JPH11152577A - Formation of deposited coating and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating forming method in which stable discharge is maintained for a long time and the application of bias electric power is sufficiently and efficiently executed by a microwave plasma CVD method jointly using bias electric power and capable of forming homogeneous functional deposited coating uniform in coating thickness and having excellent electric characteristics with reproducibility at a high deposition rate and to provide a device therefor. SOLUTION: In a method in which a gaseous starting material is introduced into a discharge space (1003), simultaneously, microwave electric power is introduced into the discharge space, and further, bias electric power is applied to the inside of the discharge space to generate plasma discharge, by which the gaseous starting material is cracked to form deposited coating on a continuously moving belt-like substrate (1004) for coating formation, the application of the bias electric power is executed via an electrode (1005) having a shape and a structure in which the surface are in the discharge space is larger than the surface area in the discharge space on the whole body of an anode (ground) electrode including the surface area of the belt-like substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible to continuously form a desired functional deposited film on a long substrate for mass production of semiconductor devices such as photovoltaic elements (solar cells). A method and an apparatus for forming a deposited film.

[0002]

2. Description of the Related Art U.S. Pat. No. 4,400,409 discloses a roll-to-roll method for continuously forming a functional deposition film used for a photovoltaic element or the like on a substrate. A plasma CVD method employing a (Roll) method is disclosed. According to this method, a semiconductor junction of a desired conductivity type is formed in a plurality of glow discharge regions on a long strip-shaped substrate, and the substrate is continuously transported in the longitudinal direction to form a semiconductor junction. It is described that the element having the above can be continuously formed. However, forming a desired semiconductor layer on a belt-shaped substrate of several hundred meters requires a long deposition time, and at this time, a uniform and reproducible discharge state is constantly maintained and controlled. Need to do. In addition, it is necessary to form a high-quality and uniform semiconductor deposition film continuously and with high yield over the entire length of the long strip-shaped base from the beginning to the end. For example, when forming an i-type semiconductor layer composed of an amorphous silicon semiconductor film of a photovoltaic element, the main source gas S
An i-type semiconductor film can be obtained by mixing a silane gas such as iH ₄ with a H ₂ gas and decomposing it by glow discharge. In particular, the quality of the i-type semiconductor layer greatly affects the characteristics of the photovoltaic device. Doing is well known. On the other hand, in order to realize a large number of photovoltaic elements at a low cost, it is required to improve the throughput of a film forming apparatus to be used. One of the factors hindering this is i-type semiconductors. Instability of microwave discharge forming the layer and discharge breakage are mentioned. It is desired to provide a means for solving the stability of the microwave discharge over such a long time as soon as possible.

In the above-described microwave discharge for forming the i-type semiconductor layer, in addition to introducing microwave power into the discharge space, the microwave power is supplied through a bias power introduction electrode provided in the discharge space. It is known that introducing bias power such as RF power into the discharge space is effective in improving the film quality of the i-type semiconductor layer. A film forming apparatus for performing this method has, for example, a configuration as shown in FIG. FIG. 3A is a perspective view, and FIG. 3B is a view of the device shown in FIG. In FIGS. 3A and 3B, 200
Reference numeral 1 denotes a microwave applicator connected to a microwave power supply (not shown); 2002, a microwave introduction window (microwave fin-shaped window); 2003, a discharge furnace (discharge space);
Reference numeral 4 denotes a band-shaped member (a band-shaped base) for film formation, 2005 denotes a rod-shaped or similar bias applying electrode, 2006
Denotes a source gas introducing means (gas manifold), and 2007 denotes a reaction vessel wall. FIG. 2 (a) and FIG.
In the film forming apparatus shown in (b), a microwave is introduced into a discharge furnace 2003 surrounded by a strip-shaped substrate 2004 and a reaction vessel wall 2007 to generate plasma, and the raw material gas introduced into the discharge furnace is decomposed. Then, a deposited film is formed on the belt-shaped substrate 2004. At this time, a bias power such as DC or RF is superimposed via a bias application electrode 2005 installed in the discharge furnace 2003. The surface area of the bias application electrode is obviously smaller than the total surface area of the anode (ground) electrode including the band-shaped substrate 2004.

[0004]

In the internal structure of the discharge furnace in the above-mentioned conventional film forming apparatus, particularly in the structure of the bias applying electrode, the discharge itself is caused by abnormal discharge such as spark or local overheating of the bias applying electrode. May become unstable. Therefore, it is desired to provide means for stabilizing microwave discharge for a long period of time and to sufficiently and effectively introduce bias power into a discharge furnace (discharge space), and to provide a device structure. I have. The present invention solves the above-mentioned problems in the prior art and, in response to the above-mentioned demands, provides a functionally deposited film having excellent electrical characteristics with good reproducibility and high deposition by a microwave plasma CVD method using bias power. It is an object of the present invention to provide a film forming method and an apparatus capable of forming at a high speed. According to the present invention, a stable discharge is maintained for a long time, and the bias power is sufficiently and efficiently applied by the microwave plasma CVD method using the bias power together. And high-quality photovoltaic device (solar cell) that can form an i-type semiconductor film having excellent electrical characteristics with good reproducibility and high deposition rate
It is an object of the present invention to provide a film forming method and an apparatus that enable mass production of semiconductor devices such as the above.

[0005]

The present invention has been completed as a result of intensive studies to solve the above-mentioned problems in the prior art and to achieve the above object. In the present invention, the instability of microwave discharge, which is a drawback in the technique of forming a film on a long belt-like substrate by the conventional microwave plasma CVD method using bias power together with the bias power, is improved to stabilize it for a long time. In order to apply the bias power more effectively, the following measures are taken. That is, an electrode installed in the same discharge space of the microwave discharge furnace for applying RF power, DC power, or the like as bias power is an anode (ground) electrode whose surface area in the discharge space includes the surface area of the strip-shaped base. The structure is to be larger than the surface area in the entire discharge space. The present invention includes a deposited film forming method and apparatus described below. In the method of forming a deposited film of the present invention, a plasma discharge is generated by introducing a raw material gas into a reaction vessel having a discharge space, simultaneously introducing microwave power into the discharge space and bias power into the discharge space. In the method of forming a deposited film on a film-forming substrate that is continuously moved by decomposing the source gas by causing the introduction of the bias power, the surface area in the discharge space is reduced by the surface area of the band-shaped substrate. The process is performed through an electrode having a shape and structure larger than the surface area of the entire anode (ground) electrode including the discharge space. The deposited film forming apparatus of the present invention includes a reaction vessel having a discharge space for forming a film on a continuously moving band-shaped substrate, and a film-forming surface of the band-shaped substrate exposed to the discharge space. Means for continuously moving, the reaction vessel having a microwave introduction means for introducing microwave power into the discharge space, and a source gas introduction for introducing a source gas into the discharge space. Means, a bias power application electrode for applying bias power to the discharge space, and an exhaust means for exhausting the inside of the reaction vessel, and a source gas is introduced into the discharge space by the source gas introduction means. At the same time, microwave power and bias power are introduced into the discharge space by the microwave introduction means and the bias power application electrode, respectively, to generate plasma discharge. In a deposition film forming apparatus for forming a deposition film on the strip-shaped substrate moving continuously by decomposing a raw material gas, the bias power application electrode may be an anode (ground) having a surface area in the discharge space including the surface area of the strip-shaped substrate. A) the electrode has a shape and structure larger than the surface area of the entire electrode in the discharge space.

In the present invention, the structure of the electrode for applying the bias power can be, specifically, any of the structures described below. (1) A structure in which no discharge occurs on the back side of the electrode opposite to the discharge space; (2) A structure surrounding the outer periphery of the discharge space and enclosing the entire discharge space inside; (3) In the discharge space Structure having slit-like or similar holes so as not to hinder the propagation of microwaves, however, it is not preferable to make these slit-like or similar holes larger than necessary, and plasma discharge It is necessary to make the holes smaller than the size that does not leak out of the discharge space. (4) The flow of the raw material gas introduced into the discharge space and the flow of the gas exhausted from the discharge space (reaction vessel) are required. A structure having a slit-like or similar hole so as not to hinder, however, it is not preferable that these slit-like or similar holes have an unnecessarily large opening, It is necessary that the plasma discharge is in the order of magnitude less hole does not leak to the outside of the discharge space.

In the present invention, the excitation reaction and the decomposition reaction of the raw material gas are not promoted only in a certain limited portion near the bias power application electrode, and the anode electrode including the strip-shaped base rather than the entire discharge space is not promoted. On the side, the excitation reaction of the raw material gas, the decomposition reaction is promoted,
A functional deposition film such as an i-type semiconductor film can be efficiently and uniformly deposited on the belt-like substrate at a relatively high deposition rate. That is, the amount of DC or RF power applied to the bias power application electrode (cathode electrode) is adjusted well, and the applied high frequency power is used more effectively to efficiently excite the source gas introduced into the discharge space. It contributes to activation or decomposition, whereby a high-quality non-single-crystal functional deposition film can be deposited uniformly and reproducibly at a relatively high deposition rate on the strip-shaped substrate. In the present invention, the constituent material of the bias power application electrode (cathode electrode) can be stainless steel and its alloy, aluminum and its alloy, and the like. In addition, other materials having conductive properties may be used. Similarly, a reaction vessel wall having a discharge space functioning as an anode electrode and a strip-shaped substrate can be made of these materials. In the present invention, as described above, as a result of increasing the area of the bias application electrode, it is possible to reduce the applied power value per unit area on the electrode surface, thereby significantly suppressing the occurrence of abnormal discharge due to sparks or the like. Therefore, the discharge can be stably generated and maintained for a long time. Conversely, this means that
The absolute value of the bias power that can be applied to one bias power application electrode should be greater than or equal to the power value that was conventionally difficult to apply due to discharge failure, that is, an effective large bias power value should be applied. It is possible to improve the quality of the deposited film formed by applying a large bias power to the gas molecules in the discharge space more effectively. According to the present invention, when a semiconductor film is formed on a belt-shaped member (belt-shaped base) having a length of several hundred meters, a uniform and reproducible discharge state is maintained and controlled over a long deposition time. It is possible to continuously and efficiently form a desired semiconductor film having a high quality and a uniform film thickness over the entire length of the long belt-shaped member from the beginning to the end. In particular, for example, when a non-single-crystal i-type semiconductor film for a photovoltaic element (solar cell) is formed, the utilization efficiency of the source gas can be significantly improved, and even when the deposition rate is relatively high, the uniformity can be obtained. Thus, a very high-quality i-type semiconductor film can be formed. That is, the throughput of the film forming apparatus can be significantly improved.

In the present invention, for example, when forming a functional deposition film for a photovoltaic element (solar cell), the raw material gas is gaseous at room temperature containing silicon atoms or can be easily gasified. Compounds, compounds containing germanium atoms that are gaseous or readily gasifiable at room temperature, compounds containing carbon atoms that are gaseous or easily gasifiable at room temperature, and mixtures of these compounds be able to. Examples of the compound containing a silicon atom include SiH ₄ , Si
_{2 H 6, SiF 4, SiFH} 3, SiF 2 H 2, SiF 3 H,
Si ₃ H ₈ , SiD ₄ , SiHD ₃ , SiH ₂ D ₂ , SiH ₃
D, SiFD ₃ , SiF ₂ D ₂ , SiD ₃ H, Si ₂ D ₃ H ₃
And the like. Examples of the compound containing a germanium atom include, for example, GeH ₄ , GeD ₄ , G
eF ₄ , GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeH
_{D 3, GeH 2 D 2,} GeH 3 D, and the like _{Ge 2 H 6, Ge 2 D} 6. Examples of the compound containing a carbon atom include CH ₄ , CD ₄ , CnH _{2n + 2} (n is an integer), CnH _2n (n is an integer), C ₂ H ₂ , C ₆ H ₆ , C
O ₂ , CO and the like can be mentioned. In addition to these source gases, compounds such as N ₂ , NH ₃ , ND ₃ , NO, NO ₂ and N ₂ O can be used for supplying nitrogen atoms. Further, compounds such as O ₂ , CO, CO ₂ , NO, NO ₂ , and N ₂ O can be used for supplying oxygen atoms. The above compounds are represented by H ₂ , He, Ne, Ar, Xe,
It may be diluted with a gas such as Kr and introduced into a film formation chamber (a reaction vessel having a discharge space).

Hereinafter, a deposited film forming apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating an example of a deposited film forming apparatus (hereinafter, simply referred to as a film forming apparatus) of the present invention. FIG. 1A is a schematic perspective view, and FIG.
2B is a diagram of the film forming apparatus shown in FIG. In FIG. 1A and FIG. 1B, 1001
Denotes a microwave applicator connected to a microwave power supply (not shown), 1002 denotes a microwave introduction window (microwave fin-shaped window), and 1003 denotes a discharge furnace (discharge space). Reference numeral 1004 denotes a long band-shaped member as a film-forming substrate (hereinafter, the band-shaped member may be referred to as a band-shaped substrate), and the band-shaped member is formed as shown in FIGS. 1A and 1B. The film-forming surface can be conveyed from left to right while exposing the film-forming surface to the discharge space 1003 by a conveying means (not shown). 1005 is a box-shaped bias power application electrode that functions as a cathode electrode. Reference numeral 1006 denotes a source gas introduction unit (gas manifold) connected to a source gas supply source (not shown), and the source gas is supplied to the discharge space 10.
03 (discharge furnace) is provided with a plurality of gas discharge holes for discharge into the discharge furnace. 1007 indicates a reaction vessel wall. In this example, the box-shaped bias power application electrode 1005 is
It comprises a box-shaped bias power applying electrode with a slit as shown in FIG. As shown in FIGS. 1A and 1B, the box-shaped bias power application electrode is provided so as to surround the discharge space 1003, and includes an anode (eg, a reaction vessel wall 1007) facing the outside thereof. It is electrically insulated from the (ground) electrode using an insulating insulator (not shown) or the like. In the reaction vessel, that is, the discharge space 1
003 (discharge furnace) can be evacuated through a reaction vessel wall 1007 as shown in FIG.

As shown in FIG. 2A, the box-shaped bias power applying electrode shown in FIG. 2A has a plurality of slit-shaped holes formed in the four wall plates in a direction parallel to the band-shaped member 1004. It is of the structure provided. The band-shaped member 1004 is
It is supported by a magnet roller (not shown) and can be moved in the transport direction shown in FIGS. 1A and 1B without physically contacting the discharge furnace 1003 and the microwave fin-like window 1002 located below. It has a simple structure. The source gas is
The gas is introduced from the gas manifold 1006 into the electric discharge furnace 1003, and is exhausted from the electric discharge furnace 1003 to the outside of the electric discharge furnace 1003 by a vacuum pump (not shown) from the exhaust ports (not shown) at the front and rear sides in FIGS. You. In this example, the strip-shaped member 1004 functioning as the anode electrode and the reaction vessel wall 1007 are made of stainless steel SUS316. The box-shaped bias power application electrode 1005 is also made of stainless steel SUS316. In the film forming apparatus of the present example, microwave power is introduced from a microwave power supply (not shown), through an applicator 1001, through a microwave fin window 1002, and into a discharge furnace 1003. Also, the bias power application electrode 1005 includes:
RF power is applied from a high frequency power supply (not shown). The discharge region of the generated plasma discharge is a discharge furnace 1 surrounded by a box-shaped bias power application electrode 1005 and a band-shaped member 1004.
003 space. When a microwave discharge furnace having such a structure is used, the ratio of the surface area of the box-shaped bias power application electrode 1005 to the area of the grounded anode electrode including the band-shaped member 1004 is clearly larger than 1. . On the other hand, the conventional microwave discharge furnace is as shown in FIG. 3, as described above, and the bias power application electrode used is generally a rod or a similar shape. As is clear from FIG.
3 of the surface area of the bias power application electrode 2005 in contact with
The ratio of the area of the grounded anode electrode including the band member 2004 to the area is obviously smaller than 1.
The shape of the bias power application electrode 1005 functioning as the cathode electrode in the present invention is not limited to the above-described configuration shown in FIG.
Other shapes as shown in (d) may be used. FIG.
The box-shaped bias applying electrodes shown in FIGS.
In the case of this example, it is made of stainless steel SUS316. The bottom plate portion of the box-shaped bias power application electrode shown in FIGS. 2A to 2D is not provided with a slit or a similar hole. However, a slit-shaped hole or the like may be separately provided in the bottom plate portion. The box-shaped bias power application electrode shown in FIG.
A structure in which a plurality of slit-shaped holes are provided in a direction parallel to the slit 04 and the other two wall surfaces are provided with a slit-shaped hole in a vertical direction. The slit-shaped hole transmits microwaves,
Any structure may be used as long as it has a size and shape that does not hinder gas introduction and exhaust and does not impair the function as a bias power application electrode. For example, a shape as shown in FIG. Good. The box-shaped bias power application electrode shown in FIG. 2D has an eave-shaped plate on its upper part, and only a portion corresponding to a portion through which the band-shaped member 1004 passes is opened, so that the discharge space can be further wrapped. It has a structure of The shape of the bias power application electrode in the present invention is not limited to those shown in FIGS. 2A to 2D described above, and may be other shapes. That is, for example, although not shown, a shape constituted by non-linear sides or surfaces may be used, and the holes formed in the electrode surfaces are not necessarily limited to slit shapes and circular shapes. Any size and shape may be used as long as the transmission of microwaves, the introduction and exhaust of gas, and the like are not hindered, and the plasma discharge does not leak out of the discharge space formed by the box-shaped bias power application electrode. Furthermore, the discharge space 1
Regarding the ratio of the surface area of the portion of the bias power application electrode in contact with the generated plasma to the surface area of the anode electrode (ground potential) portion in contact with the plasma in 003, the area of the bias power application electrode is It is preferable that the shape has at least a value larger than 1. As a means for changing the area ratio, for example, the size and number of holes such as slits formed on the surface of the bias power application electrode, the arrangement in the plane, or the like may be changed. As a method of the above, the height l1 of the box-shaped bias power application electrode is
It can also be realized by changing (described in FIGS. 2A to 2D).

FIG. 4 shows a roll used for manufacturing a single cell type photovoltaic element by applying the present invention.
It is a figure which shows typically the structure of an example of the plasma CVD apparatus of a two-roll (Roll to Roll) system.
In the apparatus shown in FIG.
The conductive layer forming vacuum container 302, the i-type layer forming vacuum container 303, the second conductive layer forming vacuum container 304, and the take-up container 305 are connected via respective gas gates 306, and a belt-shaped member 308 ( And a transport system capable of continuously transporting the belt-like substrate under vacuum conditions. A discharge furnace 331 according to the present invention is provided in a vacuum vessel 303 for forming an i-type layer. The microwave is introduced into the discharge furnace 331 from a microwave power supply (not shown) via the waveguide 330.

[0012]

The present invention will be further described with reference to the following examples. The present invention is not limited by these examples.

[0013]

[Embodiment 1] An RF bike having a shape as shown in FIG.
Use a grounded power application electrode to
Of the bias power application electrode to the entire
Box-shaped bias power applied voltage with 3.2 times the surface area ratio
A microwave discharge furnace with a pole structure was fabricated. The microphone
The microwave discharge furnace is a roll-to-roll type shown in FIG.
In the plasma CVD apparatus, the i-type layer forming vacuum vessel 30
Bias power application electrode of microwave discharge furnace 331 in 3
It was installed as. In this embodiment, the plasma CVD apparatus is used.
Under the conditions shown in Table 1, a 0.13 mm thick
Strip base made of stainless steel (SUS430BA)
A first conductivity type layer and an i-type layer on the lower electrode formed thereon;
Layer, the second conductivity type layer is formed by the procedure shown below,
A single cell type photovoltaic element (element-real 1)
Made sequentially. First, a vacuum with a substrate delivery mechanism
The container 301 is sufficiently degreased and cleaned to serve as a lower electrode.
And a 100 nm thick silver thin film and 1
Stainless steel with a ZnO film of μm thickness
(SUS430BA) belt-shaped member 308 (width 120 m)
mx 200m length x 0.13mm thickness)
The bobbin 317 is set, and the belt-shaped member 308 is
Gate 306, layer forming vacuum vessel 302, 303, 304
, A vacuum container 30 having a belt-like member winding mechanism
5 and the tension was adjusted so that there was no slack. One
Then, vacuum containers 301, 302, 303, 304, 30
5 is 1 × 10 with a vacuum pump (not shown)^-FourUp to Torr
Vacuum was applied. Next, each gate is connected to the gas gate 306.
H as a gate gas from the gas introduction pipe 314_Two70 gas
0 sccm and flow into each vacuum vessel 302, 303, 304
Here, the band member 308 is formed by the lamp heater 309.
Was heated to 350 ° C., 350 ° C., and 300 ° C., respectively. So
Then, the first conductive layer is formed through each gas introduction pipe 212.
Vacuum container 302 contains SiH_Four60 sccm of gas,
P H_Three/ H_Two(= 2%) gas at 50 sccm and H_Two
A gas is introduced at 500 sccm, and the i-type layer forming vacuum vessel 3 is introduced.
03 contains SiH_FourGas at 100 sccm and H_Twogas
Is introduced at 200 sccm to form a second conductive layer forming vacuum container.
304 has SiH_Four20 sccm gas, BF_Three/ H_Two
(= 2%) gas at 100 sccm and H_Two20 gas
00 sccm was introduced. The pressure in the vacuum vessel 301 is
Conductor so that it becomes 1.0 Torr with force meter 316
It was adjusted by the valve 320. Pressure in vacuum vessel 302
Is not shown so that it becomes 1.5 Torr with the pressure gauge 316
Was adjusted by the conductance valve. Inside the vacuum vessel 303
Pressure becomes 0.02 Torr with the pressure gauge 316
Was adjusted by a conductance valve (not shown). Vacuum container
The pressure in 304 reaches 1.6 Torr with pressure gauge 316.
Was adjusted with a conductance valve not shown. true
The pressure in the empty container 305 is 1.0 Torr by the pressure gauge 316.
and adjust it with conductance valve 320
Was. Thereafter, the gas inside the first conductive layer forming vacuum vessel 302 is removed.
400 W of RF power is introduced to the sword electrode 312, and the i-type
In the microwave discharge furnace 331 in the layer forming vacuum vessel 303
200W microwave and 400W RF bias power
And the cathode in the second conductive layer forming vacuum vessel 304.
RF power of 800 W was introduced to the electrode 312. like this
Then, the belt-shaped member 308 is transported in the direction of the arrow in the figure.
On the other hand, the first conductive layer is placed on the
2, the i-type layer is vacuumed in the vacuum vessel 303, and the second conductive layer is vacuumed.
Formed in container 304. Bobbin 31 in vacuum container 305
The belt-shaped member wound on 8 is removed from the plasma CVD device.
I took it out. A transparent electrode is formed on the second conductive layer on the belt-shaped member.
As a pole, an 80 nm thick ITO (In_TwoO_Three+ SnO_Two)
A film is formed by a known vacuum deposition method, and then a collecting electrode
A 2 μm-thick grid electrode made of Al is known in the art.
It was formed by a vacuum deposition method. Thus single Celta
Thus, a photovoltaic element of type I (element-actual 1) was obtained. The photovoltaic
The force element has the configuration shown in FIG. Figure 5
4001 is a substrate (base), 4002 is a back reflection layer,
4003 is a reflection enhancement layer, and 4004 is a first conductive layer (n-type).
Semiconductor layer), 4005 is an i-type layer (i-type semiconductor layer), 40
06 is a second conductive layer (p-type semiconductor layer), 4007 is transparent
An electrode 4008 indicates a collecting electrode.

[0014]

COMPARATIVE EXAMPLE 1 A rod-shaped RF bias power applying electrode as shown in FIG. 3 was used, and the ratio of the surface area of the bias power applying electrode to the entire grounded anode area including the conductive strip was 0.5 times. A microwave discharge furnace having a bias power application electrode structure was fabricated. The microwave discharge furnace was installed in a roll-to-roll type plasma CVD shown in FIG. 4 as a bias power application electrode of the microwave discharge furnace 331 in the vacuum vessel 303 for forming the i-type layer. Except for the above, a single-cell type photovoltaic device (element-ratio 1) having the configuration shown in FIG.

[0015]

[Evaluation] For the photovoltaic element obtained in Example 1 (element-actual 1) and the photovoltaic element obtained in comparative example 1 (element-ratio 1), photoelectric conversion efficiency, uniformity of characteristics, and The yield was evaluated by the evaluation method described below. The obtained evaluation results are summarized in Table 2.

[Evaluation of Photoelectric Conversion Efficiency] Each of element-actual 1 and element-ratio 1 was cut out at an area of 5 cm square at intervals of 10 m.
The device was placed under -1.5 (100 mW / cm ² ) light irradiation, and the photoelectric conversion efficiency was measured. Table 2 shows the obtained results. The values shown in Table 2 are relative values when the photoelectric conversion efficiency of the element-ratio 1 is 1.00.

[Evaluation of uniformity of characteristics] Each of element-actual 1 and element-ratio 1 was cut out at an area of 5 cm square at intervals of 10 m, and AM
The device was placed under -1.5 (100 mW / cm ² ) light irradiation, the photoelectric conversion efficiency was measured, and the variation in the photoelectric conversion efficiency was evaluated. Table 2 shows the evaluation results obtained by calculating the reciprocal of the magnitude of the variation based on the results obtained for the element-ratio 1.

[Evaluation of yield] Each of element-actual 1 and element-ratio 1 was cut out at an area of 5 cm square every 10 m, and the shunt resistance in a dark state was measured. The resistance value was 1 × 10 ³ Ω · cm ² or more. Were counted as non-defective products, and the ratio of the total number was expressed as a percentage and evaluated. Table 2 shows the obtained results. The values shown in Table 2 are relative values when the value for element-ratio 1 is 1.00. From the results shown in Table 2, the element-actual 1
Indicates that the photoelectric conversion efficiency is 1.09 times, the variation of the photoelectric conversion efficiency is 1.14 times, and the yield is 1.26 times, which is excellent in any of the evaluation items as compared with the element-ratio 1. Was. As a result, it has been proved that the present invention makes it possible to mass-produce photovoltaic elements excellent in photoelectric conversion efficiency, uniformity of characteristics, and yield with high productivity.

[0016]

Example 2 (Study of Bias Power Applied Electrode Area) Vacuum container 203 for forming an i-type layer of the plasma CVD apparatus shown in FIG.
Using the box-shaped bias power applying electrode according to the present invention as shown in FIG. 2A as the bias power applying electrode of the microwave discharge furnace 331 in the inside, the ratio of the surface area of the box-shaped bias power applying electrode to the anode electrode surface area is expressed as follows. By changing the height 11 of the box-shaped bias power applying electrode (see FIG. 2A), the height was changed from 0.8 times to 2.6 times as shown in Table 3. In each case, a single-cell type photovoltaic element having the configuration shown in FIG. 5 was produced under the same procedure and film forming conditions as in Example 1. Thus, five photovoltaic elements (element-actual 2 to element-actual 6)
I got The obtained photovoltaic element (element-element 2 to element-
For each of 6), the photoelectric conversion efficiency, the uniformity of the characteristics, and the yield were performed in the same manner as in Example 1. Table 3 summarizes the obtained evaluation results. Table 3 also shows the evaluation results of Example 1 (Element-Comparative 1) and Comparative Example 1 (Element-Comparative 1) for comparison. Each value shown in Table 3 is a relative value when each characteristic of the element-ratio 1 is 1.00. As is evident from the results shown in Table 3, when the ratio of the surface area of the bias power application electrode to the anode electrode becomes large and the value exceeds about 1, that is, the element-actual 6 and the comparative example 1 (element -Compared to the photovoltaic element of ratio 1), the photovoltaic elements of Example 1 (element-actual 1) and element-actual 2 to element-actual 5 and 5 Excellent in all yields. As a result, it has been proved that the present invention makes it possible to mass-produce a photovoltaic element having excellent photoelectric conversion efficiency, uniformity of characteristics, and yield with high productivity.

[0017]

Embodiment 3 (Examination of distance between back surface of bias power applying electrode and anode electrode) The bias power applying electrode of the microwave discharge furnace 331 in the i-type layer forming vacuum vessel 203 of the plasma CVD apparatus shown in FIG. Using the box-shaped bias power applying electrode shown in FIG. 2A, the ratio of the surface area of the box-shaped bias power applying electrode to the anode electrode surface area is fixed to approximately 2.2 times, and the back surface of the bias power applying electrode and the anode electrode are fixed. As shown in Table 4, the gap distance l2 (see FIG. 1A and FIG.
It varied between 0 cm. In each case, a single-cell type photovoltaic element having the configuration shown in FIG. 5 was produced under the same procedure and film forming conditions as in Example 1. Thus, six photovoltaic elements (element-actual 7 to element-actual 12) were obtained. The obtained photovoltaic element (element-real 7
12), the photoelectric conversion efficiency, the uniformity of the characteristics, and the yield were performed in the same manner as in Example 1. Table 4 summarizes the obtained evaluation results. Table 4 also shows the evaluation results of Comparative Example 1 (element-ratio 1) for comparison. Each value in Table 4 is a relative value when each characteristic of the element-ratio 1 is 1.00. As is clear from the results shown in Table 4, the gap distance l2 between the front and back surfaces of the box-shaped bias power application electrode and the anode electrode is approximately 5 mm.
In the following regions, discharge did not occur in the gaps, and stable microwave discharge was obtained only in the discharge furnace. Further, under the condition that the microwave discharge furnace has a structure in which the ratio of the surface area of the box-shaped bias power application electrode to the anode electrode is large and the discharge does not occur in the gap between the front and back surfaces of the box-shaped bias power application electrode and the anode electrode. The manufactured photovoltaic elements, that is, the four photovoltaic elements of element-real 7 to element-real 10 are photovoltaic elements manufactured under conditions other than the above conditions, that is, element-real 11
In addition, it was found that the photoelectric conversion element, the uniformity of characteristics, and the yield were all superior to the photovoltaic element of Element-Ex. As a result, it has been proved that the present invention makes it possible to mass-produce photovoltaic elements excellent in photoelectric conversion efficiency, uniformity of characteristics, and yield with high productivity.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

As described above, the film forming method and apparatus of the present invention using the above-mentioned specific box-shaped bias power applying electrode have high quality, excellent uniformity over a large area, and have a defect. It is possible to efficiently form a functional deposited film with a small number of photovoltaic elements, and to produce a large number of photovoltaic elements having excellent photovoltaic element characteristics with high throughput and high reproducibility.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a microwave discharge furnace in a plasma CVD apparatus using a box-shaped bias power application electrode according to the present invention. (A) is a schematic perspective view, (b)
Is a view from above.

FIG. 2 is a schematic view conceptually showing four examples of a box-shaped bias power application electrode of the present invention.

FIG. 3 is a schematic diagram showing an example of a microwave discharge space in a conventional plasma CVD apparatus using a rod-shaped bias power application electrode. (A) is a perspective view, (b) is a figure seen from above.

FIG. 4 shows a case where the box-shaped bias power applying electrode of the present invention is used.
It is a schematic diagram which shows an example of the plasma CVD apparatus of a roll-to-roll system suitable for manufacture of a photovoltaic element.

FIG. 5 is a schematic sectional view of an example of a single cell type photovoltaic element.

[Explanation of symbols]

 1001, 2001 Microwave applicator 1002, 2002 Microwave fin window 1003, 2003 Microwave discharge furnace 1004, 2004 Band member 1005 Box-shaped bias power application electrode with slit 1006, 2006 Gas manifold 1007, 2007 Reaction vessel wall 1008 Slit shape Hole 2005 Bar-shaped bias power application electrode 301, 302, 303, 304, 305 Vacuum container 306 Gas gate 308 Band member 309 Lamp heater 311 Exhaust port 312 Gas inlet pipe 314 Gate gas inlet pipe 315 Exhaust port 316 Vacuum gauge 317 Delivery bobbin 318 Winding bobbin 320 Conductance valve 321,322 Steering roller 330 Microwave waveguide 331 Discharge furnace vessel

Claims (10)

[Claims] 1. A raw material gas is introduced into a reaction vessel having a discharge space, microwave power is simultaneously introduced into the discharge space, and bias power is applied into the discharge space.
In the method of forming a deposition film on a film-shaped substrate that continuously decomposes and decomposes the source gas by generating a plasma discharge, the bias power is applied, and the surface area in the discharge space is the band shape. A method for forming a deposited film, wherein the method is performed through an electrode having a shape and structure larger than the surface area of the entire anode (ground) electrode including the surface area of the substrate in the discharge space. 2. The electrode for applying the bias power has a structure such that no discharge occurs on the back side of the electrode opposite to the discharge space.
5. The method for forming a deposited film according to item 1. 3. The deposited film according to claim 1, wherein the electrode for applying the bias power has a structure that surrounds the outer periphery of the discharge space and wraps around the entire discharge space. Forming method. 4. The method according to claim 1, wherein the electrode for applying the bias power has a structure that does not hinder the propagation of the microwave into the discharge space. 5. The method according to claim 1, wherein the electrode for applying the bias power has a structure that does not hinder the flow of the introduced source gas and the exhausted gas. 6. A reaction vessel having a discharge space for forming a film on a continuously moving strip-shaped substrate and continuously moving the strip-shaped substrate while exposing a film-forming surface of the strip-shaped substrate to the discharge space. Means for introducing microwave power into the discharge space, source gas introducing means for introducing a source gas into the discharge space, and the discharge vessel. A bias power application electrode for applying bias power to the space, and an exhaust unit for exhausting the inside of the reaction vessel, and microwaves are simultaneously introduced into the discharge space by the source gas introduction unit when the source gas is introduced into the discharge space; Power and bias power are introduced into the discharge space by the microwave introduction means and the bias power application electrode, respectively, to generate plasma discharge, thereby separating the source gas. In the deposited film forming apparatus for forming a deposited film on the strip-shaped substrate that moves continuously, the bias power application electrode may be configured such that a surface area in the discharge space includes an entire anode (ground) electrode including a surface area of the strip-shaped substrate. An electrode having a shape and a structure larger than the surface area in the discharge space. 7. The deposited film according to claim 6, wherein the electrode for applying the bias power has a structure such that no discharge occurs on the back side of the electrode opposite to the discharge space. Forming equipment. 8. The deposited film according to claim 6, wherein the electrode for applying the bias power has a structure surrounding an outer periphery of the discharge space and surrounding the entire discharge space. Forming equipment. 9. The deposition film forming apparatus according to claim 6, wherein the electrode for applying the bias power has a structure that does not hinder the propagation of the microwave into the discharge space. 10. The electrode for applying the bias power has a structure that does not hinder the flow of the source gas introduced into the discharge space and the gas exhausted from the reaction vessel. 7. The deposited film forming apparatus according to 6.