JP3624025B2 - Method for forming photovoltaic element - Google Patents

Description

【０１３５】
【表２】

【０１３６】
【表３】

【０１３７】
【表４】

【０１３８】
【表５】

【０１３９】
【表６】

【０１４０】
【表７】

【０１４１】
【表８】

【０１４２】
【表９】

【０１４３】
【表１０】

【０１４４】
【発明の効果】
以上説明したように、本発明によれば、光電変換効率が高く、かつ、モジュール間の光電変換効率のバラツキが小さい、光起電力素子の形成方法が得られる。
【図面の簡単な説明】
【図１】本発明に係る形成装置の一例を示す模式的断面図である。
【図２】本発明に係る形成装置の他の一例を示す模式的断面図である。
【図３】本発明に係る形成装置を構成するマイクロ波プラズマＣＶＤ法による成膜室の一例を示す模式的断面図である。
【図４】本発明に係る形成装置を構成する高周波プラズマＣＶＤ法による成膜室の一例を示す模式的断面図である。
【図５】本発明に係る形成装置を構成する高周波プラズマＣＶＤ法による成膜室の他の一例を示す模式的断面図である。
【図６】本発明に係る光起電力素子の層構成の一例を示す模式的断面図である。
【図７】本発明に係る光起電力素子の層構成の他の一例を示す模式的断面図である。
【符号の説明】
１０１、２０１ 帯状基体の巻き出し室、
１０２Ａ、１０２Ｂ、１０２Ｃ、２０２Ａ、２０２Ｂ、２０２Ｃ 高周波プラズマＣＶＤ法によるｎ型半導体層の成膜室、
１０３Ａ、１０３Ｂ、１０３Ｃ、２０３Ａ、２０３Ｂ、２０３Ｃ 高周波プラズマＣＶＤ法によるｉ型半導体層の成膜室、
１０４Ａ、１０４Ｂ、１０４Ｃ、２０４Ａ、２０４Ｂ 高周波プラズマＣＶＤ法によるｐ型半導体層の成膜室、
２０４Ｃ プラズマドーピングによるｐ型半導体層の成膜室、
１０５、２０５ 帯状基体の巻き取り室、
１０６、２０６、３０３、３０４、４０３、５０３、５０４ ガスゲート、
１０７、２０７、３０１、４０１、５０１ 帯状基体、
１０８、２０８ 帯状基体の巻き出しボビン、
１０９、２０９ 帯状基体の巻き取りボビン、
２１０Ａ、２１０Ｂ マイクロ波プラズマＣＶＤ法によるｉ型半導体層の成膜室、
２１１Ａ、２１１Ｂ 高周波プラズマＣＶＤ法によるｉ型半導体層の成膜室、
２１２、２１３、２１４ 高周波プラズマＣＶＤ法によるｎ型半導体層の成膜室、
３０２、４０２、５０２Ａ、５０２Ｂ、５０２Ｃ 真空容器、
３０５ 放電室ユニット、
３０６、３０７、３０８ 成膜室、
３０９、４０７、５０７Ａ、５０７Ｂ、５０７Ｃ 原料ガス導入管、
３１２ 圧力測定管、
３１５、３１６、３１７ バイアス電極、
３１８、３１９、３２０ マイクロ波導入窓、
３２１、３２２、３２３、３２４ 穴開き仕切板、
３２５、３２６、４０８、５０８Ａ、５０８Ｂ、５０８Ｃ 排気管、
３２７ 荒引き用排気管、
３２８ 粉受け板、
３２９、４１１、５１１ プラズマ漏れガード、
３３０ 成膜室温度制御装置、
３３１、４１２、５１２Ａ、５１２Ｂ、５ｌ２Ｃ 蓋、
３３２、４１３、４１４、５１３Ａ、５１４Ａ、５１３Ｂ、５１４Ｂ、５１３Ｃ、５１４Ｃ ランプヒーター、
３３３、３３４、３３５ 基体温度制御装置、
３３６、３３７、３３８、３３９、４１５、４１６、５１５Ａ、５１６Ａ、５１５Ｂ、５１６Ｂ、５１５Ｃ、５１６Ｃ 熱電対、
３４０、４１７、５１７Ａ、５１７Ｂ、５１７Ｃ リフレクター、
３４１、３４５、４１８、５１８ 支持ローラー、
４４２、５４２ 分離通路、
３４３、３４４、４４３、４４４、５４３、５４４ ゲートガス導入管、
４０５、５０５Ａ、５０５Ｂ、５０５Ｃ 放電室、
４０６、５０６Ａ、５０６Ｂ、５０６Ｃ 放電電極、
４０９、５０９Ａ、５０９Ｂ、５０９Ｃ ブロックヒーター、
４１０、５１０Ａ、５１０Ｂ、５１０Ｃ 放電室外部排気口、
６０１、７０１ 基体、
６０２Ａ、６０２Ｂ、６０２Ｃ、７０２Ａ、７０２Ｂ、７０２Ｃ 高周波プラズマＣＶＤ法によるｎ型半導体層、
６０３Ａ、６０３Ｂ、６０３Ｃ、７０３Ａ、７０３Ｂ、７０３Ｃ、７０８Ａ、７０８Ｂ 高周波プラズマＣＶＤ法によるｉ型半導体層、
６０４Ａ、６０４Ｂ、６０４Ｃ、７０４Ａ、７０４Ｂ 高周波プラズマＣＶＤ法によるｐ型半導体層、
６０４Ｃ、７０４Ｃ プラズマドーピングによるｐ型半導体層、
７０７Ａ、７０７Ｂ マイクロ波プラズマＣＶＤ法によるｉ型半導体層、
６０５、７０５ 透明導電膜、
６０６、７０６ 集電電極。[0001]
[Industrial application fields]
The present invention Method for forming photovoltaic element Concerning. More specifically, in a photovoltaic device in which at least two structures consisting of nip junctions are stacked, the problem of hindering the movement of optical carriers generated by photoelectric conversion caused by the reverse junction portion is solved. did, Method for forming photovoltaic element Concerning.
[0002]
[Description of Related Art]
In recent years, power demand has increased rapidly worldwide, and production of various types of power has become active. However, along with this, problems of environmental pollution and global warming caused by thermal power generation and nuclear power generation have become obvious. Under these circumstances, solar power generation using sunlight will not cause problems of environmental pollution and global warming, and solar resources are not evenly distributed on the earth. Collecting.
[0003]
By the way, in order to put solar cell power generation into practical use, development of a technology relating to higher photoelectric conversion efficiency, more excellent characteristics and stability, and a structure suitable for mass production is expected. In addition, a large-area solar cell is required in order to increase the power generation scale.
[0004]
From such a background, it is formed by depositing a semiconductor thin film such as amorphous silicon on a relatively inexpensive substrate such as glass or metal sheet by decomposing a readily available source gas such as silane by glow discharge. Amorphous silicon solar cells have been proposed. In particular, this amorphous silicon solar cell is attracting attention because it is superior in mass productivity and low in cost compared to a solar cell made of single crystal silicon or the like, and various proposals have been made regarding its manufacturing method. Has been made.
[0005]
US Pat. No. 4,400,409 discloses a roll-to-roll method as an example of a method for forming a deposited film by plasma CVD suitable for producing an amorphous silicon solar cell. . In this deposited film forming method, a plurality of glow discharge regions are provided, a long belt-like substrate is disposed along a path through which the substrate sequentially passes through each glow discharge region, and a required conductive type semiconductor layer is formed. The belt-like substrate is continuously conveyed in the longitudinal direction while being deposited in each glow discharge region. Thereby, a solar cell having a desired semiconductor junction can be formed continuously. In this deposited film formation method, in order to prevent the dopant gas used in each glow discharge region from diffusing and mixing into other glow discharge regions, each glow discharge region is separated by a slit-like separation passage called a gas gate. They are separated from each other, and in this separation passage, for example, Ar, H ₂ Such as scavenging gas flow is formed. With such a configuration, the deposited film forming method by the roll-to-roll method is suitable for manufacturing semiconductor elements such as solar cells.
[0006]
By the way, amorphous silicon solar cells have a characteristic deterioration phenomenon (Staebler-Wronski effect) due to light irradiation, which is not found in crystalline solar cells. In order to achieve high efficiency and low cost based on large-area production technology, and to put it to practical use as a power application, it is important to reduce this characteristic deterioration phenomenon.
[0007]
Regarding the above-mentioned characteristic deterioration phenomenon due to light irradiation, many studies have been conducted on the mechanism elucidation and the countermeasures against it from the aspects of semiconductor materials such as impurity reduction and characteristic recovery processing such as heat annealing. Has been done. In particular, the adoption of a tandem element structure in which unit power generation elements having a semiconductor junction such as pin are stacked in multiple layers of double, triple, or more can reduce the film thickness of each i-type semiconductor layer. , Light degradation can be suppressed. Further, the tandem element structure has been attracting attention in recent years because high efficiency can be achieved by stacking solar cells having different band gaps. In particular, among the tandem element structures, the three-layer tandem type can use a wider wavelength region of the incident light spectrum than the two-layer tandem type, so that high photoelectric conversion efficiency can be obtained and a higher output voltage can be obtained. It is excellent in that it can be obtained.
[0008]
However, in the tandem type element in which the unit power generation elements are directly joined, since the junction between the unit power generation elements is opposite to the semiconductor junction in each unit power generation element, the movement of the photocarrier generated by photoelectric conversion is inhibited, This is a problem for practical use. For example, in U.S. Pat. No. 4,272,641, when the impurity addition amount of the impurity layer of the different unit power generation elements constituting the reverse junction in the tandem type photovoltaic element is sufficiently high, the optical carriers are tunneled by the tunnel phenomenon. Although the tunnel junction layer is theoretically formed in advance, in reality, an impurity layer with a high impurity addition amount leading to the formation of the tunnel junction layer cannot be obtained, and a metal layer such as Pt is placed between the unit power generation elements. Proposes an intervening structure.
[0009]
[Problems to be solved by the invention]
The present invention has a problem in which the movement of photocarriers generated by photoelectric conversion due to the reverse junction portion is hindered in a photovoltaic device in which at least two structures each having a nip or pin junction are provided in an overlapping manner. Can be reduced Method for forming photovoltaic element The purpose is to provide.
[0010]
[Means for Solving the Problems]
Photovoltaic element of the present invention Forming method Is a structure comprising a nip junction laminated on the substrate in the order of n, i and p, where p is the p-type semiconductor layer, i is the i-type semiconductor layer and n is the n-type semiconductor layer. In the photovoltaic element provided by superposing at least two or more, when the lower layer of the reverse junction where the structures are in contact with each other is p ′, the upper layer is n ′, Between the step of forming the p ′ and the step of forming the n ′, the step of heat-treating the substrate formed up to the p ′ at a temperature higher than the substrate temperature when forming the n ′. Provided It is characterized by that.
[0013]
[Action]
In the invention according to claim 1, when the p-type semiconductor layer is p, the i-type semiconductor layer is i, and the n-type semiconductor layer is n, the n, the i, and the p layers are stacked on the base. In a photovoltaic device in which at least two structures composed of nip junctions are overlapped, when p ′ is the lower layer of the reverse junction where the structures are in contact with each other and n ′ is the upper layer, formation is performed up to p ′ Since the n ′ is formed after the heated substrate is heated at a temperature higher than the substrate temperature at the time of forming the n ′, an abnormal current-voltage characteristic is not observed, and nipnipnip having high photoelectric conversion efficiency A three-layer tandem photovoltaic device having a structure was obtained.
[0014]
This is a phenomenon that cannot be conceived from the conventional idea of increasing the amount of impurities added to the impurity layer or interposing a metal layer between unit power generation elements.
[0015]
There are three possible reasons why such an action is obtained.
First, by heating the substrate on which the nip structure or the nipnip structure is deposited, hydrogen intervening in the p-type semiconductor layer that is the outermost surface layer, particularly the amorphous silicon film near the surface, is desorbed, This is because there are a large number of dangling bonds, the localized levels existing between the band gaps are increased, and the optical carriers are easily tunneled at the interface.
[0016]
Second, by heating the substrate on which the nip structure or the nipnip structure is deposited, hydrogen intervening in the p-type semiconductor layer as the outermost surface layer, particularly the amorphous silicon film near the surface is desorbed. The added impurity becomes active, the impurity level is increased, and the photocarrier is easily tunneled at the p / n interface.
[0017]
Thirdly, by heating the substrate on which the nip structure or the nipnip structure is deposited, the added impurities in the p-type semiconductor layer, which is the outermost surface layer, become active, and the p-type semiconductor layer is diffused. This is because the impurity level in the type semiconductor layer is increased and the optical carriers are easily tunneled at the p / n interface.
[0018]
The present invention Then, between the step of forming the p ′ and the step of forming the n ′, the substrate formed up to the p ′ is heat-treated at a temperature higher than the substrate temperature when forming the n ′. Because we set up a process, Said A method for forming a photovoltaic element capable of producing the photovoltaic element is obtained.
[0020]
Embodiment Example
(Substrate)
As the substrate according to the present invention, a belt-like substrate having a longitudinal direction in the direction in which the substrate is conveyed is preferably used.
[0021]
As the material of the band-shaped substrate, it is preferable that the material has a desired strength and is less deformed and distorted at a temperature required when the semiconductor film is produced, specifically stainless steel, Aluminum and its alloys, iron and its alloys, copper and its metal thin plates and their composites, and metal thin films and / or SiO of different materials on their surfaces ₂ , Si ₃ N ₄ , Al ₂ O ₃ Insulating thin film such as AlN, etc., which has been surface-coded by sputtering, vapor deposition, plating, etc. In addition, a simple metal or alloy and transparent conductive oxide on the surface of a heat-resistant resin sheet such as polyimide, polyamide, polyethylene terephthalate, epoxy, or a composite of these with glass fiber, carbon fiber, boron fiber, metal fiber, etc. (TCO) etc. which performed the electroconductive process by methods, such as plating, vapor deposition, sputtering, application | coating, are mentioned.
[0022]
In addition, the thickness of the band-shaped substrate is as thin as possible in consideration of cost, storage space, etc., as long as it is within a range in which the curved shape produced at the time of conveyance by the conveying means is maintained. Is desirable. Specifically, it is preferably 0.01 mm to 5 mm, more preferably 0.02 mm to 2 mm, and most preferably 0.05 mm to 1 mm. However, when a thin plate such as a metal is used, the thickness is relatively Even if it is thinned, a desired strength can be easily obtained. The width dimension of the band-shaped substrate is preferably a size that maintains the uniformity of plasma formed in each film forming chamber and is suitable for modularization of the photovoltaic element to be formed. Preferably it is 5 cm to 100 cm, more preferably 10 cm to 80 cm. The length of the band-shaped substrate is not particularly limited, and may be a length that can be wound in a roll shape, which is a longer one that is further elongated by welding or the like. Also good.
[0023]
When the belt-like substrate is electrically conductive such as metal, it may be used as an electrode for direct current extraction, and when it is electrically insulating such as synthetic resin, Al is formed on the surface on which the semiconductor film is formed. , Ag, Pt, Au, Ni, Ti, Mo, W, Fe, V, Cr, Cu, stainless steel, brass, nichrome, SnO ₂ , In ₂ O ₃ ZnO, SnO ₂ -In ₂ O ₃ It is desirable that a so-called metal simple substance or alloy such as (ITO) and TCO are subjected to surface treatment in advance by a method such as plating, vapor deposition, sputtering, or the like to prepare an electrode for extracting current.
[0024]
When the band-shaped substrate is a non-translucent material such as a metal, a reflective conductive film for improving the reflectance of the long-wavelength light on the substrate surface is formed on the band-shaped substrate as described above. Is preferred. Examples of materials that can be suitably used as the material for the reflective conductive film include Ag, Al, and Cr. In addition, for the purpose of preventing interdiffusion of constituent elements between the base material and the semiconductor film or forming a buffer layer for preventing a short circuit, the semiconductor film on the base is made of a metal layer or the like as a reflective conductive film. It is preferably provided on the side to be produced. An example of a suitable material for the buffer layer is ZnO.
[0025]
In the case of a solar cell having a layer structure in which the band-shaped substrate is relatively transparent and light is incident from the band-shaped substrate side, a conductive thin film such as the transparent conductive oxide or metal thin film is previously formed. It is desirable to make a deposit.
[0026]
Further, the surface property of the band-shaped substrate may be a so-called smooth surface or a minute uneven surface. In the case of a minute uneven surface, it has a spherical shape, a conical shape, a pyramid shape, etc., and its maximum height (R _max ) Is preferably 50 nm to 500 nm, the light reflection on the surface becomes irregular reflection, resulting in an increase in the optical path length of the reflected light on the surface.
[0027]
It is desirable that the belt-like substrate as described above is loaded into the apparatus of the present invention in a form in which the cylindrical bobbin is wound in a coil shape with a diameter within a range not plastically deformed.
[0028]
(Temperature control mechanism for belt-shaped substrate)
An example of the temperature control mechanism for the band-shaped substrate according to the present invention is shown in FIG. In FIG. 4, lamp heaters 413 and 414 are arranged on the upper surface (back surface) side of the band-like substrate 401 in the vacuum vessel 402 and fixed to the openable / closable lid 412 of the vacuum vessel 402 in the film forming chamber by the high-frequency plasma CVD method. The belt-shaped substrate 401 is temperature-controlled from the back surface to a predetermined temperature while monitoring the temperature by the thermocouples 415 and 416 that are provided and are in surface contact with the back surface of the belt-shaped substrate. The lamp heater 413 is called a pre-heater, and the lamp heater 414 is called a heater.
[0029]
The temperature of the belt-like substrate 401 is lowered when passing through the gas gate 403, but the lamp heater 413 provided in front of the discharge chamber 405 reaches a predetermined temperature suitable for film formation until the belt-like substrate reaches the discharge chamber 405. The temperature is maintained by the lamp heater 414 provided on the discharge chamber 405 so that the temperature is kept constant during the formation of the deposited film.
[0030]
Each of the lamp heaters 413 and 414 has a structure in which a plurality of rod-shaped infrared lamps having a length capable of uniformly heating the width of the belt-like substrate are arranged in a direction perpendicular to the moving direction of the belt-like substrate. The interval is adjusted so that it becomes denser as it goes behind the discharge chamber 405. The lamp heaters 413 and 414 are provided with a double reflector 417 to collect the radiated light from the lamps on the side of the belt-like substrate to increase the heating efficiency and prevent the vacuum vessel lid 412 from being heated. doing. In addition, a wiring cover (not shown) is provided in the electric wiring for supplying power to the lamp heaters 413 and 414 so that even if plasma leaks from the discharge chamber 405, no spark or leakage occurs from the electric wiring. Yes.
[0031]
(Support mechanism for belt-like substrate)
An example of the support mechanism for the belt-like substrate according to the present invention is shown in FIG. In FIG. 4, a support roller 418 for rotating and supporting the back surface of the belt-like substrate is provided in the vicinity of the inlet and outlet of the vacuum vessel 405 in the vacuum vessel 402 in the film formation chamber by the high-frequency plasma CVD method. The substrate 401 is stretched linearly and supported from the back surface so that the distance from the discharge electrode 406 is kept constant.
[0032]
The support roller 418 has a curie point, a permanent magnet (not shown) that generates a magnetic force that does not affect the plasma, and a belt-like substrate made of a magnetic material such as ferritic stainless steel. In this case, the support roller 418 and the belt-like substrate 401 are brought into close contact with each other. Further, the surface of the support roller 418 is formed of a conductive material such as stainless steel and is electrically grounded, and the conductive belt-like substrate 401 is electrically grounded.
[0033]
(Gas gate)
In the gas gate according to the present invention, adjacent film forming chambers are connected by a slit-shaped separation passage, and Ar, He, H, for example, are connected to the separation passage. ₂ A connecting means between film forming chambers for separating a source gas by moving a belt-like substrate between adjacent film forming chambers by introducing a gas such as a gas flow toward the film forming chamber.
[0034]
FIG. 4 is a schematic cross-sectional view showing an example of various film forming chambers and gas gates connecting them in the present invention. The gas gates shown in FIG. 4 have basically the same structure.
[0035]
The gas gate 403 in FIG. 4 includes a slit-shaped separation passage 442 that allows the strip-shaped substrate 401 to pass therethrough and separates the source gas. Gate gas introduction pipes 443 and 444 having a plurality of gas introduction terms in the width direction of the belt-like substrate and connected to a gate gas supply system (not shown) are connected to the upper and lower sides of the belt-like substrate in the substantially central portion of the separation passage 442. A source gas separation gate gas is introduced from above and below the belt-like substrate 401. Further, in the separation passage 442, the back surface of the belt-like substrate 401 is rotationally supported by a plurality of support rollers 445 so that the surface thereof does not contact the lower wall surface of the separation passage 442 and maintains a constant slight gap. . When a belt-like substrate made of a magnetic material such as ferritic stainless steel is used inside the support roller 445, a permanent magnet (not shown) that has a high Curie point and generates a magnetic force that does not affect the plasma is used. In addition, the support roller 445 and the belt-like substrate 401 are brought into close contact with each other.
[0036]
In addition, the slit-shaped separation passage 442 prevents the band-shaped substrate from waving or vibrating when moving so that the semiconductor film forming surface of the band-shaped substrate contacts the lower surface of the inner wall of the separation passage and is not damaged. Should be wide in the thickness direction of the band-shaped substrate and short in the moving direction of the band-shaped substrate, and narrow in the thickness direction of the band-shaped substrate, Longer is better. Therefore, the inner dimension in the width direction of the strip-shaped substrate of the slit-shaped separation passage 442 is almost constant everywhere at a slightly larger width than the width of the band-shaped substrate, but the inner dimension in the thickness direction of the strip-shaped substrate is the same as that of the film forming chamber to be connected. The narrower the pressure difference is, the smaller the allowable amount of impurity gas is.
[0037]
For example, an i-type layer film formation chamber by microwave CVD has a low internal pressure and a small allowable amount of impurity gas, so that the internal pressure is relatively high, and an impurity addition layer film formation chamber by high frequency plasma CVD that introduces impurity gas The gas gates connecting the two are narrowed to the extent that the band-shaped substrate can finally pass through the thickness direction of the strip-shaped substrate of the separation passage, and is set in a range of about 0.3 to 3 mm. On the other hand, in the gas gate that connects between the unwinding chamber and the winding chamber of the belt-shaped substrate with almost no pressure difference and the film formation chamber of the high-frequency plasma CVD method, the inner dimension in the thickness direction of the belt-shaped substrate of the separation path is the band-shaped substrate. Is relatively wide so that it can be easily moved, and is set in a range of about 1 mm to 5 mm.
[0038]
(Forming equipment)
In the following, an example of a forming apparatus according to the present invention constituted by each of the film forming chambers described above with reference to the drawings is shown, but the present invention is not limited to these forming apparatuses.
[0039]
(Device Example 1)
FIG. 1 is a schematic explanatory view showing a basic example of an apparatus for continuously forming a semiconductor laminated film according to the present invention. Referring to FIG. 1, a continuous semiconductor film forming apparatus of the present invention includes a strip-shaped substrate unwinding chamber 101, an n-type layer film forming chamber 102A by a high-frequency plasma CVD method, an i-type layer film forming chamber 103A by a high-frequency plasma CVD method, P-type layer deposition chamber 104A by plasma CVD, n-type layer deposition chamber 102B by high-frequency plasma CVD, i-type layer deposition chamber 103B by high-frequency plasma CVD, p-type layer deposition chamber 104B by high-frequency plasma CVD , An n-type layer film forming chamber 102C by a high-frequency plasma CVD method, an i-type layer film forming chamber 103C by a high-frequency plasma CVD method, a p-type layer film forming chamber 104C by plasma doping, and a belt-like substrate winding chamber 104. .
[0040]
The series of film forming chambers are arranged in a convex shape in the gravitational direction such as a suspended curve shape or an arc shape along the shape of the belt-like substrate that hangs down by its own weight, and the belt-like substrate is stretched without slack by a slight tension. While maintaining a constant shape during film formation, the stress applied to the band-shaped substrate and the semiconductor film formed thereon during movement of the band-shaped substrate is reduced to suppress the deformation of the substrate and the occurrence of film defects due to the stress. ing.
[0041]
In the apparatus of FIG. 1, the strip-shaped substrate 107 is unwound from the bobbin 108 of the strip-shaped substrate unwinding chamber 101 and is connected by the gas gate 106 before being wound on the bobbin 109 of the strip-shaped substrate winding chamber 105. The film is moved while passing through the film forming chamber, and a non-single crystal semiconductor laminated film having a nipnipnip structure is continuously formed on the surface thereof.
[0042]
The belt-like substrate 107 supplied from the belt-like substrate unwinding chamber 101 is processed in the following order (1) to (11) through a gas gate.
[0043]
(1) Enters the n-type layer deposition chamber 102A by the high-frequency plasma CVD method, and an n-type silicon-based non-single-crystal semiconductor layer is formed on the surface by the high-frequency plasma CVD method.
(2) Enter the i-type layer deposition chamber 103A by high-frequency plasma CVD, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by high-frequency plasma CVD.
[0044]
(3) Enter the p-type layer deposition chamber 104A by the high-frequency plasma CVD method, and further form and stack a p-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
(4) Enter the n-type layer deposition chamber 102B by the high-frequency plasma CVD method, and the band-shaped substrate is heated together with the semiconductor layer formed on the band-shaped substrate.
[0045]
(5) Enters the n-type layer deposition chamber 102B by the high-frequency plasma CVD method, and further forms and stacks an n-type silicon non-single crystal semiconductor layer by the high-frequency plasma CVD method.
(6) Enter the i-type layer deposition chamber 103B by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0046]
(7) Enter the i-type layer deposition chamber 104B by the high-frequency plasma CVD method, and further form and stack a p-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
(8) Enter the n-type layer deposition chamber 102C by the high-frequency plasma CVD method, and the band-shaped substrate is heated together with the semiconductor layer formed on the band-shaped substrate.
[0047]
(9) The n-type layer deposition chamber 102C is formed by high-frequency plasma CVD, and an n-type silicon-based non-single-crystal semiconductor layer is further formed and stacked by high-frequency plasma CVD.
(10) Enter the i-type layer deposition chamber 103C by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0048]
(11) Enters the p-type layer deposition chamber 104C by plasma doping, further forms and stacks a p-type silicon-based non-single-crystal semiconductor layer by plasma doping, and finally collects it in the winding chamber 105 of the belt-like substrate Is done.
[0049]
(Device example 2)
FIG. 2 is a schematic explanatory view showing another example of the semiconductor multilayer film continuous forming apparatus of the present invention. In FIG. 2, the semiconductor film continuous forming apparatus of the present invention includes a strip-shaped substrate unwinding chamber 201, an n-type layer film forming chamber 202A by a high-frequency plasma CVD method, an i-type layer film forming chamber 203A by a high-frequency plasma CVD method, An i-type layer film forming chamber 210A by a wave plasma CVD method, an i-type layer film forming chamber 211A by a high-frequency plasma CVD method, a p-type layer film forming chamber 204A by a high-frequency plasma CVD method, a heating chamber 212 for a strip substrate, a high-frequency plasma CVD method N-type layer film formation chambers 213 and 214, high-frequency plasma CVD method i-type layer film formation chamber 203B, microwave plasma CVD method i-type layer film formation chamber 210B, high-frequency plasma CVD method i-type layer film formation chamber 211B , P-type layer deposition chamber 204B by high-frequency plasma CVD method, n-type layer deposition chamber 202C by high-frequency plasma CVD method, i-type layer deposition chamber 203C by wave plasma CVD method, p-type layer deposition chamber 204C by plasma doping, and a winding chamber 205 of the annular base.
[0050]
The series of film forming chambers are arranged in a convex shape in the gravitational direction such as a suspended curve shape or an arc shape along the shape of the belt-like substrate that hangs down by its own weight, and the belt-like substrate is stretched without slack by a slight tension. While maintaining a constant shape during film formation, the stress applied to the band-shaped substrate and the semiconductor film formed thereon during movement of the band-shaped substrate is reduced to suppress the deformation of the substrate and the occurrence of film defects due to the stress. ing.
[0051]
In the apparatus of FIG. 2, the strip-shaped substrate 207 is unwound from the bobbin 208 of the strip-shaped substrate unwinding chamber 201 and is connected by the gas gate 206 until being wound on the bobbin 209 of the strip-shaped substrate winding chamber 205. The film is moved while passing through the film forming chamber, and a non-single crystal semiconductor laminated film having a nipnipnip structure is continuously formed on the surface thereof.
[0052]
The band-shaped substrate 207 supplied from the unwinding chamber 201 of the band-shaped substrate is processed in the order of (1) to (15) shown below through a gas gate.
[0053]
(1) Entering the n-type layer deposition chamber 202A by the high-frequency plasma CVD method, and an n-type silicon-based non-single-crystal semiconductor layer is formed on the surface by the high-frequency plasma CVD method.
(2) Enters the i-type layer deposition chamber 203A by the high-frequency plasma CVD method, and further forms and stacks an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0054]
(3) Enter the i-type layer deposition chamber 210A by microwave plasma CVD, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by microwave plasma CVD.
(4) Enter the i-type layer deposition chamber 211A by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0055]
(5) Enter the p-type layer deposition chamber 204A by the high-frequency plasma CVD method, and further form and stack a p-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
(6) Enter the heating chamber 212 of the band-shaped substrate, and the band-shaped substrate is heated together with the semiconductor layer formed on the band-shaped substrate.
[0056]
(7) Enter the n-type layer deposition chambers 213 and 214 by the high-frequency plasma CVD method, and further form and stack an n-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
(8) Enter the i-type layer deposition chamber 203B by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0057]
(9) Enter the i-type layer deposition chamber 210B by the microwave plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the microwave plasma CVD method.
(10) Enter the i-type layer deposition chamber 211B by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0058]
(11) Enter the p-type layer deposition chamber 204B by the high-frequency plasma CVD method, and further form and stack a p-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
(12) Enter the n-type layer deposition chamber 202C by the high-frequency plasma CVD method, and the strip substrate is heated together with the semiconductor layer formed on the strip substrate.
[0059]
(13) The n-type layer deposition chamber 202C is formed by high-frequency plasma CVD, and an n-type silicon-based non-single-crystal semiconductor layer is further formed and stacked by high-frequency plasma CVD.
(14) Enter the i-type layer deposition chamber 203C by the high-frequency plasma CVD method, and further form and stack an i-type silicon-based non-single-crystal semiconductor layer by the high-frequency plasma CVD method.
[0060]
(15) Enters the p-type layer deposition chamber 204C by plasma doping, further forms and stacks a p-type silicon-based non-single crystal semiconductor layer by plasma doping, and finally collects it in the winding chamber 205 of the belt-like substrate Is done.
[0061]
(Device Example 3)
A device obtained by removing the i-type semiconductor layer forming chamber 203A and / or 203B by the high-frequency plasma CVD method of FIG. In this case, except that the i-type semiconductor layer is not formed on the at least one n-type semiconductor layer by the high-frequency plasma CVD method, the others are the same as the apparatus example 2.
[0062]
(Example 4)
A device obtained by removing the i-type semiconductor layer forming chambers 203A and / or 203B, 211A and / or 211B, and the gas gate connecting them from the high-frequency plasma CVD method of FIG. 2 can be given as an example of the apparatus of the present invention. In this case, only the i-type semiconductor layer formed by the high-frequency plasma CVD method is not formed on the at least one i-type semiconductor layer formed by the microwave CVD method.
[0063]
(Device Example 5)
A device obtained by removing the i-type semiconductor layer forming chamber 211A and / or 211B by the high-frequency plasma CVD method of FIG. 2 and the gas gate connecting it can be given as an example of the apparatus of the present invention. In this case, the i-type semiconductor layer formed by the high-frequency plasma CVD method is not formed on the at least one n-type semiconductor layer, and the i-type semiconductor layer formed by the high-frequency plasma CVD method is formed on the i-type semiconductor layer formed by one microwave CVD method. Otherwise, the rest is the same as device example 2.
[0064]
(Formation method)
Hereinafter, the method for forming the photovoltaic element of the present invention using the above-described forming apparatus will be described with reference to the drawings, but the present invention is not limited to these forming methods.
[0065]
(Semiconductor layer formation process)
After preheating and baking of each film forming chamber, the shaft of the take-up bobbin 109 of the belt-shaped substrate winding chamber 105 is rotated to remove the belt-shaped substrate 107 from the unwinding chamber 101 to the film forming chambers 102A, 103A, 104A, 102B, and 103B. , 104B, 102C, 103C, 104C and continuously move to the winding chamber 105 at a constant speed. The moving speed of the band-shaped substrate is preferably 1 to 100 mm / second, more preferably 5 to 50 mm / second.
[0066]
While moving the band-shaped substrate, the temperature of the band-shaped substrate in the deposition film formation space of each film formation chamber is determined by the lamp heater, substrate temperature temperature control device, film formation chamber temperature control device, and block heater in each film formation chamber 102A-104C. The temperature of the wall surface of each film forming chamber is controlled to a predetermined temperature.
[0067]
When the temperature of the belt-shaped substrate is stabilized, H from the film formation chamber ₂ , He, Ar, Ne, Kr, Xe, etc. are stopped, and each of the film formation chambers 102A to 104C is evacuated by a vacuum pump connected to each of the film formation chambers. ₂ , He, Ar, Ne, Kr, Xe, etc. are introduced into each gas gate 106 from a gas cylinder through a mass flow controller.
[0068]
Next, a predetermined flow rate is introduced from a gas cylinder into the film forming chambers 102A to 104C through a mass flow controller.
[0069]
When the flow rate of the source gas in each film forming chamber is stabilized, the exhaust capacity of each film forming chamber is adjusted by an exhaust amount adjusting valve or the like provided in the exhaust pipe, and each film forming chamber is set to a predetermined pressure.
[0070]
The preferable internal pressure of each chamber when the source gas is introduced is 0.1 to 10 Pa in the film forming chamber by the microwave plasma CVD method, and 10 to 1000 Pa in the other chambers.
[0071]
In order to prevent the impurity gas from being mixed, the internal pressure of the n-type layer deposition chamber 102A is higher than the internal pressure of the strip-shaped substrate unwinding chamber 101, and the internal pressures of the i-type layer deposition chambers 103A, 103B, 103C are n-type layers. From the internal pressure of the film forming chambers 102A, 102B, and 102C, and from the internal pressure of the p-type film forming chambers 104A, 104B, and 104C, the internal pressure of the p-type film forming chamber 104C is It is desirable to set each slightly higher.
[0072]
When the pressure in each film formation chamber is stabilized, discharge power such as microwave power, high frequency power, low frequency power, and direct current power is supplied into each film formation chamber 102A to 104C. By supplying the discharge power, the source gas in each film forming chamber is ionized to form plasma.
[0073]
As described above, a plasma layer is simultaneously formed in each of the film forming chambers 102A to 104C while moving the band-shaped substrate at a constant speed, so that a semiconductor layer is formed in each film forming chamber on the continuously moving band-shaped substrate. Thus, a semiconductor laminated film having a nipnipniP structure is continuously formed.
At this time, the formation conditions of the respective semiconductor layers in the respective film formation chambers 102A to 104C are as follows.
[0074]
(Formation of n (or p) type semiconductor layer by high-frequency plasma CVD method)
In the deposition chambers 102A, 102B, 102C and 104A, 104B, an n (or p) type silicon-based non-single-crystal semiconductor layer is formed by a high-frequency plasma CVD method.
[0075]
The source gas introduced into the film forming chamber contains a gasifiable compound containing at least Si atoms. SiH containing gas atomizable compounds 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, Si ₂ D ₃ H ₃ Etc. The source gas may contain a gasatable compound containing Ge atoms for the purpose of narrowing the optical band gap.
[0076]
Specifically, GeH containing Ge atoms can be gasified. ₄ , GeD ₄ , GeF ₄ , GeFH ₃ , GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ , GeH ₂ D ₂ , GeH ₃ D etc. are mentioned. Furthermore, the source gas may contain a gasifiable compound containing atoms such as C, O, and N for the purpose of widening the optical band gap.
[0077]
Specifically, as a gasifiable compound containing a C atom, CH ₄ , CD ₄ , C _n H _{2n + 2} (N is an integer), C _n H _2n (N is an integer), C ₂ H ₂ , C ₆ H ₆ , CO ₂ , CO and the like.
[0078]
As gasifiable compounds containing O atoms, O ₂ , CO, CO ₂ , NO, NO ₂ , N ₂ O, CH ₃ CH ₂ OH, CH ₃ OH etc. are mentioned.
As a gasifiable compound containing N atom, N ₂ , NH ₃ , ND ₃ , NO, NO ₂ , N ₂ O etc. are mentioned.
[0079]
In addition, in the source gas, a gas containing Group V (or Group III) atoms in the periodic table in order to control the valence electrons of the non-single-crystal semiconductor layer formed to n (or p) type. Including compounds that can be converted to
[0080]
Examples of materials that can be used effectively as starting materials for introducing Group V atoms include PH for specifically introducing P atoms. ₃ , P ₂ H ₄ Phosphorus hydrides such as PH ₄ I, PF ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , PI ₃ And the like. In addition to AsH ₃ , AsF ₃ , AsCl ₃ , AsBr ₃ , AsF ₅ , SbF ₃ , SbF ₅ , SbCl ₃ , SbCl ₅ , BiH ₃ , BiCl ₃ , BiBr ₃ Etc. can also be mentioned. Especially PH ₃ , PF ₃ , AsH ₃ Is suitable.
[0081]
Effectively used as starting materials for introducing Group III atoms are specifically B for introducing B atoms. ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆ H ₁₂ , B ₆ H ₁₄ Boron hydride such as BF ₃ , BCl ₃ And the like. Besides this, AlCl ₃ , GaCl ₃ , InCl ₃ Etc. can also be mentioned. Especially B ₂ H ₆ , BF ₃ Is suitable. The source gas is H ₂ , D ₂ , He, Ne, Ar, Xe, Kr or the like may be included.
[0082]
The discharge power input to the film forming chamber is for forming high-frequency plasma, and includes at least high-frequency power. The high-frequency power to be input is appropriately determined according to the flow rate of the source gas introduced into the film forming chamber, but is 0.001 to 1 W / cm with respect to the area of the high-frequency generating electrode. ² It is desirable that the range is a stable continuous wave with little fluctuation such as ripple. The frequency of the high-frequency power is preferably in the range of 1 to 100 MHz, and an industrial frequency of 13.56 MHz is preferably used, and preferably has a small frequency fluctuation.
[0083]
DC power may be input together with high-frequency power, and a voltage of 10 to 200 V is applied to an electrode provided separately from the high-frequency discharge electrode and the discharge electrode in a direction in which the electrode side becomes positive within a range in which abnormal discharge such as spark does not occur. It is preferable to input.
[0084]
Such high-frequency power is input to the film forming chamber, preferably DC power is simultaneously input, the source gas is ionized and decomposed in the film forming chamber, and an n (or p) type silicon-based non-single material is formed on the band-shaped substrate. A crystalline semiconductor layer is formed.
[0085]
Note that the semiconductor layer formed under such film formation conditions is a non-single-crystal material ranging from amorphous silicon (including so-called microcrystals) to polycrystalline.
[0086]
(Formation of i-type semiconductor layer by microwave plasma CVD method)
In the apparatus of the present invention, the microwave power input to the i-type layer deposition chambers 210A and 210B is appropriately determined according to the flow rate of the source gas introduced into the deposition chamber, but with respect to the volume of the plasma formation space. 0.02-1W / cm ³ It is desirable that the range is a stable continuous wave with little fluctuation such as ripple. The frequency of the microwave power is preferably in the range of 0.5 to 10 GHz, and an industrial frequency of 2.45 GHz is preferably used.
[0087]
Furthermore, the microwave plasma CVD method of the present invention, the i-type layer deposition chambers 210A and 210B are supplied with high frequency power or DC power together with microwave power, with a bias electrode provided in the microwave plasma forming space. It is desirable to do. When high frequency power is applied, the power is 0.04 to 2 W / cm. ³ The frequency is preferably 1 to 100 MHz, and an industrial frequency of 13.56 MHz is preferably used. In addition, when DC power is input, it is preferable to input the DC power as high as possible within a range of 10 to 300 V in the direction in which the bias electrode side becomes positive within a range where abnormal discharge such as spark does not occur.
[0088]
Such microwave power is input to the film formation chamber 103, and preferably a high frequency or direct current power is input simultaneously to form a semiconductor film in the i-type layer film formation chamber 103 by microwave plasma CVD.
[0089]
(Formation of i-type semiconductor layer by high-frequency plasma CVD method)
In the apparatus of the present invention, the high-frequency power input to the i-type layer deposition chambers 103A, 103B, 103C, 203A, 203B, and 203C is appropriately determined according to the flow rate of the source gas introduced into the deposition chamber. 0.01 to 5 W / cm relative to the area of the generating electrode ² It is desirable that the range is a stable continuous wave with little fluctuation such as ripple. The frequency of the high-frequency power is preferably in the range of 1 to 100 MHz, and an industrial frequency of 13.56 MHz is preferably used, and the frequency variation is preferably within ± 2%.
[0090]
Furthermore, DC power may be supplied to the i-type layer deposition chambers 103A, 103B, 103C, 203A, 203B, and 203C of the apparatus of the present invention together with the high-frequency power. When applying DC power, it is preferable to apply DC power to the high-frequency discharge electrode as high as within a range in which abnormal discharge such as spark does not occur in the range of 10 to 200 V in the direction in which the discharge electrode becomes positive.
[0091]
Such high-frequency power is supplied to the film formation chambers 103A, 103B, 103C, 203A, 203B, and 203C, preferably DC power is supplied at the same time, and the semiconductor film is formed by high-frequency plasma CVD in the i-type layer film formation chamber 103C. Form.
[0092]
(Deposition conditions in film formation chamber 104C)
In the film formation chambers 104C and 204C, a p-type silicon-based non-single-crystal semiconductor layer is formed by plasma doping.
[0093]
The source gas introduced into the film formation chamber includes a gasifiable compound containing a group III atom in the periodic table in order to make the vicinity of the i-type non-single-crystal semiconductor layer surface p-type by plasma doping. .
[0094]
Effectively used as starting materials for introducing Group III atoms are specifically B for introducing B atoms. ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆ H ₁₂ , B ₆ H ₁₄ Boron hydride such as BF ₃ , BCl ₃ And the like. Besides this, AlCl ₃ , GaCl ₃ , InCl ₃ Etc. can also be mentioned. Especially B ₂ H ₆ , BF ₃ Is suitable. The source gas is H ₂ , D ₂ , He, Ne, Ar, Xe, Kr or the like may be included.
[0095]
Furthermore, the source gas may contain a gas containing a sufficient amount of Si atoms and a gas containing atoms such as C, O, and N to form an impurity doped layer having a desired film thickness by deposition. . In addition, as a gas containing such Si atoms, 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, Si ₂ D ₃ H ₃ Etc. As a gas containing C atoms, CH ₄ , CD ₄ , C _n H _{2n + 2} (N is an integer), C _n H _2n (N is an integer), C ₂ H ₂ , C ₆ H ₆ , CO ₂ As gas containing O atoms, CO, etc. may be O ₂ , CO, CO ₂ , NO, NO ₂ , N ₂ O, CH ₃ CH ₂ OH, CH ₃ OH or the like contains N atoms as N ₂ , NH ₃ , ND ₃ , NO, NO ₂ , N ₂ O etc. are mentioned.
[0096]
The discharge power is not particularly limited as long as glow discharge plasma such as low frequency, high frequency, and microwave is formed, but is preferably low frequency power of 5 to 500 kHz. The input power is 0.01 to 5 W / cm with respect to the area of the electrode. ² It is desirable that the range is a stable continuous wave with little fluctuation such as ripple. Furthermore, DC power may be supplied together with high-frequency power into the p-type layer deposition chambers 104C and 204C by plasma doping of the apparatus of the present invention.
[0097]
When applying DC power, it is preferable to apply DC power to the high-frequency discharge electrode as high as within a range in which abnormal discharge such as spark does not occur in the range of 10 to 200 V in the direction in which the discharge electrode becomes positive. Such discharge power is supplied to the film formation chambers 104C and 204C, and a semiconductor film is formed by plasma doping in the p-type layer film formation chambers 104C and 204C.
[0098]
While continuously moving the band-shaped substrate, the formation of the semiconductor layer as described above is continued at the same time in each of the film forming chambers 102 to 104, and a band-shaped substrate having a semiconductor laminated film formed on the surface is formed to have a certain length. The winding bobbin 109 in the winding chamber 105 is continuously wound.
[0099]
【Example】
Below, although the Example using each formation apparatus mentioned above using drawings is shown, this invention is not limited at all by these Examples.
[0100]
(Example 1)
In this example, the semiconductor laminated film continuous forming apparatus according to the present invention shown in Production Example 1 is used, and three structures made of nip junctions are provided on a base to overlap each other, thereby forming a nipnipnip structure silicon-based non-single crystal semiconductor. The laminated film was continuously formed. At that time, the i-type semiconductor layers forming the nip junctions were amorphous silicon germanium, amorphous silicon germanium, and amorphous silicon, respectively, from the bottom.
[0101]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure including the first nip junction are shown in Table 1, and the film formation conditions in the film formation chambers 102B to 104B for forming the structure including the second nip junction are as follows. Table 2 shows the film formation conditions in the film formation chambers 102C to 104C in which the structure including the third nip junction is formed.
FIG. 6 is a schematic cross-sectional view showing the layer structure of the solar cell fabricated in this example.
[0102]
Below, the formation method of this example is demonstrated according to a procedure.
(1) Fine irregularities laminated on a surface of a stainless steel plate made of SUS430BA (width 12 cm × length 200 m × thickness 0.15 mm) with a 500 nm Ag layer and an approximately 2 μm ZnO transparent conductive layer by sputtering. A belt-like substrate having a surface is wound around the bobbin 108 and set in the belt-like substrate unwinding chamber 101, and the belt-like substrate is passed through the film forming chambers 102 </ b> A to 104 </ b> C via the gas gates 106. The tension was applied to the extent that it did not relax. In addition, a bobbin wound with a sufficiently dried aramid paper protective film (Dupont Nomex (trade name), width 12 cm × length 200 m × thickness 0.05 mm) is set in the winding chamber 105 of the belt-shaped substrate. Then, the protective film is wound together with the belt-like substrate.
[0103]
(2) After setting the belt-like substrate, the chambers 101 to 105 are evacuated once with a pump that combines a rotary pump and a mechanical booster pump (not shown), and then He gas is introduced while evacuating to about 200 Pa of He. The inside of each film forming chamber was baked at about 350 ° C. in an atmosphere.
[0104]
(3) After heating and baking, each chamber 101 to 105 is evacuated once, and subsequently the film forming chambers 101 to 105 are exhausted with a pump that combines a rotary pump and a mechanical booster pump connected to each film forming chamber. Each gas gate 106 has H as a gate gas. ₂ Each source gas was introduced into each film formation chamber 102A to 104C at a predetermined flow rate. Then, by adjusting the opening degree of the throttle valve provided in the exhaust pipe of each of the chambers 101 to 105, the internal pressure of the unwinding chamber 101 and the winding chamber 105 of the belt-like substrate is set to 125 Pa, and the film forming chambers 102A, 103A, 104A. , 102B, 103B, 104B, 102C, 103C, and 104C were set to 130 Pa, 135 Pa, 130 Pa, 130 Pa, 135 Pa, 130 Pa, 130 Pa, 135 Pa, and 130 Pa, respectively.
[0105]
(4) When the pressure in each chamber is stabilized, the take-up bobbin 109 of the take-up chamber 105 of the belt-like substrate is rotated, and the belt-like substrate 107 is continuously moved at a constant speed of 100 cm / min in the direction from the film formation chamber 102A to 104C. Moved. Further, temperature control was performed by a temperature control device (not shown) provided in each of the film formation chambers 102A to 104C so that the moving belt-like substrate had a predetermined temperature in the film formation space of each film formation chamber. In the film forming chambers excluding 102B and 102C, the belt-like substrate was preheated to the same temperature as the film forming temperature for 10 seconds. In the film formation chambers 102B and 102C, the belt-shaped substrate was preheated to a temperature equal to or higher than the film formation temperature.
[0106]
(5) When the temperature of the belt-shaped substrate is stabilized, high-frequency power of 13.56 MHz is supplied from the parallel plate electrode to the film forming chambers 102A to 104C, and low-frequency power of 75 kHz is not shown from the parallel plate electrode to the film forming chamber 104C. It was turned on from the power supply through the matching device. By supplying the discharge power, the source gas in each of the film formation chambers 102A to 104C is turned into plasma, and a semiconductor film is formed on the surface of the band-shaped substrate that continuously moves in each film formation chamber, and nipnipnip continuously on the surface of the band-shaped substrate. A semiconductor laminated film having a structure was formed.
[0107]
(6) After starting to convey the belt-like substrate, it was continuously moved for 180 minutes, and during that time, a semiconductor laminated film was formed for 170 minutes. After the semiconductor laminated film is formed over about 170 m, the discharge power supply, the introduction of the source gas, and the heating of the band-shaped substrate and the film-forming chamber are stopped, and the film-forming chamber is purged. The apparatus was opened after the inside was sufficiently cooled, and the belt-like substrate wound around the bobbin 109 was taken out of the belt-like substrate winding chamber 105 to the outside of the device. Furthermore, the taken-out strip | belt-shaped base | substrate is continuously processed with the continuous modularization apparatus, and ITO (In) of 70 nm is formed on the whole surface as a transparent electrode on the semiconductor laminated film formed with the apparatus of this invention. ₂ O ₃ + SnO ₂ ) Three-layer tandem in which photovoltaic elements with different band gaps are stacked by forming a thin film, forming thin-line Ag electrodes at regular intervals as current collecting electrodes, and modularizing unit elements A solar cell module having a size of 35 cm × 35 cm constituted by a solar cell was continuously produced.
[0108]
(Comparative Example 1)
This example is different from Example 1 in that the band-shaped substrate was not preheated in the n-type semiconductor layer deposition chambers 102B and 102C by the high-frequency plasma CVD method.
The other points were the same as in Example 1.
[0109]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure formed of the first nip junction were the same as those in Table 1, as in Example 1. The film formation conditions in the film formation chambers 102B to 104B for forming the structure composed of the second nip junction are shown in Table 4, and the film formation conditions in the film formation chambers 102C to 104C for forming the structure composed of the third nip junction are as follows. Table 5 shows.
[0110]
Below, the evaluation result performed with respect to the produced solar cell module is demonstrated.
AM1.5 (100mW / cm ² The photoelectric conversion characteristics were evaluated under the simulated sunlight irradiation. The numerical value obtained by normalizing the average value of the photoelectric conversion efficiency of Example 1 with the average value of the photoelectric conversion efficiency of Comparative Example 1 was as good as 1.20. In addition, the variation in the photoelectric conversion efficiency between modules was as large as ± 5% in Comparative Example 1 while that in Example 1 was within ± 2%.
[0111]
(Example 2)
This example is different from Example 1 in that the i-type semiconductor layer formed in the film formation chamber 103B is replaced with amorphous silicon.
[0112]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure composed of the first nip junction were the same as those in Table 1, as in Example 1. Table 6 shows the film formation conditions in the film formation chambers 102B to 104B in which the structure including the second nip junction is formed. The film formation conditions in the film formation chambers 102C to 104C for forming the structure formed of the third nip junction were the same as those in Table 3 as in Example 1.
The other points were the same as in Example 1.
[0113]
(Comparative Example 2)
This example is different from Example 2 in that the band-shaped substrate was not preheated in the n-type semiconductor layer deposition chambers 102B and 102C by the high-frequency plasma CVD method.
[0114]
The film formation conditions in the film formation chambers 102 </ b> A to 104 </ b> A for forming the structure including the first nip junction were the same as those in Table 1 as in Comparative Example 1. Table 7 shows the film formation conditions in the film formation chambers 102B to 104B in which the structure including the second nip junction is formed. The film formation conditions in the film formation chambers 102 </ b> C to 104 </ b> C for forming the structure including the third nip junction were the same as those in Table 5 as in Comparative Example 1.
The other points were the same as in Example 2.
[0115]
Below, the evaluation result performed with respect to the produced solar cell module is demonstrated.
AM1.5 (100mW / cm ² The photoelectric conversion characteristics were evaluated under the simulated sunlight irradiation. The numerical value obtained by normalizing the average value of the photoelectric conversion efficiency of Example 2 with the average value of the photoelectric conversion efficiency of Comparative Example 2 was as good as 1.15. Further, the variation in the photoelectric conversion efficiency between modules was as large as ± 5% in Comparative Example 2 while that in Example 2 was within ± 2%.
[0116]
(Example 3)
This example is different from Example 1 in that the i-type semiconductor layer formed in the film formation chamber 103C is replaced with amorphous silicon carbide.
[0117]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure composed of the first nip junction were the same as those in Table 1, as in Example 1. The film formation conditions in the film formation chambers 102B to 104B for forming the structure including the second nip junction were also the same as those in Table 2 as in Example 1. The film formation conditions in the film formation chambers 102C to 104C for forming the structure including the third nip junction were the conditions shown in Table 8.
The other points were the same as in Example 1.
[0118]
About the produced solar cell module, AM1.5 (100 mW / cm ² ) Was evaluated under simulated sunlight irradiation. As a result, the numerical value obtained by normalizing the average value of the photoelectric conversion efficiency of the solar cell module according to this example with the average value of the photoelectric conversion efficiency of the conventional solar cell module was as good as 1.20. Also, the variation in the photoelectric conversion efficiency between modules was as large as ± 5% in the prior art, while this example was within ± 2%.
[0119]
However, the conventional solar cell module used in comparison with Example 3 does not heat the deposited film together with the substrate before forming the n-type semiconductor layer in the structure composed of the second and third nip junctions. Refers to a solar cell module.
[0120]
(Example 4)
This example is different from Example 2 in that the i-type semiconductor layer formed in the film formation chamber 103C is replaced with amorphous silicon carbide.
[0121]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure including the first nip junction were the same as those in Table 1 as in Example 2. The film formation conditions in the film formation chambers 102B to 104B for forming the structure including the second nip junction were also the same as those in Table 6 as in Example 2. The film formation conditions in the film formation chambers 102C to 104C for forming the structure including the third nip junction were the conditions shown in Table 8.
The other points were the same as in Example 2.
[0122]
About the produced solar cell module, AM1.5 (100 mW / cm ² ) Was evaluated under simulated sunlight irradiation. As a result, the numerical value obtained by normalizing the average value of the photoelectric conversion efficiency of the solar cell module according to this example with the average value of the photoelectric conversion efficiency of the conventional solar cell module was 1.20. Also, the variation in the photoelectric conversion efficiency between modules was as large as ± 5% in the prior art, while this example was within ± 2%.
[0123]
However, the conventional solar cell module used in comparison with Example 4 does not heat the deposited film together with the substrate before forming the n-type semiconductor layer in the structure formed of the second and third nip junctions. Refers to a solar cell module.
[0124]
(Example 5)
The present embodiment is different from the first embodiment in that the forming apparatus shown in the apparatus example 2 is used instead of the forming apparatus shown in the apparatus example 1.
Further, when the forming apparatus shown in the apparatus example 2 is used, the following five items are different from those in the first embodiment.
[0125]
(A) Of the three film forming chambers 212, 213, and 214 that form the n-type semiconductor layer in the structure formed of the second nip junction, in the film forming chamber 212, a high-frequency power is not applied, and only the heating is performed. An n-type semiconductor layer was formed in the film formation chambers 213 and 214 by a high-frequency plasma CVD method as a heating chamber.
[0126]
(B) Only in the structure composed of the first and second nip junctions, after the i-type semiconductor layer is formed by the high-frequency plasma CVD method, the i-type semiconductor layer is formed by the microwave plasma CVD method in the film forming chambers 210A and 210B. Furthermore, before the p-type semiconductor layer is formed, the surface of the i-type semiconductor layer is formed in the film formation chambers 211A and 211B by the high-frequency plasma CVD method.
[0127]
(C) In the film forming chambers 210A and 210B, three film forming chambers are used for forming the i-type semiconductor layer, and the length of each film forming chamber inside the 210A and 210B in the moving direction of the band-shaped substrate is used. The length was about 20 cm, but by providing a shield plate (also used as a plasma leakage guard) of a certain length between the surface of the belt-shaped substrate and the plasma, the length of the semiconductor layer formation region in the moving direction of the belt-shaped substrate was reduced. Adjusted.
[0128]
(D) In the film formation chambers 210A and 210B, a microwave power of 2.45 GHz is applied from the microwave introduction window provided on one side wall of each film formation chamber to the band-shaped substrate in front of the microwave introduction window. High frequency power of 13.56 MHz was input from a power source (not shown) through a matching device from rod-shaped bias electrodes arranged in parallel.
[0129]
(E) The preheating temperature of the film formation chamber 202C in which the n-type semiconductor layer of the structure including the third nip junction is formed is higher than the film formation temperature.
[0130]
The film formation conditions in the film formation chambers 102A to 104A for forming the structure including the first nip junction were the conditions shown in Table 9. The film formation conditions in the film formation chambers 102B to 104B for forming the structure including the second nip junction were the conditions shown in Table 10. The film formation conditions in the film formation chambers 102C to 104C for forming the structure formed of the third nip junction were the same as those in Table 3 as in Example 1.
[0131]
FIG. 7 is a schematic cross-sectional view showing the layer structure of the solar cell fabricated in this example.
The other points were the same as in Example 1.
[0132]
(Comparative Example 5)
In this example, preheating of the belt-shaped substrate performed in the film formation chamber 212 is not performed among the three film formation chambers 212, 213, and 214 that form the n-type semiconductor layer of the structure including the second nip junction. This is different from Example 5.
The other points were the same as in Example 5.
[0133]
Below, the evaluation result performed with respect to the produced solar cell module is demonstrated.
AM1.5 (100mW / cm ² The photoelectric conversion characteristics were evaluated under the simulated sunlight irradiation. The numerical value obtained by normalizing the average photoelectric conversion efficiency of Example 2 with the average photoelectric conversion efficiency of Comparative Example 2 was as good as 1.22. Further, the variation in the photoelectric conversion efficiency between the modules was as large as ± 5% in Comparative Example 2 while that in Example 5 was within ± 1.5%.
[0134]
[Table 1]

[0135]
[Table 2]

[0136]
[Table 3]

[0137]
[Table 4]

[0138]
[Table 5]

[0139]
[Table 6]

[0140]
[Table 7]

[0141]
[Table 8]

[0142]
[Table 9]

[0143]
[Table 10]

[0144]
【The invention's effect】
As described above, according to the present invention, the photoelectric conversion efficiency is high and the variation in photoelectric conversion efficiency between modules is small. Method for forming photovoltaic element Is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a forming apparatus according to the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of the forming apparatus according to the present invention.
FIG. 3 is a schematic cross-sectional view showing an example of a film forming chamber by a microwave plasma CVD method that constitutes a forming apparatus according to the present invention.
FIG. 4 is a schematic cross-sectional view showing an example of a film forming chamber by a high-frequency plasma CVD method that constitutes a forming apparatus according to the present invention.
FIG. 5 is a schematic cross-sectional view showing another example of a film forming chamber by a high-frequency plasma CVD method that constitutes the forming apparatus according to the present invention.
FIG. 6 is a schematic cross-sectional view showing an example of a layer configuration of a photovoltaic element according to the present invention.
FIG. 7 is a schematic cross-sectional view showing another example of the layer configuration of the photovoltaic element according to the present invention.
[Explanation of symbols]
101, 201 Unwinding chamber for the strip-shaped substrate,
102A, 102B, 102C, 202A, 202B, 202C n-type semiconductor layer deposition chamber by high-frequency plasma CVD method,
103A, 103B, 103C, 203A, 203B, 203C A chamber for forming an i-type semiconductor layer by a high-frequency plasma CVD method,
104A, 104B, 104C, 204A, 204B A p-type semiconductor layer deposition chamber formed by high-frequency plasma CVD,
A deposition chamber for a p-type semiconductor layer by 204C plasma doping;
105, 205 Winding chamber for the belt-shaped substrate,
106, 206, 303, 304, 403, 503, 504 Gas gate,
107, 207, 301, 401, 501 strip substrate,
108, 208 Unwinding bobbin of the belt-shaped substrate,
109, 209 A winding bobbin of a belt-shaped substrate,
210A, 210B A chamber for forming an i-type semiconductor layer by microwave plasma CVD,
211A, 211B A chamber for forming an i-type semiconductor layer by a high-frequency plasma CVD method,
212, 213, 214 An n-type semiconductor layer deposition chamber formed by a high-frequency plasma CVD method,
302, 402, 502A, 502B, 502C vacuum vessel,
305 discharge chamber unit,
306, 307, 308 Deposition chamber,
309, 407, 507A, 507B, 507C source gas introduction pipe,
312 pressure measuring tube,
315, 316, 317 bias electrode,
318, 319, 320 microwave introduction window,
321, 322, 323, 324 perforated partition plate,
325, 326, 408, 508A, 508B, 508C exhaust pipe,
327 roughing exhaust pipe,
328 powder receiving plate,
329, 411, 511 Plasma leak guard,
330 Deposition chamber temperature control device,
331, 412, 512A, 512B, 512C lid,
332, 413, 414, 513A, 514A, 513B, 514B, 513C, 514C lamp heater,
333, 334, 335 substrate temperature control device,
336, 337, 338, 339, 415, 416, 515A, 516A, 515B, 516B, 515C, 516C thermocouple,
340, 417, 517A, 517B, 517C reflector,
341, 345, 418, 518 support rollers,
442, 542 separation passage,
343, 344, 443, 444, 543, 544 gate gas introduction pipe,
405, 505A, 505B, 505C discharge chamber,
406, 506A, 506B, 506C discharge electrodes,
409, 509A, 509B, 509C Block heater,
410, 510A, 510B, 510C discharge chamber external exhaust port,
601, 701 substrate,
602A, 602B, 602C, 702A, 702B, 702C n-type semiconductor layer by high frequency plasma CVD method,
603A, 603B, 603C, 703A, 703B, 703C, 708A, 708B i-type semiconductor layer by high-frequency plasma CVD method,
604A, 604B, 604C, 704A, 704B p-type semiconductor layer by high-frequency plasma CVD method,
604C, 704C p-type semiconductor layer by plasma doping,
707A, 707B i-type semiconductor layer by microwave plasma CVD method,
605, 705 transparent conductive film,
606, 706 Current collecting electrode.

Claims (1)

When p-type semiconductor layer is p, i-type semiconductor layer is i, and n-type semiconductor layer is n,
In a photovoltaic device in which at least two or more structures composed of nip junctions laminated in the order of n, i, and p are provided on a substrate,
When the lower layer of the reverse junction where the structures are in contact is p ′ and the upper layer is n ′,
Between the step of forming the p ′ and the step of forming the n ′,
A method of forming a photovoltaic device, comprising the step of heat-treating the substrate formed up to p ′ at a temperature higher than the substrate temperature when forming n ′.

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