JP2011222991A - Plasma cvd device and thin-film substrate manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma CVD device which can generate plasma in a cathode depressed part (hollow) across a wide area in order to obtain a high-quality amorphous silicon thin-film of a large size with few defects and few inclusion of high-order silane.SOLUTION: A plasma CVD device 1 comprises a vacuum container 2; an exhaust system 6 for retaining the interior of the vacuum container under a reduced pressure; a ground electrode 11 for placing thereon a substrate on which film is formed; a cathode 3 including a plurality of depressed parts 4; a potential shielding plate 8 between the ground electrode 11 and the cathode 3, which has a plurality of lead-through holes 9 formed so as to face the depressed parts 4 each other and is capable of maintaining potential constant; and a high-frequency power supply 15 for applying high-frequency power to the cathode 3. In the plasma CVD device 1, there is provided an ignition assistance plate 10 between the potential shielding plate 8 and the ground electrode 11.

Description

  The present invention relates to a plasma CVD apparatus and a plasma CVD method. In particular, the present invention relates to a plasma CVD apparatus for forming a high-quality amorphous silicon thin film used for a silicon thin film solar cell, a thin film transistor, and the like, and a silicon thin film manufacturing method using a plasma CVD method.

  Compared with single crystal silicon solar cells or polycrystalline silicon solar cells, which are currently the mainstream of solar cells, silicon thin film solar cells are less temperature-dependent and advantageous in terms of cost. It is attracting attention as a battery.

  As a technique for producing an amorphous silicon thin film used for a silicon thin film solar cell, a parallel plate type plasma CVD method is employed. FIG. 6 shows such a conventional parallel plate type plasma CVD apparatus. A conventional plasma CVD apparatus 1 shown in FIG. 6 includes a vacuum container 2 having an exhaust system for maintaining a degree of vacuum. A cathode 3 and a ground electrode 11 for holding a film formation substrate 13 are provided in the container 2. is set up. A deposition target substrate 13 is held on the ground electrode 11, and a heating mechanism 12 for heating the substrate is built in the ground electrode 11. The source gas is uniformly introduced onto the deposition target substrate 13 through the reaction gas introduction path 7 installed in the cathode 3 via an insulator. A high frequency power supply 15 is connected to the cathode 3 via a matching box 14. The cathode 3 is maintained at a constant pressure by an exhaust system, high frequency power is applied to the cathode 3 to generate plasma, and an amorphous silicon thin film is formed on the substrate surface. Form.

  However, it is known that the amorphous silicon thin film produced by such a parallel plate type plasma CVD method increases the neutral dangling bonds (defects) in the film by light irradiation and causes photodegradation. Although this photodegradation has been found as a Staber-Wronski effect more than 30 years ago, it has not been resolved.

Also, the mechanism causing this photodegradation is not clearly elucidated at present, but the Si—H ₂ bond concentration in the film is known as being correlated with the photodegradation, and the Si—H in the film is known. ₂ It has been reported that those with low concentrations have little photodegradation (Non-Patent Document 1). Among them, the cause of the increase in the Si—H ₂ concentration in the film is considered to be a high-order silane radical ((SiH ₂ ) _n : n = 2 to 5) generated during film formation. The secondary silane radical grows by a sequential reaction in which SiH ₂ radicals generated in the plasma are inserted into the Si—H bond, and is mixed into the film, thereby increasing the Si—H ₂ bond and the initial dangling bond. It is supposed to be formed in the film.

It is said that heating the substrate surface temperature from 220 ° C. to 250 ° C. is suitable as means for suppressing such Si—H ₂ bond mixing and dangling bonds (Non-patent Document 1). This is because if the temperature is lower than this range, the surface reaction on the amorphous silicon thin film surface during film formation is suppressed, resulting in a film having many defects, and if the temperature is higher than this range, desorption of hydrogen from the surface occurs. This is because the number of defects increases or damage to the base becomes a problem when a solar cell is manufactured.

In recent years, a triode method has been devised and a film forming method for reducing the Si—H ₂ bond concentration has been proposed. FIG. 7 shows a film formation apparatus of this triode method. As shown in FIG. 7, the plasma CVD apparatus using the triode method has a mesh electrode 17 inserted between the cathode 3 and the ground electrode 11 of the parallel plate plasma CVD apparatus shown in FIG. Is connected. As described above, the triode method is also a parallel plate type CVD method, but by inserting the mesh electrode 17 between the cathode 3 and the ground electrode 11 and applying a potential (usually a negative potential) thereto, the cathode 3 and the mesh electrode. It becomes possible to confine the plasma between 17. Since no plasma is generated between the mesh electrode 17 and the ground electrode 11, radicals that contribute to film formation are generated between the cathode 3 and the mesh electrode 17 and reach the deposition target substrate 13 by diffusion from the gaps in the mesh electrode 17. To do. The radical diffusion distance is proportional to the square root of the inverse of the molecular weight. Since the higher-order silane radical has a large molecular weight, the SiH ₃ radical is selectively transported onto the substrate by utilizing the fact that the diffusion distance is shorter than that of the SiH ₃ radical. Thereby, a very low Si—H ₂ bond concentration is achieved, and an amorphous silicon thin film having a low deterioration rate is obtained (Non-patent Document 2).

However, this technique requires a distance between the mesh electrode and the ground electrode in order to remove higher-order silane radicals. For this reason, if this distance is insufficient, the higher-order silane radicals cannot be removed sufficiently, and if this distance is increased to remove the higher-order silane radicals, there is a problem that the film forming speed is reduced.
Therefore, the inventors have conducted intensive studies and considered that the cathode 3 provided with a plurality of recesses (hollows) 4 as shown in FIG. 8 and the potential shield plate 8 are combined to localize the plasma. By keeping the potential shield plate 8 at the ground potential or negative potential, the plasma is prevented from flowing out onto the deposition target substrate held by the ground electrode 11, and higher-order silane contained in the reaction gas is vacuumed from the exhaust port 6. This is a manufacturing method in which SiH ₃ radicals contained in a plasma source gas are exhausted out of the container and preferentially reach the deposition substrate (Patent Document 1). If this manufacturing method is used, a high-quality amorphous silicon thin film can be obtained at a higher speed than the triode method.

Japanese Patent Application No. 2009-069576

A. Matsuda et al. Solar Energy Materials & Sollar Cells 78 (2003) 3-26 Satoshi Shimizu et al. JOURNAL OF APPLIED PHYSICS 101, 064911, (2007)

However, when the plasma is localized by the potential shield plate, there is a problem that the ignitability of the plasma is poor and it is difficult to generate the plasma in all the recesses (hollows) on the cathode. If there is a recess (hollow) in which plasma is not generated, reaction gas is not excited or decomposed at that portion, the thickness of the opposing portion on the film formation substrate is thin, and the thickness distribution of the thin film is uneven. turn into. If the film thickness distribution is not uniform, for example, in the case of an amorphous silicon solar battery, it becomes difficult to make the current density uniform for each cell, and the conversion efficiency when modularized is lowered.
This problem becomes conspicuous when the cathode has a large area, which hinders cost reduction due to the increase in area.

  Although the ignitability can be improved by increasing the input power only at the time of ignition, an expensive large-capacity power source is required for the manufacturing facility. Furthermore, there is a problem that the interface between the base layer and the base layer and the film formation layer is damaged by applying large electric power.

  Also, if the pressure is reduced only during ignition to ease the localization of the plasma, the plasma will protrude from the recess (hollow) and the ignitability will improve, but the primary purpose is the function of selectively exhausting higher-order silane. Becomes insufficient. There is also a problem that an exhaust system with higher exhaust capacity is required to create a low pressure state at the time of ignition.

  The present invention has been made in view of the above circumstances, and in order to obtain a high-quality amorphous silicon thin film having a low defect and a low level of high-order silane contamination in a large area, a cathode recess (hollow) over a wide area. The purpose is to generate plasma.

In order to solve the above problems, the plasma CVD apparatus of the present invention has the following configuration. That is, a vacuum vessel,
An exhaust system for maintaining the inside of the vacuum vessel under reduced pressure;
A ground electrode for placing a deposition substrate, a cathode having a plurality of recesses,
Between the ground electrode and the cathode,
A plurality of through holes are formed so as to face the concave portion, and a potential shield plate capable of keeping the potential constant,
A high frequency power source for applying high frequency power to the cathode,
It is a plasma CVD apparatus in which an ignition auxiliary plate is installed between the potential shield plate and the ground electrode.

Moreover, in order to solve the said subject, the manufacturing method of the silicon-type thin film of this invention goes through the following processes. That is,
A ground electrode for placing a deposition substrate, a cathode having a plurality of recesses,
Between the ground electrode and the cathode,
In the plasma CVD method using a device provided with a potential shield plate in which a plurality of through holes are formed so as to face the concave portion and the potential can be kept constant,
This is a method of manufacturing a thin film substrate in which plasma is ignited by using an ignition auxiliary plate installed between the potential shield plate and the ground electrode.

  According to the present invention, as will be described below, plasma can be generated in the cathode recess without applying large power during ignition and without changing the pressure low during ignition. This makes it possible to apply high quality amorphous silicon thin film to a large area by plasma confinement using a cathode having a plurality of recesses and a potential shield plate.

It is the schematic which shows the structure of the plasma CVD apparatus by 1st embodiment concerning this invention. It is the schematic which shows the structure of the plasma CVD apparatus by 2nd embodiment concerning this invention. It is the schematic which shows the movement and deformation | transformation mechanism of the ignition auxiliary plate of the plasma CVD apparatus by 1st embodiment concerning this invention. It is the schematic which shows the movement and deformation | transformation mechanism of the ignition auxiliary plate of the plasma CVD apparatus by 1st embodiment concerning this invention. It is the schematic which shows the movement and deformation | transformation mechanism of the ignition auxiliary plate of the plasma CVD apparatus by 1st embodiment concerning this invention. It is the schematic which shows the structure of the conventional plasma CVD apparatus. It is the schematic which shows the structure of the plasma CVD apparatus using the conventional triode method. It is the schematic which shows the structure of the plasma CVD apparatus which combined the cathode provided with the conventional several recessed part, and the electric potential shield board. It is the schematic which shows the structure of the plasma CVD apparatus by 1st embodiment concerning this invention. It is the schematic which shows the movement of the ignition auxiliary plate of the plasma CVD apparatus by 1st embodiment concerning this invention, and a mechanism. It is the schematic which shows the moving mechanism of the ignition auxiliary plate of the plasma CVD apparatus by 1st embodiment concerning this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.

[First embodiment]
FIG. 1 is a schematic diagram showing the configuration of a plasma CVD apparatus according to the first embodiment of the present invention.

  Referring to FIG. 1, a plasma CVD apparatus 1 according to the present invention includes a vacuum vessel 2 having an exhaust system for maintaining a degree of vacuum, a cathode 3 having a plurality of recesses 4 in the vacuum vessel 2, and a film formation substrate. A ground electrode 11 on which 13 is placed is installed.

  A high frequency power supply 15 is connected to the cathode 3 through a matching box 14. The frequency of the high-frequency power source can be arbitrarily selected, and is preferably 100 kHz to 100 MHz, more preferably 10 MHz to 60 MHz, from the viewpoint of productivity and uniformity.

  The film formation substrate 13 may be placed so as not to move on the ground electrode 11. For example, even if the ground electrode 11 is provided with a countersink and the film formation substrate 13 is placed therein, another jig may be used. The deposition target substrate 13 may be pressed against the ground electrode 11. A heating mechanism 12 for heating the film formation substrate 13 is built in the ground electrode 11.

  The cathode 3 is formed with a recess 4 that becomes a space for confining plasma. In addition, the recessed part in this invention does not necessarily need to close a tip like FIG. The concave portion 4 formed in the cathode 3 is connected to a vacuum pump (not shown) through the inside of the cathode 3 and the exhaust port 5 on the upper surface of the electrode, and can be evacuated. If the diameter of the recess 4 is too small, it is difficult to generate plasma inside the recess 4 and a sufficient exhaust capacity cannot be obtained. On the other hand, if it is too large, the difference in plasma intensity between the center and the edge of the recess 4 becomes large, and the film thickness distribution of the film formation substrate 13 deteriorates. Therefore, the preferable range is 2 mm or more and 100 mm or less, and more preferably 5 mm or more and 50 mm or less. Further, considering the film thickness distribution on the film formation substrate 13, it is preferable that the recesses 4 are arranged uniformly on the discharge electrode surface 5.

  A raw material gas introduction path 7 for supplying a raw material gas is formed in the cathode 3. The source gas introduction path 7 passes through the cathode 3 and the potential shield plate 8. The raw material gas is introduced into the raw material gas introduction path 7 by controlling the flow rate by a mass flow controller (not shown) and supplied into the vacuum vessel 2.

  The exhaust during film formation may be exhaust from only the exhaust port 6 formed on the upper part of the cathode 3, but there is no problem if the pressure is adjusted by providing an exhaust system other than this.

Silane gas (SiH ₄ ) is generally used as the source gas, but it is also possible to select a gas such as disilane (Si ₂ H ₆ ), methylsilane, metal halide, diborane, or phosphine. Further, it may be diluted with hydrogen, an inert gas such as helium or argon.

  Further, as in the plasma CVD apparatus of FIG. 1, a plurality of through holes 9 are formed between the cathode 3 and the ground electrode 11, and a potential shield plate 8 is installed to keep the potential constant.

  The purpose of installing the potential shield plate 8 is to localize the plasma inside the recess 4 formed in the cathode 3 and to incorporate elements of the triode method. For this purpose, grounding the potential shield plate 8 or connecting the DC variable power source 16 or the like to the potential shield plate 8 and applying a potential is a very effective means for controlling plasma. By setting the potential shield plate 8 to the ground potential or the negative potential, the plasma can be confined in the recess 4 and the plasma existing between the potential shield plate 8 and the deposition target substrate 13 can be weakened. The power supply 16 connected to the potential shield plate 8 is not a problem as long as a potential can be applied, and a self-bias can be generated and a DC potential can be applied to an AC power supply having a frequency of the order of kHz or higher. In addition, an AC power source or an RF power source of about kHz may be used. If the ground potential is to be used, the power source 16 is not necessary and it may be grounded as it is.

  In consideration of plasma confinement, it is preferable that the central axis of the through hole 9 of the potential shield plate 8 is arranged so as to overlap the central axis of the recess 4 formed in the cathode 3. It is considered that cylindrical plasma due to hollow cathode discharge is generated in the recess 4, and when the through-hole 9 and the center axis of the recess 4 coincide with each other, from the plasma to the potential shield plate 8 having a ground potential or a negative potential. This is because the distance between the two becomes equal and the plasma discharge is stabilized. Further, if the diameter of the through hole 9 of the potential shield plate 8 is too larger than the diameter of the concave portion 3, it causes plasma leakage, and if it is too narrow, diffusion of active species from the plasma is suppressed and the film formation rate cannot be maintained. The range is 0.5 to 2 times, more preferably 0.7 to 1.5 times the diameter of the recess 4. The shape of the through hole 9 of the potential shield plate 8 may be a taper shape or the like.

By confining the plasma in the recess 4 in this way, the plasma is present in the exhaust flow. For this reason, high-order silane with a short diffusion length is exhausted by the flow of exhaust gas, and SiH ₃ radicals with a long diffusion length can reach the substrate direction by diffusion.

Further, since the plasma between the potential shield plate 8 and the deposition target substrate 13 is weakened, the generation of new active species between the potential shield plate 8 and the deposition target substrate 13 is almost eliminated. As a result, higher-order silane, SiH ₂ radicals, and SiH ₃ radicals that contribute to film formation are limited to those diffused from the through holes 9 of the potential shield plate 8 toward the film formation substrate 13.

The following reaction can be considered as a reaction occurring between the potential shield plate 8 and the film formation substrate 13.
Si _m H _{2m + 1} + SiH ₄ → Si _m H _{2m + 2} + SiH ₃ (m is an integer of 2 or more)
(1)
SiH ₂ + SiH ₄ → Si ₂ H ₆ (2)
SiH ₃ + SiH ₄ → SiH ₄ + SiH ₃ (3)
Higher order silane radicals diffused in the direction of the film formation substrate 13 against the flow of exhaust gas react with the parent molecule SiH ₄ during the diffusion in the direction of the film formation substrate 13 to become inactive higher order silanes. The air is exhausted without being involved in the film formation (1). SiH ₂ radicals are exhausted without being involved in film formation by reacting with SiH _{4 as a} parent molecule and becoming inactive in the process of growing into higher-order silane while diffusing (2). On the other hand, the SiH ₃ radical (3) that does not change by reaction with the parent molecule reaches the substrate and selectively contributes to film formation, whereby a high-quality film can be obtained.

An auxiliary ignition plate 10 is installed between the potential shield plate 8 and the ground electrode 11. The presence of the auxiliary ignition plate 10 changes the distance between the electrodes in Paschen's law from the distance between the cathode 3 and the ground electrode 11 to the distance between the negative electrode 3 and the auxiliary ignition plate 10 and facilitates ignition and discharge maintenance. To.
The auxiliary ignition plate 10 may be grounded, or may be connected to a DC power source 16 or the like as shown in FIG. Since the potential in the Paschen's law is the difference between the potential of the cathode 3 and the potential of the auxiliary ignition plate 10, it is possible to ignite well even at various film forming pressures by adjusting the applied potential.
It is preferable that the distance between the auxiliary ignition plate 10 and the potential shield plate 8 can be changed. Since the distance between the auxiliary ignition plate 10 and the potential shield plate 8 is the distance between the electrodes according to Paschen's law, it is possible to ignite satisfactorily even at various deposition pressures by changing this value.
The auxiliary ignition plate 10 can cover 50% or more, more preferably 75% or more, of the smaller area of the cathode 3 and the deposition target substrate 13 at the time of ignition, and moves or deforms after the ignition ends to move the cathode. 3 and the smaller one of the deposition target substrate 13 are preferably 25% or less, more preferably 10% or less of the smaller area of the cathode 3 and the deposition target substrate 13.
By covering the cathode 3 or the film formation substrate 13 during ignition, damage to the film formation substrate 13 due to unstable discharge during ignition can be avoided. As shown in FIG. 9, it is more preferable to provide the side wall 18 at the edge of the auxiliary ignition plate 10 because unstable discharge hardly leaks onto the film formation substrate 13. The side wall 18 may be provided on both the cathode 3 side and the ground electrode 11 side of the potential control plate 10, or may be provided on either side, but is more preferably provided only on the ground electrode 11 side. This is to avoid abnormal discharge that may occur if there are irregularities between the auxiliary ignition plate 10 and the cathode 3, and to avoid it. If the area covering the cathode 3 or the film-forming substrate 13 is smaller than 50% of the smaller area of both, unstable discharge at the time of ignition leaks onto the film-forming substrate 13, and the above-mentioned effects are sufficiently exhibited. There are cases where it is not possible.
After the ignition is finished, if the ignition auxiliary plate 10 covers the cathode 3 or the film formation substrate 13, a film to be deposited on the film formation substrate 13 is deposited on the ignition auxiliary plate 10, and the film formation speed is reduced. Therefore, it is preferable that the auxiliary ignition plate 10 can be moved or deformed so that the area covering the cathode 3 or the deposition target substrate 13 is 25% or less of the smaller area of both.
For the movement or deformation of the auxiliary ignition plate 10, for example, mechanisms as shown in FIGS. Note that the present invention is not limited to these examples. FIG. 3 shows a mechanism in which the auxiliary ignition plate 10 is divided and moved from above the film formation substrate 13. Since this mechanism has a simple structure, there is an advantage that installation and maintenance are easy. Further, since the auxiliary ignition plate 10 can be completely removed from the deposition target substrate 13, there is an advantage that the above-described decrease in the deposition rate can be minimized. FIG. 4 shows a mechanism in which the ignition auxiliary plate 10 is deformed like a blind. Since this mechanism does not require a space for moving the auxiliary ignition plate 10, there is an advantage that the size of the vacuum vessel can be reduced. FIG. 5 shows a mechanism in which the ignition hook plate 10 moves and deforms like a sliding door. This has an intermediate characteristic between FIG. 3 and FIG. FIG. 10 shows a mechanism in which the auxiliary ignition plate 10 only moves and does not deform. Since the inside of the vacuum vessel of the CVD apparatus has spatial and electrical restrictions, this mechanism having a simple structure is particularly suitable when the present invention is applied by modifying an existing apparatus. FIG. 11 shows a structure in which a side wall 18 is attached to the edge of the ignition auxiliary plate 10 of FIG. When the auxiliary ignition plate 10 is smaller than the cathode 3 or the film formation substrate 13 due to space restrictions or the like, the presence of the side wall 18 reduces leakage of unstable discharge during ignition onto the film formation substrate 13. be able to.

[Second Embodiment]
In the plasma CVD apparatus according to the second embodiment, the positions of the exhaust port 6 and the reaction gas introduction path 7 of the plasma CVD apparatus according to the first embodiment are changed as shown in FIG. In the second embodiment, the exhaust flow does not coincide with the direction away from the deposition substrate 14, so the effectiveness of detoxification of higher order silane using the exhaust flow is reduced compared to the first embodiment, but the electrode structure is It has the advantage that it can be simplified, and is suitable when remodeling existing equipment.
Even if the reaction gas is supplied or exhausted not from the cathode 3 but from the side surface or the lower surface of the vacuum vessel 2, the same effect as that of the first embodiment can be obtained in the plasma ignitability to the cathode recess which is the object of the present invention. .

Using the plasma CVD apparatus of the present invention described above, the deposition target substrate 13 is placed on the ground electrode 11 and evacuated, then the source gas is introduced from the source gas introduction path 7, and the high frequency power source 15 is used for powering. When plasma is introduced, plasma can be generated in the recess (hollow) 4 over the entire area of the cathode 3.
(Example 1)
Having the structure shown in FIG. 10 in the first embodiment,
The vacuum pump is a mechanical dry pump,
The size of the surface of the cathode 3 facing the ground electrode 11 is 180 mm × 180 mm, the distance between the cathode 3 and the ground electrode 11 is 45 mm,
The cathode 3 is formed with 85 hollows 4 having a diameter of 10 mm and a depth of 40 mm,
The distance between the cathode 3 and the potential shield plate 8 is 1 mm,
The same number of through-holes 9 having a diameter of 10 mm as the recesses (hollows) are formed in the potential shield plate 8 so that the central axis coincides with the recesses (hollows) 4 on the cathode 3.
An apparatus in which the distance between the cathode 3 and the auxiliary ignition plate 10 is 30 mm was used.
At the time of ignition, the auxiliary substrate 10 having an area of 144% of the area of the film formation substrate 13 covers the film formation substrate 13, and after the ignition is finished, the auxiliary ignition plate 10 is moved to the side and the film formation substrate 13 is moved. I tried not to cover it.
The frequency of the high frequency power supply 15 is 60 MHz,
The potential of the potential shield plate 8 is set to 0 V (ground),
The potential of the auxiliary ignition plate 10 was set to 0 V (ground).
Using SiH ₄ as source gas,
The flow rate is 50 sccm,
The pressure is 25 Pa,
The temperature of the ground electrode 11 is 210 ° C.
The temperature of the potential shield plate 8 is 210 ° C.
Ignition was performed under the condition of electric power of 40 W, and then the auxiliary ignition plate 10 was moved to form an amorphous silicon film for 60 minutes.
As a result, plasma was generated in all of the concave portions (hollows) 4 of the cathode 3, and the film thickness distribution defined below was within 10%.
The film thickness distribution is obtained by measuring the film thickness at a total of five locations, the center of the film formation substrate placed directly under the center of the cathode 3 and the position of every 90 ° on a circle with a radius of 20 mm with the position as the origin. From the measured value, the following formula was used.
Film thickness distribution (%) = {(maximum value of film thickness at each position−minimum value of film thickness at each position) /
(Maximum film thickness at each position + minimum film thickness at each position)} × 100
(Example 2)
When an amorphous silicon film was formed for 60 minutes under the same apparatus and conditions as in Example 1 except that the power was 30 W, plasma was generated only in 72 of the recesses 4 of the cathode 3, and the film The thickness distribution was 15%.
(Example 3)
When an amorphous silicon film was formed for 60 minutes under the same apparatus and conditions as in Example 1 except that the distance between the cathode 3 and the auxiliary ignition plate 10 was 18 mm, all the recesses (hollows) 4 of the cathode 3 were formed. Plasma was generated and the film thickness distribution was within 10%.
Example 4
An amorphous silicon film was formed for 60 minutes under the same apparatus and conditions as in Example 1 except that the distance between the cathode 3 and the auxiliary ignition plate 10 was 18 mm and the power was 30 W. ) Plasma was generated in all 4 and the film thickness distribution was within 10%.
(Comparative Example 1)
When the auxiliary ignition plate 10 was removed from the apparatus of (Example 1) and an amorphous silicon film was formed for 60 minutes under the same conditions as in (Example 1), only 56 of the recesses (hollows) 4 of the cathode 3 were formed. Plasma was generated, and the film thickness distribution was 21%.

  By comparing (Example 1) and (Comparative Example 1), it can be seen that it is easy for the auxiliary ignition plate 10 to generate plasma over the entire area of the cathode 3 and a good film thickness distribution is obtained. Further, by comparing (Example 2) and (Example 4), it is possible to further easily generate plasma in the entire area of the cathode 3 by adjusting the distance between the auxiliary ignition plate 10 and the cathode 3. I understand.

  The present invention can be applied not only to plasma CVD apparatus and amorphous silicon thin film formation, but also to various thin film formation such as microcrystalline silicon thin film, etching apparatus, plasma surface treatment apparatus, etc. It is not limited to.

DESCRIPTION OF SYMBOLS 1 Plasma CVD apparatus 2 Vacuum vessel 3 Cathode 4 Recess 5 Cathode surface 6 Exhaust port 7 Reactive gas introduction path 8 Potential shield plate 9 Through hole 10 Auxiliary ignition plate 11 Ground electrode 12 Substrate heating mechanism 13 Substrate for deposition 14 Matching box 15 High frequency Power source 16 DC power source 17 Mesh electrode 18 Side wall

Claims (8)

A vacuum vessel;
An exhaust system for maintaining the inside of the vacuum vessel under reduced pressure;
A ground electrode for placing a deposition substrate, a cathode having a plurality of recesses,
Between the ground electrode and the cathode,
A plurality of through holes are formed so as to face the concave portion, and a potential shield plate capable of keeping the potential constant,
A high frequency power source for applying high frequency power to the cathode,
A plasma CVD apparatus in which an ignition auxiliary plate is installed between the potential shield plate and the ground electrode.   The plasma CVD apparatus according to claim 1, wherein the distance between the auxiliary ignition plate and the potential shield plate can be changed. The ignition auxiliary plate is
Cover 50% or more of the smaller one of the cathode and the deposition substrate at the time of ignition,
3. The plasma CVD apparatus according to claim 1, wherein the plasma CVD apparatus is configured to cover 25% or less of the area by moving or deforming after completion of ignition. A ground electrode for placing a deposition substrate, a cathode having a plurality of recesses,
Between the ground electrode and the cathode,
In the plasma CVD method using a device provided with a potential shield plate in which a plurality of through holes are formed so as to face the concave portion and the potential can be kept constant,
A method of manufacturing a thin film substrate in which plasma is ignited using an ignition auxiliary plate installed between the potential shield plate and the ground electrode.   5. The method of manufacturing a thin film substrate according to claim 4, wherein ignition is performed after changing the distance between the ignition auxiliary plate and the cathode by moving the ignition auxiliary plate in a direction perpendicular to the plane of the ignition auxiliary plate. The ignition auxiliary plate covers 50% or more of the smaller one of the cathode and the deposition target substrate during ignition;
6. The method of manufacturing a thin film substrate according to claim 4, wherein the film is formed with the area being 25% or less after the ignition is finished.   The plasma CVD apparatus according to claim 1, wherein a side wall is formed on an edge of the auxiliary ignition plate.   The method of manufacturing a thin film substrate according to claim 4, wherein plasma is ignited using the ignition auxiliary plate having a side wall formed on an edge.

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