JP2007184505A - Method for manufacturing silicon system thin film photoelectric converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a silicon system thin film photoelectric converter which fabricates at least one or more amorphous photoelectric conversion units or crystalline photoelectric conversion units, so as to improve the efficiency of the silicon system thin film photoelectric converter. <P>SOLUTION: The method for manufacturing the silicon system thin film photoelectric converter includes generating plasma uniformly within a space between a high frequency electrode (A) and a holder (C), even when E/S (the distance of the high frequency electrode and a substrate face) is narrow. To be more precise, using a plasma CVD equipment including at least the high frequency electrode (A), a substrate (B), and the holder (C), the plasma CVD method is carried out to arrange on a roughly same flat plane a film deposition plane (i) of the substrate face facing the high frequency electrode of the substrate (B); and a plane (ii) which consists of a part of the holder (C) and faces to the high frequency electrode nearest to the end of the substrate which is in parallel direction to the film deposition plane, and nearest to the high frequency electrode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is characterized by producing at least one amorphous silicon photoelectric conversion unit including an amorphous silicon photoelectric conversion layer or at least one crystalline silicon photoelectric conversion unit including a crystalline silicon photoelectric conversion layer. The present invention relates to a method for manufacturing a thin film photoelectric conversion device.

  In recent years, a thin film photoelectric conversion device that requires less raw materials in order to achieve both cost reduction and high efficiency of a photoelectric conversion device including a solar cell has attracted attention and has been vigorously developed. In particular, a method of forming a high-quality semiconductor layer on an inexpensive substrate such as glass using a low-temperature process is expected as a method capable of realizing low cost.

  Such a thin film photoelectric conversion device generally includes a transparent electrode layer, one or more photoelectric conversion units, and a back electrode layer that are sequentially stacked on an insulating translucent substrate. Here, the photoelectric conversion unit generally has a p-type layer, an i-type layer, and an n-type layer laminated in this order or vice versa, and the i-type photoelectric conversion layer occupying the main part is amorphous. Is called an amorphous photoelectric conversion unit, and those having an i-type layer crystalline are called crystalline photoelectric conversion units.

  In order to effectively confine light incident from the translucent substrate side in the photoelectric conversion unit, the transparent conductive film usually has many fine irregularities formed on the surface, and the height difference is generally It is about 0.05 μm to 0.3 μm. There is a haze ratio as an index representing the degree of unevenness of the transparent conductive film. This is equivalent to the light that is transmitted when the light from a specific light source is incident on a transparent substrate with a transparent conductive film divided by the scattered component whose optical path is bent and divided by all components. Measured using a C light source containing In general, the haze ratio increases as the height difference between the projections and depressions increases, or as the interval between the projections and depressions of the projections and projections increases, so that the light incident on the photoelectric conversion unit is effectively confined.

  The i-type layer is a substantially intrinsic semiconductor layer and occupies most of the thickness of the photoelectric conversion unit, and the photoelectric conversion action mainly occurs in the i-type layer. For this reason, this i-type layer is usually called an i-type photoelectric conversion layer or simply a photoelectric conversion layer. The photoelectric conversion layer is not limited to an intrinsic semiconductor layer, and may be a layer doped in a small amount of p-type or n-type within a range where loss of light absorbed by a doped impurity (dopant) does not become a problem. The photoelectric conversion layer is preferably thicker for light absorption, but if it is thicker than necessary, the cost and time for film formation will increase.

  On the other hand, the p-type or n-type conductive semiconductor layer plays a role of generating an internal electric field in the photoelectric conversion unit, and an open-circuit voltage (one of important characteristics of the thin film photoelectric conversion device depending on the magnitude of the internal electric field). The value of Voc) is influenced. However, these conductive semiconductor layers are inactive layers that do not directly contribute to photoelectric conversion, and light absorbed by impurities doped in the conductive semiconductor layer is a loss that does not contribute to power generation. Therefore, it is preferable that the p-type and n-type conductive semiconductor layers have a thickness as small as possible as long as a sufficient internal electric field can be generated. The thickness of the conductive semiconductor layer is generally about 20 nm or less.

  As a method for improving the conversion efficiency (Eff) of the thin film photoelectric conversion device, there is a method of stacking two or more photoelectric conversion units. In this case, by arranging a front unit including a photoelectric conversion layer having a large band gap on the light incident side of the thin film photoelectric conversion device, and arranging a rear unit including a photoelectric conversion layer having a small band gap in order behind the unit. Photoelectric conversion is enabled over a wide wavelength range of incident light, thereby improving the conversion efficiency of the thin film photoelectric conversion device as a whole. Among such stacked thin film photoelectric conversion devices, in particular, an amorphous silicon photoelectric conversion unit and a crystalline silicon photoelectric conversion unit that are stacked one by one and electrically connected in series are silicon-based hybrid thin film photoelectric conversion devices. Called.

  For example, the wavelength of light that can be photoelectrically converted by i-type amorphous silicon is up to about 800 nm on the long wavelength side, but i-type crystalline silicon photoelectrically converts light up to a wavelength of about 1150 nm longer than that. Can do.

  Among the output characteristics of the silicon-based hybrid thin film photoelectric conversion device, the short-circuit current density (Jsc) is the spectral sensitivity integral current (spectrum) of the amorphous silicon photoelectric conversion unit (hereinafter simply referred to as the top cell) disposed in front. Sensitivity is measured, and the solar spectrum intensity represented by air mass 1.5 is multiplied by each wavelength and integrated to calculate the output current density) and the crystalline silicon photoelectric conversion unit (hereinafter referred to as this) It is determined by the magnitude relationship with the spectral sensitivity integral current (simply referred to as the bottom cell). Specifically, if the spectral sensitivity integrated current of the bottom cell is larger than the spectral sensitivity integrated current of the top cell, Jsc of the entire silicon-based hybrid thin film photoelectric conversion device is limited by the spectral sensitivity integrated current of the top cell. Conversely, if the spectral sensitivity integrated current of the bottom cell is smaller, the overall Jsc is limited by the spectral sensitivity integrated current of the bottom cell.

In general, in a crystalline thin film photoelectric conversion unit using crystalline silicon for an i-type layer, there is a method of increasing the hydrogen dilution rate of the i layer in order to increase the crystalline silicon crystal grains and improve the crystal fraction. It is known (Non-Patent Document 1). The crystal fraction here is defined as (volume of crystal grains) / (total volume), and the hydrogen dilution rate is defined as (H ₂ gas flow rate) / (SiH ₄ gas flow rate). Conversely, it is generally known that when the hydrogen dilution rate of the i layer is lowered, the amorphous component is increased and the crystal fraction is lowered. It is also known that when the crystal fraction of the i-layer crystalline silicon is high, Voc is lowered and Jsc is improved, and when the crystal fraction is low, Voc is improved and Jsc is lowered (Non-patent Document 2). That is, by using a method of finely adjusting the crystal fraction of the crystalline thin film photoelectric conversion unit with the hydrogen dilution rate, the voltage can be improved while maintaining a high current.

  When manufacturing such a silicon-based thin film photoelectric conversion device as a large-area silicon-based thin film photoelectric conversion device capable of generating high output at a high voltage for power, a silicon-based thin film photoelectric conversion device formed on a large substrate is used. Rather than using a plurality of units connected in series, a silicon-based thin film photoelectric conversion device formed on a large substrate is divided into a plurality of cells to improve yield, and these cells are connected in series and integrated. Is common. In particular, in a silicon-based thin-film photoelectric conversion device in which light is incident from the glass substrate side using a glass plate as the substrate, the resistance of the transparent electrode layer on the glass substrate is formed after sequentially forming the semiconductor layer on the glass substrate. In order to reduce loss due to laser, a separation groove for processing the transparent electrode into a strip having a predetermined width is provided by a laser scribing method, and the cells are connected in series in a direction perpendicular to the longitudinal direction of the strip to integrate the cells. (Hereinafter, the silicon-based thin film photoelectric conversion device integrated as described above is referred to as a silicon-based thin film photoelectric conversion module). Since each strip-shaped cell is connected in series, Jsc of the silicon-based thin film photoelectric conversion module is limited to the smallest value among the current values generated in each cell. Therefore, the current value of each cell is preferably as uniform as possible, and the Eff of the silicon-based thin film photoelectric conversion module can be expected to increase as the absolute value of the current increases.

  By the way, there are various types of apparatuses for depositing the above-mentioned amorphous silicon or crystalline silicon on a substrate, but a plasma is generated in a container into which a source gas is introduced to generate free radicals and the like. Plasma CVD apparatuses that form a film by depositing active species on a substrate can be broadly classified into capacitively coupled plasma CVD apparatuses and inductively coupled plasma CVD apparatuses according to plasma generation methods. In general, since the capacitively coupled plasma CVD apparatus can easily obtain a uniform discharge with respect to a large area substrate, it is used for film formation of a large area substrate such as a liquid crystal display or a solar cell. Inductively coupled plasma CVD devices tend to be used for etching because they tend to generate high-density plasma. The plasma CVD apparatus can be roughly divided into two types depending on whether or not a holder for transporting the substrate is required.

  The inside of a capacitively coupled plasma CVD apparatus having a substrate transfer holder includes a high frequency electrode called a shower plate having many holes with a diameter of about 0.2 to 1 mm, and a substrate and a substrate facing each other. Generally, it is composed of a holder for holding. FIG. 3 shows a schematic cross-sectional view of a general substrate transport holder. The holder 10 includes an outer frame 13 made of stainless steel or aluminum having an inner shape slightly larger than the outer shape of the substrate 11, and the outer frame 13 is provided with a stepped portion 14 that supports the surface of the substrate 11 with a constant thickness. It has been. When the holder 10 is used, the substrate 11 is installed on the stepped portion 14, and the pressing plate 12 is installed on the substrate to support the back surface of the substrate 11. The surface of the substrate 11 opposite to the holding plate 12 side is open and serves as a substrate film-forming surface 7. Further, in order to hold the pressing plate 12 on the outer frame 13, for example, the fixing member 15 is fixed to the outer frame with screws so as to hold the pressing plate 12.

  Further, there is a structural example described in Patent Document 1 as a patent for a holder that can greatly reduce the man-hours required for changing the substrate size and can be easily replaced at low cost.

  FIG. 4 shows a schematic cross-sectional view of the holder described in Patent Document 1. It consists of a stainless steel or aluminum rectangular outer frame 13 having an opening having an inner shape slightly larger than the outer shape of the maximum size glass substrate, and an auxiliary frame member 16 that can be removed from the outer frame 13. A step portion 14 for supporting a substrate of the maximum size is provided with a constant thickness over the entire inner periphery of the opening of the outer frame 13. On the other hand, the auxiliary frame member 16 is also provided with an auxiliary frame member step 17 for supporting the substrate with a certain thickness, and supports the single or plural substrates 11 within the range of the size of the auxiliary frame member 16. be able to.

Furthermore, in order to improve the crystalline silicon film quality of the crystalline thin film photoelectric conversion unit using crystalline silicon for the i-type layer, it is better to form the film with the distance between the high-frequency electrode and the substrate as narrow as possible. It is generally known. This can be considered that since the plasma region where radicals are generated approaches the substrate, hydrogen radicals with severe losses effectively reach the film, and the film quality is improved.
Japanese Patent Application No. 09-192604. T. Roschek, T. Repmann, J. Muller, B. Rech, H. Wagner: Proceedings of the 28th IEEE Photovoltaic Specialists Conference, Anchorage, 2000, pp. 150-153. T. Repmann, W. Appenzeller, T. Roschek, B. Rech, H. Wagner: Proceedings of the 28th IEEE Photovoltaic Specialists Conference, Anchorage, 2000, pp.912-915.

<Analysis of points that require improvement in the prior art>
However, since the holder 10 described above absolutely requires the step portion 14 or the step portion 17 for supporting the outer edge of the substrate 11 in the thickness direction, the step portion 14 or the step portion 17 where the holder 10 supports the substrate 11. The substrate film-forming surface 7 and the holder surface 8 are stepped by the thickness of the substrate, and the substrate film-forming surface 7 and the holder surface 8 are not arranged in substantially the same plane. In other words, the substrate 11 has a holder 10 like a frame. (Hereinafter, this holder is referred to as a frame holder). Here, “arranged in substantially the same plane” means a state in which the plane and the plane are arranged at an interval within ± 1 mm.

  Since the frame holder has a step between the substrate film-forming surface 7 and the holder surface 8 as described above, the distance between the high-frequency electrode and the holder surface 8 (hereinafter referred to as E / H), the high-frequency electrode and the substrate film-forming surface. 7 (hereinafter referred to as E / S) is different. For this reason, plasma is not uniformly generated in the space between the high-frequency electrode and the holder surface 8 in a portion where there is a step around the substrate film forming surface 7, and the film thickness and film quality around the substrate 7 are not uniform. It was easy to be. In other words, silicon-based thin-film photoelectric conversion modules formed using conventional frame holders can be integrated even if the film fraction is fine-tuned with the hydrogen dilution rate to improve the voltage while maintaining a high current. Since the current value of each strip-shaped cell is limited where the film thickness and film quality around the substrate are not uniform, the high current and high voltage cannot be achieved at the same time, and Eff does not improve. There was a problem.

  Further, in order to improve the film quality, the dissociation ratio of E / S and E / H increases as the film forming conditions of E / S are narrow, and plasma is generated only at a part between the high-frequency electrode and the holder 10. There was a trend. That is, even in a narrow region where E / S is 8 mm or less, it is difficult to form a film on the entire surface of the substrate.

<Setting new issues>
In view of the situation as described above, the present invention provides at least the high-frequency electrode that can generate plasma uniformly in the space between the high-frequency electrode (A) and the holder (C) even when the E / S is narrow. A), an amorphous photoelectric conversion unit including an amorphous silicon photoelectric conversion layer, or a crystalline material including a crystalline silicon photoelectric conversion layer using a plasma CVD apparatus including the substrate (B) and the holder (C) An object of the present invention is to manufacture a silicon-based thin film photoelectric conversion device characterized by producing at least one photoelectric conversion unit and to improve the conversion efficiency of the silicon-based thin film photoelectric conversion device.

(1) The first of the present invention is
"at least,
(A) a high-frequency electrode;
(B) a substrate disposed opposite to the high-frequency electrode;
(C) A method of manufacturing a silicon-based thin film photoelectric conversion device including a plasma CVD process using a plasma CVD device that is disposed to face the high-frequency electrode and includes a holder that holds the substrate. (I) and (ii) are performed by plasma CVD performed in the arrangement state of (iii),
Production of a silicon-based thin film photoelectric conversion device, comprising at least one amorphous photoelectric conversion unit including an amorphous silicon photoelectric conversion layer or at least one crystalline photoelectric conversion unit including a crystalline silicon photoelectric conversion layer Method.
(I) A film-forming surface that is a substrate surface facing the high-frequency electrode of the substrate (B).
(Ii) a surface that forms part of the holder (C) and faces the high-frequency electrode;
A surface closest to the substrate end in a direction parallel to the film forming surface and closest to the high-frequency electrode.
(Iii) The state arrange | positioned on the substantially the same plane. "
.

(2) The second aspect of the present invention is
The silicon-based thin film photoelectric conversion according to (1), wherein the holder (C) has means for holding (B) from the side surface with respect to the film-forming surface of the substrate (B). Device manufacturing method "
.

(3) The third aspect of the present invention is
“The shortest distance between the film-forming surface that is the substrate surface facing the high-frequency electrode of the substrate (B) and the main surface of the high-frequency electrode (A) is greater than 0 mm and 8 mm or less. Manufacturing method of silicon-based thin film photoelectric conversion device according to (1) or (2) "
.

  According to the present invention, even when the E / S is narrow, plasma is more uniformly generated in the space between the high frequency electrode (A) and the holder (C) as compared with the conventional manufacturing method using the frame holder. Since it can be generated, the uniformity of film thickness and film quality formed on the substrate (B) and the film quality are improved, and an amorphous photoelectric conversion unit including an amorphous silicon photoelectric conversion layer, or crystalline silicon Eff of a silicon-based thin film photoelectric conversion device characterized by producing at least one crystalline photoelectric conversion unit including a photoelectric conversion layer can be improved. Moreover, even if the E / S is so narrow that abnormal discharge may occur in the conventional frame holder, the silicon-based photoelectric conversion device can be manufactured without abnormal discharge.

  In the present invention, since the plasma can be generated more uniformly in the space between the high-frequency electrode (A) and the holder (C) even when the E / S is narrow, a conventional frame holder is used. Compared with the manufacturing method used, the film thickness and film quality uniformity formed on the substrate (B) are improved, and the Jsc of the silicon-based thin film photoelectric conversion module is improved. In addition, even with a low hydrogen dilution rate in which a non-uniform portion of film thickness and film quality is generated in the conventional frame holder, the film thickness and film quality are not non-uniform, and the Voc of the silicon-based thin film photoelectric conversion module is improved. I also found out. Therefore, Jsc and Voc of the silicon-based thin film photoelectric conversion module are improved, and Eff is improved.

  In the present invention, since the plasma can be generated more uniformly in the space between the high-frequency electrode (A) and the holder (C) even when the E / S is narrow, a conventional frame holder is used. It has been found that the uniformity of the film thickness and film quality formed on the substrate (B) is improved and the Jsc of the silicon-based thin film photoelectric conversion device is improved as compared with the manufacturing method used. In addition, even with a low hydrogen dilution rate in which a non-uniform portion of film thickness and film quality is generated in the conventional frame holder, the film thickness and film quality are not non-uniform, and the Voc of the silicon-based thin film photoelectric conversion module is improved. I also found out. Therefore, it was found that Jsc and Voc of the silicon-based thin film photoelectric conversion module are improved and Eff is improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings and tables. In each drawing of the present application, dimensional relationships such as thickness and length are appropriately changed for clarity and simplification of the drawings, and do not represent actual dimensional relationships. Moreover, in each figure, the same referential mark represents the same part or an equivalent part.

Below, the manufacturing method of the silicon type hybrid thin film photoelectric conversion apparatus as embodiment of this invention is demonstrated, referring FIG. Here, as one embodiment of the present invention, an example in which a crystalline photoelectric conversion unit is formed following an amorphous photoelectric conversion unit will be described as an example. However, the present invention is not limited to this example. A transparent conductive film 2 is formed on the translucent substrate 1. As the translucent substrate 1, a plate-like member or a sheet-like member made of glass, transparent resin, or the like can be used.

  As the transparent conductive film 2, a metal oxide such as tin oxide or zinc oxide can be used. The transparent conductive film 2 can be formed using a method such as CVD, sputtering, or vapor deposition. The transparent conductive film 2 has the effect of increasing the scattering of incident light by producing fine irregularities on the surface by devising the formation conditions. The height difference of the unevenness is about 0.05 to 0.3 μm, and the sheet resistance can be set to about 5 to 20 Ω / □.

As one embodiment of the present invention, an amorphous photoelectric conversion unit 3 that is a top cell is formed on the transparent conductive film 2. As one aspect of the amorphous photoelectric conversion unit 3, the amorphous photoelectric conversion unit 3 includes an amorphous p-type silicon carbide layer 3p, a non-doped amorphous i-type silicon photoelectric conversion layer 3i, and an n-type silicon layer 3n. The material of the non-doped amorphous i-type silicon photoelectric conversion layer 3i may be not only silicon but also an alloy such as silicon carbide or silicon germanium.
Further, instead of the n-type silicon layer 3n, in order to reflect the light that has not been absorbed by the amorphous i-type silicon photoelectric conversion layer 3i and has passed backwards again to the amorphous i-type silicon photoelectric conversion layer 3i side, A low refractive index layer such as silicon oxide containing microcrystalline silicon may be disposed.

  As one aspect of the present invention, a crystalline photoelectric conversion unit 4 that is a bottom cell is formed on an amorphous photoelectric conversion unit 3. The crystalline photoelectric conversion unit 4 includes a crystalline p-type silicon layer 4p, a crystalline i-type silicon photoelectric conversion layer 4i, and a crystalline n-type silicon layer 4n. Instead of the crystalline n-type silicon layer 4n, a long wavelength light that could not be absorbed by the bottom cell by using a laminate of a low refractive index layer such as silicon oxide containing microcrystalline silicon and a crystalline n-type silicon layer. May be effectively reflected again to the bottom cell side.

  Note that the amorphous or crystalline silicon-based material is not only a case where only silicon is used as a main element constituting a semiconductor, but also an alloy material including elements such as carbon, oxygen, nitrogen, and germanium. Good. The main constituent material of the conductive layer is not necessarily the same as that of the i-type layer. For example, amorphous silicon carbide can be used for the p-type layer of the amorphous silicon photoelectric conversion unit, and n A silicon layer (also referred to as μc-Si) containing crystal in the mold layer can also be used.

The plasma CVD method described later is suitable for forming the amorphous photoelectric conversion unit 3 and the crystalline photoelectric conversion unit 4 (hereinafter, both units are collectively referred to as a photoelectric conversion unit). As conditions for forming the photoelectric conversion unit, a substrate temperature of 100 to 250 ° C., a pressure of 30 to 3000 Pa, a high frequency power density of 0.01 to 0.5 W / cm ² , and an E / S of 30 mm or less are preferably used. In particular, the crystalline i-type silicon photoelectric conversion layer 4i has a crystal fraction of 3 to 7, a hydrogen dilution rate of 100 to 250, a pressure of 800 Pa to 3000 Pa, a high frequency power density of 0.05 to 0.2 W / cm ² , E More preferably, the film is formed at / S = 8 mm or less. As a source gas used for forming the photoelectric conversion unit, a silicon-containing gas such as SiH ₄ or Si ₂ H ₆ or a mixture of these gases and hydrogen is used. B ₂ H ₆ or PH ₃ is preferably used as the dopant gas for forming the p-type or n-type layer in the photoelectric conversion unit.

  Alternatively, after the n-type silicon layer 3n of the amorphous photoelectric conversion unit 3 is formed, the substrate is once taken out into the atmosphere, and the crystalline photoelectric conversion unit 4 is formed again by another plasma CVD apparatus. However, in that case, it is preferable to form the n-type silicon layer 3n again before forming the crystalline p-type silicon layer 4p of the crystalline photoelectric conversion unit 4.

  Further, the n-type silicon layer 3n to be formed again, the crystalline p-type silicon layer 4p of the crystalline photoelectric conversion unit 4, the crystalline i-type silicon photoelectric conversion layer 4i, and the crystalline n-type silicon layer 4n are formed in the same chamber. You may form into a film.

  As one aspect of the present invention, the back electrode layer 5 is formed on the n-type silicon layer 4n. For the back electrode layer 5, Ag, Al, or an alloy thereof is preferably used. A transparent reflective layer 5t may be inserted between the back electrode layer 5 and the n-type silicon layer 4n in order to prevent metal diffusion from the back electrode layer 5 to the n-type silicon layer 4n. For the transparent reflective layer 5t, a metal oxide having low resistance and excellent transparency such as ZnO or ITO is used. In forming the transparent reflective layer 5t and the back electrode layer 5, methods such as sputtering and vapor deposition are preferably used.

(1) The first of the present invention is
"at least,
(A) a high-frequency electrode;
(B) a substrate disposed opposite to the high-frequency electrode;
(C) A method of manufacturing a silicon-based thin film photoelectric conversion device including a plasma CVD process using a plasma CVD device that is disposed to face the high-frequency electrode and includes a holder that holds the substrate. (I) and (ii) are performed by plasma CVD performed in the arrangement state of (iii),
Production of a silicon-based thin film photoelectric conversion device, comprising at least one amorphous photoelectric conversion unit including an amorphous silicon photoelectric conversion layer or at least one crystalline photoelectric conversion unit including a crystalline silicon photoelectric conversion layer Method.
(I) A film-forming surface that is a substrate surface facing the high-frequency electrode of the substrate (B).
(Ii) a surface that forms part of the holder (C) and faces the high-frequency electrode;
A surface closest to the substrate end in a direction parallel to the film forming surface and closest to the high-frequency electrode.
(Iii) The state arrange | positioned on the substantially the same plane. "
.

  In these silicon-based thin film photoelectric conversion devices, the substrate film-forming surface (i) and the holder surface (ii) are disposed on substantially the same plane (iii), and at least the high-frequency electrode (A), the substrate (B), and the holder ( It is preferable to manufacture using a plasma CVD apparatus including C). FIG. 5 shows a schematic cross-sectional view of the holder (C) described above, and FIG. 6 shows a schematic plan view of the holder viewed from the film forming surface. Needless to say, these FIG. 5 and FIG. 6 represent one embodiment of the present invention, and the present invention is not limited to FIG. 5 and FIG.

  The holder 20 shown in FIG. 5 is composed of an outer frame 13 made of stainless steel or aluminum having an inner shape slightly larger than the outer shape of the substrate 11, and a stepped portion for supporting the pressing plate 12 is constant on the outer frame. The thickness is provided. A holding plate 12 is attached to the step portion with a fixing member 15 in advance. When the holder 20 is used, the substrate 11 is installed from the side opposite to the side on which the fixing member 15 is attached, and is fixed from the side surface of the substrate 11 by the substrate fastening member 21. However, the specific means for fixing the substrate 11 from the side surface by the substrate fastening member 21 is not limited as long as the state in which the substrate film-forming surface 7 and the holder surface 8 are arranged on substantially the same plane is not impaired.

  Here, the “state of being arranged in substantially the same plane” means a state in which the plane and the plane are arranged in parallel to the same plane with an interval of ± 1 mm or less.

(2) The second aspect of the present invention is
The silicon-based thin film photoelectric conversion according to (1), wherein the holder (C) has means for holding (B) from the side surface with respect to the film-forming surface of the substrate (B). Device manufacturing method "
.

  In FIG. 6, although the board | substrate fastening member 21 is arrange | positioned at right and left two places, the quantity and arrangement | positioning of the board | substrate fastening member 21 are not limited. For example, the quantity may be larger, and the arrangement may be not only on the left and right but also on the top and bottom. However, it is desirable that the bottom is not disposed because it is fixed by its own weight. The substrate fastening member 21 of FIG. 6 which is one embodiment of the present invention is “means that the holder (C) holds (B) from the side with respect to the film-forming surface of the substrate (B)”. .

  Further, when the substrate 11 is installed on the holder 20, the substrate film-forming surface 7 and the holder surface 8 are arranged on substantially the same plane.

(3) The third aspect of the present invention is
“The shortest distance between the film-forming surface that is the substrate surface facing the high-frequency electrode of the substrate (B) and the main surface of the high-frequency electrode (A) is greater than 0 mm and 8 mm or less. Manufacturing method of silicon-based thin film photoelectric conversion device according to (1) or (2) "
.

  Next, FIG. 8 shows an arrangement example of the high-frequency electrode (A), the substrate (B), and the holder (C). The electrode 30 is generally composed of a stainless steel or aluminum high-frequency electrode 31, a Teflon (registered trademark) surrounding the side surface of the high-frequency electrode 31, a ceramic insulating member 32, and a stainless steel or aluminum earth shield 33. The earth shield 33 suppresses the generation of plasma outside the space between the high frequency electrode 31 and the holder 20. Although the surface of the high-frequency electrode 31 opposite to the substrate 11 is not shown in FIG. 8, another holder 20 may be arranged so that the substrate 11 faces the high-frequency electrode 31. Further, the surface of the high frequency electrode 31 opposite to the substrate 11 may cover the high frequency electrode 31 with an insulating member 32 and a ground shield 33. In FIG. 8, the substrate film-forming surface 7 and the holder surface 8 are arranged on substantially the same plane, and E / S and E / H (the distance between the high-frequency electrode and the holder surface 8 is referred to as E / H, as described above, Since the distance between the electrode and the substrate deposition surface 7 is referred to as E / S.), The plasma can be generated uniformly in the space between the holder 20 and the electrode 30.

9 which is one embodiment of the present invention, the insulating member 32 and the earth shield 33 of the electrode 30 protrude from the high-frequency electrode surface 9 to the holder side. The high-frequency electrode (A), the substrate (B), and the holder (C) This is an arrangement example. In FIG. 9, although the holder 20 has a protrusion of the insulating member 32 and the earth shield 33,
“Similar to FIG. 8, in FIG. 9, the substrate film-forming surface 7 and the holder surface 8 are arranged on substantially the same plane,
(I) a film forming surface which is a substrate surface facing the high frequency electrode of the substrate (B);
Shortest distance E / S with the high-frequency electrode surface 9 which is the “main surface” that is not hidden by the insulating member 32 of the high-frequency electrode (A) ”
And (i) a film-forming surface that is a substrate surface facing the high-frequency electrode of the substrate (B) and (iii) substantially on the same plane,
(Ii) a surface that forms part of the holder (C) and faces the high-frequency electrode;
The surface closest to the substrate edge in the direction parallel to the film-forming surface and closest to the high-frequency electrode, that is, “the surface of the substrate-clamping member 21 disposed on substantially the same plane as the film-forming surface”;
Shortest distance E / H with respect to the high-frequency electrode surface 9 which is a “main surface” that is not hidden by the insulating member 32 of the high-frequency electrode (A) ”
Therefore, the plasma can be generated uniformly in the space between the holder 20 and the electrode 30. In the arrangement example of FIG. 9, the insulating member 32 and the earth shield 33 are drawn so as to protrude to the same extent, but there is no problem even if they are different. In addition, it does not matter if it is retracted instead of protruding. However, the extent to which the earth shield 33 is retracted is limited to such an extent that it does not prevent the plasma from being generated outside the space between the high-frequency electrode 31 and the holder 20.

  As described above, the third “main surface of the high-frequency electrode (A)” of the present invention is a portion that is not hidden by the insulating member 32 as described in 9, for example, the high-frequency electrode surface 9. Of these, the main surface in terms of area (the high-frequency electrode surface 9 having an area of at least more than 50%).

  FIG. 10 which is one embodiment of the present invention is an arrangement example of the high-frequency electrode (A), the substrate (B), and the holder (C) in which the insulating member 34 is attached to the outer frame 13 of the holder 20. In FIG. 10, the insulating member 34 protrudes from the holder 20, but the substrate film-forming surface 7 and the holder surface 8 are arranged on substantially the same plane as in FIG. 8, and the difference between E / S and E / H is the same. Therefore, plasma can be generated uniformly in the space between the holder 20 and the electrode 30. However, if the insulating member 34 is disposed at a location close to the inner side surface of the outer frame 13, the plasma is prevented from being uniformly generated in the space between the holder 20 and the electrode 30 like the frame holder. Therefore, the insulating member 34 can be disposed at a location close to the inner side surface of the outer frame 13 within a range that does not prevent the plasma from being uniformly generated in the space between the holder 20 and the electrode 30. Further, the insulating member 34 can be enlarged as long as it does not interfere with the conveyance of the holder 20 and does not contact the electrode 30 with the aim of confining the plasma in the space between the holder 20 and the electrode 30.

  FIG. 11, which is one embodiment of the present invention, is an arrangement example of the high-frequency electrode (A), the substrate (B), and the holder (C) in which the protruding portion 35 is provided on the high-frequency electrode 31 side of the outer frame 13 of the holder 20. Unlike the insulating member 34 in FIG. 10, the protrusion 35 in FIG. 11 is a conductor, and thus the protrusion 35 generally causes abnormal discharge between the holder 20 and the electrode 30. For this reason, it is preferable that there is no protrusion 35 as much as possible. However, the protrusion 35 can be disposed on the holder 20 as long as it is necessary to transport the holder 20 and is sufficiently away from the electrode 30 to the extent that abnormal discharge does not occur.

  Next, FIG. 13 which is one embodiment of the present invention shows in more detail the schematic structure of the substrate fastening member 21. As shown in FIG. 13, the substrate fastening member 21 of the holder 20 has a structure in which the substrate 11 is held from the side surface of the substrate 11 by using a portion whose corner is cut by the end face processing of the substrate 11. For this reason, the board | substrate film-forming surface 7 and the holder surface 8 can be arrange | positioned on substantially the same plane. In order to prevent the substrate 11 from cracking due to thermal expansion, it is preferable to use a spring so that the substrate fastening member 21 presses the substrate 11 from the side surface.

  The type of the substrate fastening member 21 includes a trapezoidal line contact type substrate fastening member 23 that contacts the substrate 11 with a line as shown in FIG. 13A, and a substrate 11 as shown in FIG. 13B. There is a spindle type point contact type substrate fastening member 24 that contacts at a point. However, since the point contact type substrate fastening member 24 is in contact with the substrate 11 at a point, the line contact type substrate fastening member 23 is in contact with the substrate 11 with a line, whereas the pressing force against the substrate 11 is strong. . For this reason, there is a possibility that the substrate 11 is missing in the point contact type substrate fastening member 24. Accordingly, the substrate contact member 21 is more preferably the line contact substrate stop member 23. The cross section AA in FIG. 13A represents a cross section at AA between the upper left A portion in FIG. 13A and the upper right A portion in FIG. Further, the cross section BB in FIG. 13 (2) represents a cross section at BB between the upper left B portion in FIG. 13 (2) and the upper right B portion in FIG. 13 (2).

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

Example 1
As a silicon-based thin film photoelectric conversion device of Example 1, a silicon-based hybrid thin film photoelectric conversion module was produced. FIG. 2 is a schematic cross-sectional view of the silicon-based thin film photoelectric conversion module.

First, a blue plate glass having a thickness of 910 mm × 455 mm × 4 mm was used as the translucent substrate 1. Next, a transparent conductive film 2 having a fine concavo-convex structure on the surface made of tin oxide was formed on one main surface of the translucent substrate 1 by a thermal CVD method. The obtained transparent conductive film 2 had a thickness of 0.8 μm, a haze ratio of 14%, and a sheet resistance of 12Ω / □. Next, a transparent electrode layer separation groove 2a having a width of 50 μm is formed by irradiating the transparent substrate 1 with a YAG fundamental wave pulse laser in order to divide the transparent conductive film 2 into a plurality of strip patterns. Ultrasonic cleaning and drying were performed.
Furthermore, in order to form the amorphous photoelectric conversion unit 3, the translucent substrate 1 on which the transparent conductive film 2 is formed is introduced into a plasma CVD apparatus using a frame holder for transporting the substrate, and has a thickness of 150 mm. An amorphous p-type silicon carbide (p-type a-SiC) layer 3p was formed. Subsequently, an n-type silicon layer in which a non-doped amorphous i-type silicon photoelectric conversion layer 3i having a thickness of 3300 mm and a low-refractive index layer 600 mm such as silicon oxide containing microcrystalline silicon and an n-type crystalline silicon layer 50 mm are stacked. 3n was laminated sequentially. In the formation of the p-type a-SiC layer 3p, SiH ₄ , hydrogen, B ₂ H ₆ diluted with hydrogen, and CH ₄ were used as reaction gases, and the thickness of the p-type a-SiC layer 3p became 80 mm. While maintaining the discharge at that time, the supply of hydrogen-diluted B ₂ H ₆ and CH ₄ was stopped, and the remaining 70 mm of film was formed.

  Next, in order to form the crystalline photoelectric conversion unit 4, the substrate was once taken out into the atmosphere and another plasma CVD apparatus having a new holder structure was used. FIG. 7 shows a schematic cross-sectional view of the new holder actually used. The holder 20 includes an outer frame 13 made of stainless steel or aluminum having an inner shape slightly larger than the outer shape of the substrate 11, and a stepped portion for supporting the pressing plate 12 is provided on the outer frame with a constant thickness. ing. A holding plate 12 is attached to the step portion with a fixing member 15 in advance. When the holder 20 is used, the substrate 11 is installed from the side opposite to the side on which the fixing member 15 is attached, and is fixed from the side surface of the substrate 11 by the substrate fastening member 21. In this holder, as a means for fastening the substrate 11 from the side surface, a method of attaching a substrate fastening member 21 having an oblique inclination to the holding plate 12 and pressing the substrate 11 from the side surface by a spring 22 and fixing it is used. Since the corners of the end surface of the substrate 11 are generally cut by end surface processing, the inclined portion of the substrate fastening member 21 is caught on the substrate 11, and the substrate 11 is fixed to the pressing plate 12. By fixing the substrate 11 to the outer frame 13 in this manner, the film forming surface of the substrate 11 and the surface on the film forming surface side of the outer frame 13 of the holder 20 are arranged on substantially the same surface. Further, by using the spring 22, substrate cracking due to thermal expansion of the substrate 11 is mitigated. In addition to holding the substrate 11, the pressing plate 12 also plays a role of warming the substrate 11 to a predetermined temperature, and has been subjected to black processing in order to effectively absorb the radiant heat from the heater installed on the pressing plate side. .

  Next, an n-type crystalline silicon layer 3n having a thickness of 100 mm, a p-type crystalline silicon layer 4p having a thickness of 150 mm, a crystalline i-type silicon photoelectric conversion layer 4i having a thickness of 25000 mm, and an n-type crystalline silicon having a thickness of 100 mm Layer 4n was sequentially stacked in the same chamber. The crystalline i-type silicon photoelectric conversion layer 4i was formed with E / S = 6 to 12 mm.

  Next, in order to divide the amorphous photoelectric conversion unit 3 and the crystalline photoelectric conversion unit 4 into a plurality of strip patterns, the substrate is taken out into the atmosphere, and a YAG second harmonic pulse laser is applied to the translucent substrate 1. By irradiation, a connection groove 4a having a width of 60 μm was formed. Thereafter, a transparent reflective layer (not shown) made of 900 mm thick ZnO and a back electrode layer 5 made of 2000 mm thick Ag were formed by DC sputtering.

  Finally, in order to divide the amorphous photoelectric conversion unit 3, the crystalline photoelectric conversion unit 4, and the back electrode layer 5 into a plurality of strip patterns, the YAG second harmonic pulse laser is irradiated to the translucent substrate 1. By doing so, a silicon hybrid thin film photoelectric conversion module in which a back electrode layer separation groove 5a having a width of 60 μm is formed, and strip-like silicon thin film photoelectric conversion devices adjacent to the left and right as shown in FIG. 2 are electrically connected in series Was made.

This silicon-based hybrid thin film photoelectric conversion module is configured by 100 stages of silicon-based thin film photoelectric conversion devices having a width of 8.9 mm and a length of 430 mm connected in series.
Pseudo-sunlight with an energy density of 100 mW / cm ² with a spectrum approximated to air mass 1.5 is irradiated under the conditions of the measurement atmosphere and the temperature of the silicon-based hybrid thin film photoelectric conversion module 25 ± 1 ° C. The current-voltage characteristics of the conversion module were measured. Table 1 shows the measurement results of open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF), and conversion efficiency (Eff).

In Table 1, the characteristic (1 cm2 square conversion) of the silicon-type hybrid thin film photoelectric conversion module in a 910 mm x 455 mm board | substrate is shown.

(Comparative Example 1)
In Comparative Example 1, compared with Example 1, only the holder of the plasma CVD apparatus for forming the crystalline photoelectric conversion unit 4 is changed to the conventional holder shown in FIG. A silicon-based hybrid thin film photoelectric conversion module was manufactured. Table 1 shows the output measurement results of the silicon-based hybrid thin film photoelectric conversion module fabricated in Comparative Example 1. Moreover, FIG. 12 shows Eff of Example 1 and Comparative Example 1 when E / S is changed.

  From comparison between Example 1 and Comparative Example 1 in Table 1 and FIG. 12, it can be seen that in Example 1, Voc and Jsc are improved and Eff is gradually improved as E / S becomes narrower. First, when E / S = 10 mm or more, Eff in both Example 1 and Comparative Example 1 gradually improved as E / S narrowed, and the absolute value of Eff in Example 1 and Comparative Example 1 is Only 0.2%. However, as E / S = 8 mm or less, Eff of Comparative Example 1 gradually decreases as E / S becomes narrower, and when E / S = 6 mm, Eff = 11.0%. On the other hand, Eff of Example 1 gradually increases as E / S becomes narrower, and it can be seen that Eff = 13.3% when E / S = 6 mm. The maximum value of Eff is 12.5% when Comparative Example 1 is E / S = 10 mm, whereas Example 1 is 13.3% when E / S = 6 mm. It can be seen that the value exceeds 0.8%.

From the above, according to the present invention, at least
(A) a high-frequency electrode;
(B) a substrate disposed opposite to the high-frequency electrode;
(C) A method of manufacturing a silicon-based thin film photoelectric conversion device including a step of using a plasma CVD apparatus that is disposed to face the high-frequency electrode and includes a holder that holds the substrate. ) And (ii) are amorphous photoelectric conversion units including an amorphous silicon photoelectric conversion layer or crystalline photoelectric including a crystalline silicon photoelectric conversion layer by a plasma CVD method performed in the arrangement state of (iii) By producing a silicon-based thin film photoelectric conversion device characterized by producing at least one conversion unit, Voc and Jsc of the silicon-based thin film photoelectric conversion device can be improved, and Eff can be improved.
(I) A film-forming surface that is a substrate surface facing the high-frequency electrode of the substrate (B).
(Ii) a surface that forms part of the holder (C) and faces the high-frequency electrode;
A surface closest to the substrate end in a direction parallel to the film forming surface and closest to the high-frequency electrode.
(Iii) The state arrange | positioned on the substantially the same plane.

Schematic cross-sectional view of a silicon-based hybrid thin film photoelectric conversion device Schematic cross section of a silicon-based hybrid thin film photoelectric conversion module Schematic sectional view of a conventional holder 1 Schematic sectional view of a conventional holder 2 Schematic cross section of the new holder Schematic plan view of the new holder as seen from the film forming surface Specific structure of the substrate holder in the new holder (cross-sectional view) Arrangement example 1 of new holder and high frequency electrode Arrangement example 2 of new holder and high frequency electrode Arrangement example 3 of new holder and high frequency electrode Arrangement example 4 of new holder and high frequency electrode Relationship between E / S and Eff of Example 1 and Comparative Example 1 Schematic structure of substrate fastening member

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Transparent electrically conductive film 3 Amorphous photoelectric conversion unit 3p Amorphous p-type silicon carbide layer 3i Non-doped amorphous i-type silicon photoelectric conversion layer 3n N-type silicon layer 4 Crystalline photoelectric conversion unit 4p p-type Crystalline silicon layer 4i Crystalline i-type silicon photoelectric conversion layer 4n n-type crystalline silicon layer 5 Back electrode layer 5t Transparent reflection layer 2a Transparent electrode layer separation groove 4a Connection groove 5a Back electrode layer separation groove 7 Substrate film surface 8 Holder Surface 9 High-frequency electrode surface 10 Holder 11 Substrate 12 Holding plate 13 Outer frame 14 Step portion 15 Fixing member 16 Auxiliary frame member 17 Auxiliary frame member step portion 20 New holder 21 Substrate fastening member 22 Spring 23 Line contact type substrate fastening member 24 Point contact Mold substrate fixing member 30 Electrode 31 High frequency electrode 32 Insulating member 33 Earth shield 34 Insulating member 35 Projection

Claims (3)

at least,
(A) a high-frequency electrode;
(B) a substrate disposed opposite to the high-frequency electrode;
(C) A method of manufacturing a silicon-based thin film photoelectric conversion device including a plasma CVD process using a plasma CVD device that is disposed to face the high-frequency electrode and includes a holder that holds the substrate. (I) and (ii) are performed by plasma CVD performed in the arrangement state of (iii),
Production of a silicon-based thin film photoelectric conversion device, comprising at least one amorphous photoelectric conversion unit including an amorphous silicon photoelectric conversion layer or at least one crystalline photoelectric conversion unit including a crystalline silicon photoelectric conversion layer Method.
(I) A film-forming surface that is a substrate surface facing the high-frequency electrode of the substrate (B).
(Ii) a surface that forms part of the holder (C) and faces the high-frequency electrode;
A surface closest to the substrate end in a direction parallel to the film forming surface and closest to the high-frequency electrode.
(Iii) The state arrange | positioned on the substantially the same plane.   2. The silicon-based thin film photoelectric conversion device according to claim 1, wherein the holder (C) has means for holding (B) from a side surface with respect to a film forming surface of the substrate (B). 3. Manufacturing method.   The shortest distance between a film-forming surface, which is a substrate surface facing the high-frequency electrode of the substrate (B), and a main surface of the high-frequency electrode (A) is greater than 0 mm and 8 mm or less. Item 3. A method for producing a silicon-based thin film photoelectric conversion device according to Item 1 or 2.