts with a film formation element. By mixing with the gas, the reaction gas is decomposed in the gas phase and a target thin film is formed at high speed on the low temperature substrate.

[0007]

However, if the gas flow is disturbed, the radical species generated by the decomposition of the reaction gas aggregate in the gas phase to form clusters or powders. When such clusters and powders are deposited on the substrate, many defects are introduced inside the thin film, and the surface shape becomes rough, resulting in poor electrical and optical characteristics of the formed thin film. .

In view of the above situation, the present invention is to solve the problem by adopting the film forming method described in the above publication for the basic technical idea of separating the plasma region and the film forming region. At the same time, it is possible to suppress the radical species generated by the decomposition of the reaction gas from aggregating in the gas phase, and to have excellent electrical and optical characteristics of the thin film and to form a film at high speed under high pressure. Provided are a continuous film forming method by a radical CVD method and an apparatus thereof.

[0009]

In order to solve the above-mentioned problems, the present invention supplies a reaction gas containing a film-forming element only to the surface of a substrate, and has a uniform thickness and density near the surface of the substrate. Forming a thin reaction gas laminar flow of several Torr ~
A radical gas containing high-density neutral radicals generated in high-pressure plasma of several atmospheres is supplied to the upper layer of the reaction gas laminar flow without disturbing the flow, and reacted by the neutral radicals diffused in the reaction gas. Provided is a continuous film formation method by a radical CVD method under high pressure, which is formed by decomposing gas and depositing a film forming element on a substrate surface to continuously form a thin film.

In this case, it is a more preferred embodiment that the reaction gas laminar flow and the radical gas flow are merged in parallel or at an acute angle, and that the reaction gas is diluted with an inert gas and supplied. . Furthermore, it is practical to move the substrate relatively in the forward or reverse direction with respect to the flow direction of the reaction gas.

Further, in the continuous film forming apparatus, at least one side wall surface of the gas flow path is formed on the substrate surface, and
A gas is formed in the gas flow path with a minute gap from the substrate surface, and a reaction gas flow path is formed between the partition plate and the substrate surface, and the partition plate faces the substrate surface. A radical gas flow channel is formed with the other side wall surface of the flow channel or between a pair of partition plates, and the downstream end of the partition plate serves as a confluence of the reaction gas flow channel and the radical gas flow channel, and the reaction gas flow is formed. A supply means for supplying a reaction gas containing a film-forming element is provided on the upstream side of the channel, while a high frequency high electric field region for generating high pressure plasma of several Torr to several atmospheres is formed on the upstream side of the radical gas channel, and the region is formed. Is provided with a means for supplying a radical-producing gas such as an inert gas, and a high-pressure reaction gas and a radical-producing gas are respectively supplied from the gas supply means to form a laminar flow of the reaction gas along the substrate surface, High density produced in high pressure plasma A radical gas flow containing neutral radicals is merged into the reaction gas laminar flow at the confluence portion, the reaction gas is decomposed by the neutral radicals diffused in the reaction gas, and the film-forming element is deposited on the substrate surface to form a thin film. A continuous film forming apparatus by a radical CVD method under high pressure is formed by continuously forming

Here, the partition plate is a parallel plate and is arranged parallel to the substrate surface, or one surface of the partition plate is arranged parallel to the substrate surface and the other surface is Being an inclined surface having an acute angle with respect to the substrate surface, and the partition plate also serves as an electrode for plasma generation,
Further, it is a preferred embodiment that the substrate is moved in parallel with respect to the gas flow path in the forward direction or the reverse direction relative to the flow direction.

[0013]

The continuous film formation method and apparatus using the radical CVD method under high pressure according to the present invention having the above-mentioned contents are as follows:
The plasma generation region, that is, the radical generation region and the film formation region are separated, and the reaction gas (raw material gas) containing the film forming element is supplied only to the substrate surface, and the thickness and density are uniform and thick near the substrate surface. In the state in which a thin laminar flow of the reaction gas is formed, a radical gas containing high-density neutral radicals generated in high-pressure plasma of several Torr to several atmospheres generated in the plasma generation region The reaction gas is merged in parallel or at an acute angle so as not to disturb the flow of the reaction gas in the upper layer of the laminar flow, and the reaction gas is decomposed by the neutral radicals in the radical gas, and the resulting radical species of the film-forming element are generated on the substrate surface. It is deposited on and formed into a film. In this case, by relatively moving the substrate in the forward direction or the reverse direction with respect to the flow direction of the reaction gas, it is possible to form a large area or continuously.

Here, it is important to dilute the reaction gas with an inert gas and supply it to the surface of the substrate. The diluting action will be described below. The mean free path of gas molecules at atmospheric pressure is several 100n
Therefore, when the concentration of the reaction gas is high, the radical species generated by their decomposition are aggregated in the gas phase to form clusters or powders. When such clusters and powders are deposited on the substrate, many defects are surrounded inside the thin film, and the surface shape becomes rough, and as a result, only a film with poor electrical and optical characteristics can be obtained. . Therefore, by preliminarily diluting the reaction gas with an inert gas and making the mean free path of the reaction gas sufficiently long, it becomes possible to suppress the agglomeration of radical species in the gas phase. When the concentration of the reaction gas is high, the number of reaction gas molecules is larger than the number of neutral radicals transported from the plasma generation region, and as a result, only part of the supplied reaction gas is decomposed. The use efficiency of expensive reaction gas becomes low. Therefore, it is possible to improve the utilization efficiency of the reaction gas by previously diluting the reaction gas with the inert gas.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in the accompanying drawings. FIG. 1 is a conceptual diagram showing the film forming principle of the present invention. In the figure, 1 is a gas channel, 2 is a substrate surface, 3 is a wall surface of the gas channel 1, 4 is a partition plate, 5 is a reaction gas channel, Reference numerals 6 respectively denote radical gas passages.

The term "reaction gas" as used herein means a raw material gas containing a film-forming element, and a mixture of an inert gas and the like is also generically called a reaction gas. The "radical gas" is a gas containing neutral radicals generated by decomposing or exciting a radical-producing gas such as an inert gas in plasma. For example, when forming a silicon thin film on a substrate, silane gas (Si
H _4: raw material gas) and a mixed gas of He, using a mixed gas of He and H ₂ as the radical generating gas. In this case, the radical gas is a mixed state of excited He atom radicals, hydrogen atom radicals (including the ground state of hydrogen atoms), and neutral particles (He atoms not excited, hydrogen molecules).

In the continuous film forming method by the radical CVD method under high pressure of the present invention, the reaction gas containing the film-forming element is supplied only to the substrate surface, and the thickness and density are uniform and thick near the substrate surface. While forming a thin laminar flow of the reaction gas,
A radical gas containing high-density neutral radicals generated in high-pressure plasma of several Torr to several atmospheres is supplied to the upper layer of the reaction gas laminar flow without disturbing the neutral gas and diffused into the reaction gas. The gist is to decompose a reaction gas by radicals and deposit a film-forming element on the substrate surface to continuously form a thin film.

Further, in the first embodiment of the continuous film forming apparatus of the present invention, as shown in FIG. 1 (a), a parallel and flat gas flow path 1 is formed by a substrate surface 2 and a wall surface 3 facing it. At the same time, a partition plate 4 is disposed in the gas flow path 1 at a minute distance from the substrate surface 2, and the partition plate 4 and the substrate surface 2 form a reaction gas flow path 5 and the partition wall. Plate 4 and substrate surface 2
A radical gas flow channel 6 is formed by the other side wall surface 3 of the gas flow channel 1 facing the above, and the downstream end of the partition plate 4 is not formed as a reaction gas flow channel 5 and a merging portion 7 of the radical gas flow channel 6. A reaction gas supply means 8 containing a film-forming element is provided on the upstream side of the reaction gas flow channel 5, while several Torr to the upstream side of the radical gas flow channel 6.
A high-frequency high-electric field region (not shown) for generating high-pressure plasma of several atmospheres is formed, and a supply means 9 for supplying a radical-producing gas such as an inert gas is provided in the region, and a high-pressure reaction gas and radicals are provided. The generated gas is supplied to the gas supply means 8,
9 to form a laminar flow of the reaction gas along the substrate surface 2, and a radical gas flow containing high-density neutral radicals generated in the high-pressure plasma at the confluence section 7 to form the reaction gas laminar flow. It is characterized in that the reaction gas is decomposed by the neutral radicals diffused in the reaction gas and the film forming element is deposited on the substrate surface 2 to continuously form a thin film.

Here, in the present invention, it is important to form a thin laminar flow of the reaction gas near the substrate surface 2 and to form a radical gas flow in the upper layer so as not to disturb the flow of the reaction gas. In this embodiment, the parallel flat gas flow path 1
The width D ₁ is set to 100μm, the thickness D ₂ of the partition plate 4 is 10 to 20 [mu] m, the width D ₃ of the reaction gas channel 5 is set to 10 to 20 [mu] m.

Then, the radical producing gas of several Torr to several atmospheres is supplied from the radical producing gas supply means 9 at 10 MHz to
A high-pressure plasma is generated by supplying a high-frequency high electric field of 100 GHz to the plasma generation region, and the radical gas generated in the plasma is supplied to the radical gas flow path 6 along with the gas flow, and the reaction gas flow path 5 The reaction gas flow supplied to the above is mixed in parallel at the merging portion 7, and the reaction gas is decomposed and deposited on the substrate surface 2 in the film forming region on the downstream side of the merging portion 7.

In the second embodiment of the continuous film forming apparatus of the present invention, as shown in FIG. 1 (b), a gas flow path 1 is formed by a pair of substrate surfaces 2 and 2 arranged in parallel. 2 is provided with a partition plate 4 at a minute interval, and the partition plate 4 and the substrate surface 2
To form a reaction gas flow path 5 and a radical gas flow path 6 between the partition plates 4 and 4. The reaction gas is supplied from the supply means 8 to each reaction gas flow path 5 and the radical gas flow path 5 is formed. The radical generating gas is passed from the supply means 9 to the gas flow path 6 through the plasma generation region, the generated radical gas is supplied, and is merged at the merging portion 7 at the downstream end of each partition plate 4, and the gas is flown on the downstream side thereof. Similarly, a thin film is formed on the surface 2 of each substrate.

In the third embodiment of the continuous film forming apparatus of the present invention, as shown in FIG. 1 (c), the gas flow path 1 is formed by the substrate surface 2 and the parallel surface 3a of the wall surface 3 facing it. In the gas flow channel 1, the reaction gas flow channel 5 is formed by arranging the flat surface portion 4a of the partition plate 4 at a minute distance from the substrate surface 2 to form an acute angle with respect to the flat surface portion 4a. A radical gas channel 6 is formed by the set inclined portion 4b of the partition plate 4 and the inclined surface 3b formed on the wall surface 3 in parallel with the inclined portion 4b. Here, the downstream end portion of the partition plate 4 is a knife edge having an acute angle, the width D _{4 of the} leading end portion is set to 10 to 20 μm, and the downstream end portion is the confluence portion 7. There is. Therefore, the substrate surface 2 which is supplied to the reaction gas channel 5 is
The thin laminar flow of the reaction gas formed in the vicinity of and the radical gas flow supplied to the radical gas flow path 6 merge at an acute angle at the merging portion 7, and the thin film is formed on each substrate surface 2 on the downstream side in the same manner as described above. Is formed.

In the above-described embodiment, the substrate S is moved in parallel in the forward or reverse direction with respect to the flow direction of the reaction gas along the gas flow path 1 to continuously form a large area. It becomes possible to do. In this case, the substrate S
May be a rigid plate such as a rigid glass plate, metal plate or synthetic resin plate, or a flexible film such as a flexible polymer film or metal film.
A rigid plate is moved in parallel over its effective area, and a flexible film is wound around a pair of drums and continuously fed to a film forming region to continuously form a film.

Next, a specific film forming apparatus based on the first embodiment shown in FIGS. 2 to 4 will be described. What is shown is an experimental apparatus for demonstrating the film formation principle according to the present invention, and the substrate S is fixed for film formation, but the present invention is not limited to the illustrated embodiment.

The present film-forming apparatus is provided with a quartz glass tube 10 installed upright.
The upper and lower ends are closed by the upper flange plate 11 and the lower flange plate 12, the cylindrical conductor 13 is fixed to the upper surface of the lower flange plate 12, and the insulator 14 is interposed at the center of the conductor 13. The cylindrical center electrode body 15 is fixed, and the tip of the center electrode body 15 is exposed to the center hole 17 of the electrode plate 16 fixed to the upper end of the conductor 13. Further, a film forming portion 18 having a vertical gap penetrating in the vertical direction is attached to the upper surface of the electrode plate 16, and a substrate S is attached to one side surface in the gap of the film forming portion 18 so that the remaining space is filled with gas. Without channel 1
The lower end of the gas flow path 1 faces the central hole 17.
In addition, the spacer 1 arranged near the lower end with respect to the substrate surface 2
A partition plate 4 is fixed via 9 and a reaction gas flow path 5 formed between the substrate surface 2 and the partition plate 4 is penetrated through the film forming section 18 and the substrate S to serve as a reaction gas supply means 8. The reaction gas supply pipe 20 is connected. Further, a radical producing gas supply pipe 21 as a radical producing gas supply means 9 penetrating through the lower flange plate 12 is connected to the space formed between the conductor 13 and the center electrode body 15.

Then, a high frequency high voltage is applied to the center electrode body 15, while the electrode plate 16 and the conductor 13 are grounded, and the lower flange plate 12 is preferably made of a conductive material. The lower flange plate 12 is grounded while the conductor 13 and the electrode plate 16 are electrically connected to each other, and a high frequency high voltage region is formed between the tip of the center electrode body 15 and the center hole 17 of the electrode plate 16. Therefore, when a radical-producing gas of about 1 atm is supplied from the radical-producing gas supply pipe 21 to the space between the conductor 13 and the center electrode body 15,
High-pressure plasma based on the radical-producing gas is generated in the high-frequency and high-voltage region, and the neutral radicals and the like generated in the plasma-generating region P are supplied to the radical gas passage 6 through the central hole 17. On the other hand, the reaction gas supplied from the reaction gas supply pipe 20 passes through the reaction gas channel 5 between the substrate surface 2 and the partition plate 4 and becomes a thin laminar flow along the substrate surface 2. Here, the pressure of the reaction gas is set to be equal to or slightly higher than the pressure of the radical-producing gas. An exhaust pipe 22 is connected to the upper flange plate 11 and an exhaust means such as a rotary pump (not shown) is connected to exhaust the inside of the quartz glass pipe 10.

Further, the electric conductor 1 is generated by the generation of plasma.
3, since the electrode plate 16 and the central electrode body 15 are heated,
A cooling pipe 23 for cooling the conductor 13 and the center electrode body 15 with water is provided inside. Further, in order to confirm the generation state of the high-pressure plasma, a viewing window 24 penetrating the inside and outside of the conductor 13 and a viewing window 25 that is the upper flange plate 11 and immediately above the gas flow path 1 of the film forming unit 18 are provided. ing.

FIG. 5 shows a main part of a concrete film forming apparatus based on the third embodiment. This film forming apparatus is basically shown in FIG.
4 is similar to the film forming apparatus according to the first embodiment shown in FIG. 4, but the structure of the film forming unit 18 is different. That is,
In the film forming unit 18 of the present film forming apparatus, the substrate S is attached to one side surface in the gap, the remaining space is used as the gas flow path 1, and the flat surface 4a of the partition plate 4 having a substantially triangular cross section is formed on the substrate surface 2. With respect to the flat portion 4a, the reaction gas passage 5 is formed with a minute gap therebetween, and the inclined portion 4b of the partition plate 4 is set at an acute angle with respect to the flat portion 4a.
The radical gas channel 6 is formed by the inclined surface 3b formed by notching the other side wall surface 3 of the gas channel 1 so as to be parallel to the inclined portion 4b.

Next, a gas supply system and an exhaust system in the film forming apparatus of the present invention will be briefly described with reference to FIG.
The gas supply system is composed of the reaction gas supply means 8 and the radical generation gas supply means 9 and the purge gas supply means 26 such as nitrogen gas, and the gas exhaust system is at or below atmospheric pressure. The exhaust means 27 has a function of exhausting gas and treating dangerous raw material gas. In the present embodiment, the reaction gas supply means 8 includes a silane gas cylinder 28, a filter 29, a diaphragm type adjusting valve 30, an opening / closing valve 31, a filter 32, a flow meter 33, a needle valve 34 and a check valve 35 connected in series. Is connected to the reaction gas supply pipe 20 and is also connected to the reaction gas supply pipe 20 from the helium gas cylinder 36 via the diaphragm type regulating valve 37 and the flow meter 38 to adjust the flow rates of the silane gas and the helium gas to set the mixing ratio. Then, it can be supplied to the reaction gas channel 5. Further, the radical generating gas supply means 9
In the present embodiment, is connected to the radical-producing gas supply pipe 21 from the helium gas cylinder 39 through the filter 40, the diaphragm type regulating valve 41 and the opening / closing valve 42,
From the hydrogen gas cylinder 43 to the diaphragm type adjustment valve 44, the check valve 45, the flow meter 46, the needle valve 47 and the opening / closing valve 48.
It is possible to connect to the radical generation gas supply pipe 21 via the, to adjust the flow rates of the helium gas and the hydrogen gas, set the mixing ratio, and supply the radical gas flow path 6.

The purging gas supply means 26 is connected between the nitrogen gas cylinder 49 and the silane gas cylinder 28 and the filter 29 through the diaphragm type regulating valve 50, the check valve 51 and the opening / closing valve 52, and is usually The on-off valve 53 is closed, and the air (oxygen) in the pipe is replaced with nitrogen before using the silane gas, and the on-off valve 53 is opened when the silane gas in the pipe is replaced with nitrogen after using the silane gas. To use.

Further, the exhaust means 27 branches the pipe connected to the exhaust pipe 22, connects one to the rotary pump 54 via the open / close valve 53, and further connects to the silane gas removing device 56 via the open / close valve 55. Then, the other side is connected to the flow meter 59 via the filter 57 and the opening / closing valve 58, and further connected to the exclusion device 56 via the opening / closing valve 60 for exhausting. Here, when film formation is performed by setting the pressure in the film forming apparatus, that is, the pressure in the quartz glass tube 10 to atmospheric pressure or less, the opening / closing valves 58 and 60 are closed, and the opening / closing valves 53 and 55.
On the contrary, when the rotary pump 54 is forcibly evacuated and the film formation is carried out at the atmospheric pressure or higher, the open / close valves 53, 5 are reversed.
5 is closed and the on-off valves 58 and 60 are opened to allow natural exhaust. Further, the exhaust pipe 22 is also connected to the reaction gas supply pipe 20 via an on-off valve 61 which is normally closed so that the inside of the silane gas pipe can be exhausted by opening the on-off valve 61.

In the present embodiment, a mixed gas of silane gas and helium gas is used as the reaction gas, but the reaction gas supply pipe 20 is provided with an opening / closing valve 62 so that hydrogen gas can be mixed and used. It is connected between a needle valve 47 connected to the hydrogen gas cylinder 43 and an opening / closing valve 48. By piping in this way, it is possible to use a mixed gas of silane gas, helium gas, and hydrogen gas as a reaction gas when the opening / closing valve 62 is opened.

The rotary pump 54 is connected between a diaphragm type regulating valve 30 connected to the silane gas cylinder 28 via an opening / closing valve 63 and an opening / closing valve 31,
By opening the on-off valve 63, the silane gas can be exhausted and the gas in the rotary pump 54 can be replaced with nitrogen gas.

Next, a case where a silicon thin film is actually formed on the substrate surface 2 by the film forming apparatus according to the first embodiment will be described. First, the flow state of the reaction gas channel 5 and the radical gas channel 6 at the confluence 7 is examined by computer simulation, and the thickness of the partition plate 4 and the widths of the reaction gas channel 5 and the radical gas channel 6 are optimized. I went. In FIG. 7, the partition plate 4 has a thickness of 50 μm and the reaction gas channel 5 has a width of 20 μm.
m and the width of the radical gas channel 6 is 100 μm, the flow of the radical gas is shown. In this case, it is found that a large vortex flow is generated at the confluence portion 7, and it is speculated that the radical gas flow disturbs the laminar flow of the reaction gas. On the other hand, FIG.
Shows the flow of the radical gas when the partition plate 4 has a thickness of 20 μm, the reaction gas flow channel 5 has a width of 20 μm, and the radical gas flow channel 6 has a width of 100 μm. In this case, no swirl is generated at the confluence portion 7. I knew that. However, even if the partition plate 4 has a thickness of 20 μm, it can be presumed that if the intervals of the streamlines are made finer, a small vortex flow is generated, but the laminar flow of the reaction gas is not disturbed. In fact, it was found that when the thickness of the partition plate 4 was 50 μm, when the thickness was 20 μm, the film formation rate was faster and the surface irregularities were smaller than when the thin film was obtained. Therefore, in this embodiment, the partition plate 4 has a thickness of 20 μm.
And the following film formation was performed.

Further, prior to the actual film formation, atmospheric pressure plasma was generated using a radical-producing gas composed of a mixed gas of helium and hydrogen, and the mixing ratio was changed to examine the amount of silane decomposed. The amount of silane decomposed was examined by measuring the amount of silicon deposited (μm) on the substrate surface. FIG. 9 shows the results, showing that the amount of silane decomposition increases when the hydrogen concentration is about 70% or more, and it is effective to use a radical-forming gas in which helium and hydrogen are mixed for the decomposition of silane. It was confirmed. In addition, an inert gas such as helium is essential for facilitating the generation of plasma and stabilizing its maintenance, and also for generating neutral radicals with a relatively long lifetime in a metastable state. Is preferably set to 10 to 30%.

Then, a reaction gas mainly composed of silane gas containing silicon as a film forming element is caused to flow near the substrate surface, and a radical generation gas in which helium and hydrogen are mixed is passed through a plasma generation region to generate a radical gas. A thin silicon film was formed by flowing the reaction gas in parallel with the upper layer. Regardless of the film forming conditions, a silicon thin film firmly attached to the substrate was obtained downstream from the confluence of the reaction gas and the radical gas. The film forming conditions in this case are shown in the following table.

[0037]

By this film formation, it was found that when pure silane (not diluted with helium) was used as a reaction gas, the utilization efficiency of silane was several percent or less. The maximum film formation rate was about 5 nm / s.

On the other hand, when a mixed gas of silane diluted to 10% with helium (helium: 90%, silane: 10%) was used as the reaction gas, about 70% of the supplied silane was used.
Decomposed and contributed to film formation. The maximum film formation rate in this case was about 7 nm / s. In addition, silane is used as helium for 2.
When a mixed gas diluted to 5% (helium: 97.5%, silane: 2.5%) was used, almost all of the supplied silane was decomposed and contributed to film formation. The maximum film formation rate in this case was about 2 nm / s. These results are shown in FIG.
The horizontal axis of this graph is the distance from the silane gas merging portion, and the vertical axis is the film formation rate.

From the above, it was found that by diluting the silane gas with helium, the utilization efficiency of silane can be greatly increased and the maximum film formation rate can be improved.
Further, it has been found that the film formation rate can be controlled according to the distance from the silane gas joining portion, and that if the concentration of the silane gas is lowered, a film having a substantially uniform thickness can be formed to a distance relatively far from the joining portion. In practice, dilute with helium to increase the concentration of silane from 2 to
If it is set within the range of 20%, the film can be formed efficiently. Generally, it can be said that it is effective to dilute a raw material gas containing a film-forming element with an inert gas as a reaction gas.

Next, various modifications of the continuous film forming apparatus based on the technical idea of the present invention will be briefly described. Figure 11
Shows an apparatus for continuously forming a thin film on the surface of a long flexible film F, and the relationship between the conductor 13 and the center electrode body 15 is the same as the apparatus shown in FIG. 16 and the film forming portion 18 are modified to form a gas flow path 1 similar to that of the third embodiment shown in FIG. 1C, and a flexible film F feeding mechanism is further added. In this case, the upper surface 64 of the conductor 13 is formed in the same plane, and the parallel plate-shaped electrode plate 16a and the parallel plate-shaped electrode plate 16b thicker than the electrode plate 16a are provided on the upper surface 64 with respect to each other. The edges are fixed to face each other. The upper surface of one electrode plate 16a corresponds to the parallel surface 3a of the wall surface 3, and the acute knife-edge-shaped inclined surface formed by notching in the upper surface of the edge corresponds to the inclined surface 3b. The upper surface of the other electrode plate 16b corresponds to the flat surface portion 4a of the partition plate 4, and the sharp knife-edge-shaped slope formed by cutting out the lower surface of the edge corresponds to the inclined portion 4b. A guide member 65 is arranged in parallel with each of the electrode plates 16a and 16b at a predetermined interval, and the lower surface of the guide member 65 is a flat sliding surface 66. Therefore, a pair of drums 67 and 68 are arranged on both sides of the guide member 65, and
The middle part of the flexible film F wound around 7, 68 is brought into close contact with the sliding surface 66 of the guide member 65.

Here, the flexible film F and the electrode plate 16b
Has a minute gap between the flat surface portion 4a and the flat surface portion 4a, which serves as the reaction gas flow path 5, and the inclined surface 3 of the electrode plate 16a.
The gap between b and the inclined portion 4b of the electrode plate 16b serves as the radical gas flow channel 6, and the lower opening of the radical gas flow channel 6 faces the tip of the center electrode body 15. in this case,
The reaction gas is supplied between the flexible film F and the electrode plate 16b, and the radical gas is supplied through the gap between the electrode plates 16a and 16b, and the flexible film F is reacted from one drum 67 to the other drum 68. The thin film is continuously formed on the lower surface by feeding the gas in the same forward direction as the gas flow direction. Further, by rotating the drums 67 and 68 in the reverse direction, the flexible film F can be moved in the direction opposite to the flow direction of the reaction gas. Since other configurations are the same as those described above, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 12 shows two flexible films F at the same time.
1A and 1B show the main parts of an apparatus capable of continuously forming a thin film on the surface of F2.
It corresponds to the second embodiment shown in FIG. This film forming apparatus has a pair of antisymmetric guide members 69 and 70 facing each other, and has parallel sliding surfaces 69a and 70a and slanted sliding surfaces that taper to the end side. 69b, 70
The gas flow path 1 is formed by b and each slanted sliding surface 69b,
70b is a partition plate 71 that also functions as an electrode at a predetermined interval.
72 is arranged, and the intermediate portions of the flexible films F1 and F2 wound around the drums 67 and 68 are closely contacted along the sliding surfaces of the guide members 69 and 70. Then, when a high frequency high voltage is applied to both partition plates 71, 72, a high frequency high electric field region (plasma generation region P) is formed between the tips whose intervals are narrowed. Since other configurations are the same as those described above, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 13 shows an essential part of an apparatus capable of continuously forming a thin film on the surfaces of two rigid substrates S1 and S2 at the same time. The basic structure of the film forming apparatus is shown in FIG.
This corresponds to the third embodiment shown in (c). This film forming apparatus has a main electrode body 73 having a tapered cross-section at the tip and other parallel plane portions, and a predetermined interval at the tip of the main electrode body 73 and a predetermined distance from each other. A pair of sub-electrode bodies 74, 75 arranged apart from each other constitutes an electrode portion, and each of the tapered slopes 73a, 7 of the main electrode body 73 is formed.
3b, the inclined surface 74a at the tip of the sub-electrode body 74, and the sub-electrode body 7
5, the inclined surface 75a at the tip of the electrode 5 is set to be substantially parallel, and the substrate S1 is arranged in parallel with the one side flat surface portion of the main electrode body 73 and the flat surface portion of the sub electrode body 74 at a predetermined interval. The substrate S2 is arranged in parallel to the other flat surface portion of the body 73 and the flat surface portion of the sub-electrode body 75 at a predetermined interval. Here, the reaction gas flow path 5 is formed between the sub-electrode bodies 74 and 75 and the substrates S1 and S2, and the slopes 73 of the main electrode body 73 are formed.
a, 73b and slopes 74a, 75 of the sub-electrode bodies 74, 75
A radical gas flow path 6 is provided between a. Then, a high frequency high voltage is applied to the main electrode body 73, and the sub electrode bodies 74 and 75 are
Is grounded, and the plasma generation region P is formed at the tip of the main electrode body 73.
Is formed. Further, the substrates S1 and S2 can be relatively moved in parallel to the electrode body. Since other configurations are the same as those described above, the same components are designated by the same reference numerals and the description thereof will be omitted.

FIG. 14 shows a substrate S having a large area of rigidity.
The principal part of an apparatus capable of continuously forming a thin film on the surface of the film is shown, and the basic structure of the present film forming apparatus corresponds to the third embodiment shown in FIG. 1 (c). The present film forming apparatus has an opening in the flat surface portion 77 of the electrode block body 76 and the flat surface portion 77.
The reaction gas flow path 5 and the radical gas flow path 6 each having a slit shape inclined at an acute angle are formed substantially parallel to each other, and the substrate S is arranged parallel to the flat surface portion 77 at a predetermined interval. . Further, the reaction gas flow path 5 is open upstream of the radical gas flow path 6. The small blocks of the electrode block body 76 divided by the reaction gas flow path 5 and the radical gas flow path 6 are made into 76a, 76b, and 76c in order from the downstream side, and the small blocks are electrically insulated. And
A high-frequency high voltage is applied between the small blocks 76a and 76b, high-frequency plasma is generated in the plasma generation region P of the portion of the radical gas flow path 6 that is open to the flat portion 77, and the generated radical gas is generated by the substrate S and the flat portion. It merges with the reaction gas flow that has flowed between 77, and a thin film is formed downstream of the merged portion 7. In this case, by relatively moving the substrate S and the electrode block body 76 in parallel, a thin film can be continuously formed in a large area of the substrate S.

FIG. 15 shows a structure in which the electrode block bodies 76 of the film forming apparatus shown in FIG. 14 are arranged in tandem.
Each electrode block body is shown by 78, 79, 80.
Although not shown, each electrode block body 78, 79, 80
Are electrically isolated from each other. The film forming principle of this film forming apparatus is the same as the above, but the above-mentioned electrode block bodies are
Instead of simultaneously supplying gas to the reaction gas flow paths 5 and the radical gas flow paths 6 of 8, 79 and 80, for example, gas is supplied to the electrode block body 80 to perform film formation for a certain period of time, and then the electrode block body 80 That is, the gas supply is stopped and the gas supply to the next electrode block 79 on the downstream side is started, and film formation is performed for a certain period of time. Therefore, in principle, a large area film can be formed without moving the substrate S. However, it is preferable to provide a mechanism for relatively moving the substrate S for the purpose of improving the uniformity of the thin film. Since other configurations are the same as those described above, the same components are designated by the same reference numerals and the description thereof will be omitted.

[0047]

According to the continuous film forming method and apparatus for radical CVD under high pressure according to the present invention as described above, the plasma generating region, that is, the radical generating region and the film forming region are separated, In the plasma generation area, the reaction gas (raw material gas) containing the film-forming element is supplied only to the substrate surface, and a laminar flow of the reaction gas having a uniform thickness and density and a small thickness is formed near the substrate surface. The generated radical gas containing high-density neutral radicals generated in high-pressure plasma of several Torr to several atmospheres is parallel or acutely angled so as not to disturb the flow of the reaction gas in the upper layer of the laminar flow of the reaction gas. Let's merge
The reaction gas is decomposed by the neutral radicals diffused into the reaction gas, and the radical species of the film-forming element generated as a result are deposited on the substrate surface to form a film, so that the substrate is not directly exposed to plasma, that is, high. The film formation can be performed at a low temperature of 300 ° C. or lower without introducing damages such as defects due to charged particles of energy, and the radical species generated by decomposition of the reaction gas can be suppressed from aggregating in the gas phase, As a result, it is possible to prevent the generation of clusters and powders in the vapor phase, and to form a thin film having excellent electrical and optical characteristics on the substrate surface at high speed.

In this case, by relatively moving the substrate in the forward direction or the reverse direction with respect to the flow direction of the reaction gas, a large area or continuous film formation can be performed, which is extremely practical.

If the reaction gas is diluted with an inert gas and supplied to the surface of the substrate, the concentration of the reaction gas (raw material gas) decreases, and the radical species aggregate in the gas phase to form clusters or powders. Therefore, it is possible to reliably suppress the deposition of the reaction gas on the surface of the substrate, and it is possible to improve the utilization efficiency of the reactive gas that is expensive and requires a post-treatment.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of a film forming apparatus of the present invention, in which (a) shows a case where a reaction gas flow and a radical gas flow are combined in parallel to form a film on a single substrate surface. ) Is a case where a reaction gas flow and a radical gas flow are combined in parallel to form a film on the surfaces of two substrates at the same time, and (c) is a case where the reaction gas flow and the radical gas flow are combined at an acute angle to form a single substrate surface. The case of forming a film is shown.

FIG. 2 is a cross-sectional view showing an example of a film forming apparatus of the present invention.

FIG. 3 is also an enlarged cross-sectional view of a main part.

FIG. 4 is an enlarged cross-sectional view of a main part of FIG.

FIG. 5 is an enlarged cross-sectional view of essential parts showing another embodiment of the film forming apparatus of the present invention.

FIG. 6 is a piping diagram showing a gas supply system and an exhaust system.

FIG. 7 is a streamline diagram showing the result of computer simulation of the radical gas flow when the reaction gas flow and the radical gas flow are merged in parallel.

FIG. 8 is a streamline diagram when the partition plate is thinned.

FIG. 9 is a graph showing changes in the amount of silicon deposited with respect to the mixing ratio of helium and hydrogen in radical-generating gas.

FIG. 10 is a graph showing a film formation rate of a silicon film according to a change in a distance from a silane gas joining portion when silane gas is diluted with helium.

FIG. 11 is a sectional view of an essential part of an apparatus for continuously forming a film on the surface of a flexible film.

FIG. 12 is a sectional view of an essential part of an apparatus for continuously and simultaneously forming films on the surfaces of two flexible films.

FIG. 13 is a cross-sectional view of an essential part of an apparatus for continuously and continuously forming films on the surfaces of two substrates.

FIG. 14 is a cross-sectional view of an essential part of an apparatus for continuously forming a film on the surface of a large-area substrate.

FIG. 15 is a sectional view of an essential part of a tandem type film forming apparatus.

[Explanation of symbols]

S, S1, S2 substrate F, F1, F2 flexible film 1 gas flow path 2 substrate surface 3 wall surface 3a parallel surface 3b inclined surface 4 partition plate 4a flat surface portion 4b inclined portion 5 reaction gas flow path 6 radical gas flow path 7 Confluence part 8 Supply means for reaction gas 9 Supply means for radical generation gas 10 Quartz glass tube 11 Upper flange plate 12 Lower flange plate 13 Conductor 14 Insulator 15 Center electrode body 16 Electrode plate 17 Center hole 18 Film forming part 19 Spacer 20 Reaction gas supply pipe 21 Radical generation gas supply pipe 22 Exhaust pipe 23 Cooling pipe 24, 25 Peep window 26 Purge gas supply means 27 Exhaust means 28 Silane gas cylinder 29, 32, 40, 57 Filter 30, 37, 41, 44, 50 diaphragm type regulating valve 31, 42, 48, 52, 53, 55, 58, 60, 6
1,62,63 Open / close valve 33,38,46,59 Flow meter 34,47 Needle valve 35,45,51 Check valve 36,39 Helium gas cylinder 43 Hydrogen gas cylinder 49 Nitrogen gas cylinder 54 Rotary pump 56 Exclusion device 64 Upper surface 65 Guide Member 66 Sliding surface 67,68 Drum 69,70 Guide member 71,72 Partition plate 73 Main electrode body 74,75 Sub-electrode body 76 Electrode block body 76a, 76b, 76c Small block 77 Flat portion 78, 79, 80 Electrode block body

Claims (9)

[Claims] 1. A laminar flow of a reaction gas having a uniform thickness and density and a small thickness is formed in the vicinity of the surface of the substrate, and a few To
rr ~ Neutral radicals diffused into the reaction gas by supplying a radical gas containing high-density neutral radicals generated in high-pressure plasma of several atmospheres to the upper layer of the reaction gas laminar flow without disturbing the flow. A continuous film formation method by a radical CVD method under high pressure, characterized in that the reaction gas is decomposed by and the film forming element is deposited on the substrate surface to continuously form a thin film. 2. The radical CVD under high pressure according to claim 1, wherein the reaction gas is diluted with an inert gas and supplied.
Continuous film formation method. 3. The continuous film forming method by a radical CVD method under high pressure according to claim 1, wherein the reaction gas laminar flow and the radical gas flow are merged in parallel or at an acute angle. 4. A continuous film formation by a radical CVD method under high pressure according to claim 1, 2 or 3, wherein the substrate is moved in a forward direction or a reverse direction relative to a flow direction of a reaction gas. Method. 5. The partition plate and the substrate are formed by forming at least one side wall surface of the gas flow path on the substrate surface and arranging a partition plate in the gas flow path with a minute gap from the substrate surface. Forming a reaction gas flow path with the surface and forming a radical gas flow path with the partition plate and the other side wall surface of the gas flow path facing the substrate surface or between a pair of partition plates, the downstream side of the partition plate The end part is formed as a confluence of the reaction gas flow channel and the radical gas flow channel, a reaction gas supply means containing a film-forming element is provided on the upstream side of the reaction gas flow channel, and a few are provided on the upstream side of the radical gas flow channel.
A high frequency high electric field region for generating high pressure plasma of Torr to several atmospheres is formed, and a means for supplying a radical generating gas such as an inert gas is provided in the region, and a high pressure reaction gas and a radical generating gas are gasified. The reaction gas is supplied from each of the supply means to form a laminar flow of the reaction gas along the surface of the substrate, and a radical gas flow containing high-density neutral radicals generated in high-pressure plasma is formed into the reaction gas laminar flow at the confluence portion. Radical CVD method under high pressure, characterized in that the reaction gas is decomposed by neutral radicals that have been merged and diffused into the reaction gas, and film-forming elements are deposited on the substrate surface to continuously form a thin film. Continuous film forming equipment. 6. A continuous film forming apparatus by a radical CVD method under high pressure according to claim 5, wherein the partition plate is a parallel plate and is arranged parallel to the substrate surface. 7. The radical CVD under high pressure according to claim 5, wherein one surface of the partition plate is arranged parallel to the substrate surface, and the other surface is an inclined surface having an acute angle with respect to the substrate surface.
Continuous film forming apparatus by the method. 8. A continuous film forming apparatus by a radical CVD method under high pressure according to claim 5, 6 or 7, wherein said partition plate also serves as an electrode for plasma generation. 9. The radical CV under high pressure according to claim 5, 6 or 7 or 8, wherein the substrate is relatively moved in parallel in a forward direction or a reverse direction with respect to the flow direction of the gas passage.
Continuous film forming apparatus by method D.