JP2004260013A - Photoelectric converter and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize integrated structure and its manufacturing method capable of simplifying the accuracy of working processes and preventing the generation of lateral leakage. <P>SOLUTION: In a photoelectric converter, a plurality of semiconductor elements have integrated structure in which adjacent semiconductor elements are connected in series with a conductive material 110. These semiconductor elements are mutually separated by a 1st separation groove 105 for separating the semiconductor elements from a rear electrode 104 up to a surface electrode 102, and each of those semiconductor elements is separated into a 1st area and a 2nd by a 2nd separation groove 106 for separating the semiconductor element from the rear electrode 104 up to a semiconductor multilayer film 103. The serial connection of adjacent semiconductor elements is realized by connecting the rear electrode 104 in the 1st area of one semiconductor element to the surface electrode 102 in the 2nd area of the other semiconductor element adjacent to one semiconductor element by the conductive material 110. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an integrated structure of a photoelectric conversion device represented by a solar cell and a method for manufacturing the same.
[0002]
[Prior art and its problems]
In a super-straight thin-film solar cell using a transparent conductive film formed on a light-transmitting substrate for the front electrode, low current density and high voltage characteristics are required to minimize the effect of the series resistance component of the transparent conductive film. It is common to use the resulting integrated structure. This is shown in FIG. 2 along with the process. Here, in the figure, 201 is a translucent substrate, 202 is a front electrode, 203 is a first separation groove, 204 is a semiconductor multilayer film, 205 is a connection groove, 206 is a back electrode, and 207 is a second separation groove. . The conventional integrated structure includes a first separation groove for separating a front electrode, a second separation groove for separating a back electrode, and a connection groove for enabling series connection with an adjacent element.
[0003]
Here, it is to be noted that a characteristic part in relation to the present invention is described in advance. In the conventional integrated structure, each layer of the semiconductor multilayer film forming the photovoltaic region extends to the side wall of the connection groove. Is characterized by being in contact with a conductive connecting material such as a metal existing in the above. This indicates that each semiconductor layer is short-circuited with the back electrode electrically connected to the connection groove in terms of a circuit, but actually, compared to the magnitude of the photocurrent generated by the semiconductor element, The leak current that causes each semiconductor layer to have a lateral leak path is so small that it can be neglected because the resistance of each semiconductor layer is sufficiently large, and no particularly fatal problem has occurred in the conventional integrated structure.
[0004]
By the way, as shown in FIG. 2, the integrated structure at the beginning of the invention is to form a front electrode 202 as a transparent conductive film on a light-transmitting substrate 201 and pattern it (forming a first separation groove 203). ), Followed by formation of the semiconductor multilayer film 204, patterning thereof (formation of the connection groove 205), formation of the back electrode 206, and patterning thereof (formation of the second separation groove 207) in this order. Was. At this time, a laser scribe technique or a mask etching technique was used as a patterning technique.
[0005]
However, in the process of performing patterning processing every time a film is formed, a cleaning step is required for each patterning processing step, which not only complicates the process and complicates the process, but also removes foreign substances generated during patterning processing in the cleaning step. There is a problem that leakage cannot be completed, or a residue or the like adheres in the cleaning process itself, so that a leak in the vertical direction (layer thickness direction) of the semiconductor multilayer film easily occurs and the yield is easily lowered.
[0006]
Therefore, in order to solve these problems, an element / process separation process of patterning after forming a front electrode / semiconductor multilayer film / back electrode (after forming an element structure) has been developed (see Patent Documents 1 and 2). . This process is shown in FIG. Here, in the figure, 301 is a translucent substrate, 302 is a front electrode, 303 is a semiconductor multilayer film, 304 is a back electrode, 305 is a first separation groove, 306 is a connection groove, 307 is an insulator, and 308 is conductive. The material 309 is a second separation groove. In this process, the element formation step and the patterning processing step are separated, so that the above-described cleaning step for each film formation is not required, and at the same time, foreign substances due to processing, residues due to cleaning, and the like are present in the film. The possibility of being taken in can be eliminated.
[0007]
However, even in these prior arts, there was no difference in the structure in which the semiconductor layer forming the photovoltaic region was in contact with the side wall of the connection groove. Is not formed, but as described below, the structure is not such that the short circuit problem in the case of a multi-junction type can be avoided). Another problem is that it is very difficult to control the depth of laser processing when forming the separation groove (for example, only the back electrode is separated and the semiconductor layer immediately below is not separated, only the insulating coat layer is separated). Do not separate the back electrode directly below).
[0008]
By the way, in order to increase the efficiency of a thin-film solar cell, it is very effective to use a multi-junction solar cell structure such as a tandem type in place of a single junction type which has been generally used in the past. However, in the integration of a multi-junction solar cell, a new problem that does not occur in the case of the single-junction solar cell is newly generated. This is due to the fact that the reverse junction is inevitably generated in the multi-junction type.
[0009]
For example, a tandem-type thin-film silicon solar cell having an a-Si: H (pin) / μc-Si: H (pin) configuration as a semiconductor multilayer film in which an amorphous silicon element is used as a top cell and a microcrystalline silicon element is used as a bottom cell. For example, the reverse junction occurs in a region where a-Si: H (n) and μc-Si: H (p) are in contact with each other. By the way, in this reverse junction, the junction characteristics are required to be tunnel junction characteristics (here, the “tunnel junction characteristics” are not only the characteristics of the original tunnel junction but also the characteristics of the tunnel junction. Defining the properties of a junction, including junctions with junction properties: a junction of poor quality (that is, prone to recombination) may be sufficient, even if it is not really a pure tunnel junction ). In other words, the reverse junction needs to exhibit good ohmic properties and the same junction characteristics in a voltage range that can be used without problems as a solar cell (otherwise, the recombination of carriers at the reverse junction becomes insufficient (the reverse junction becomes insufficient). This is because the current flow is rate-determined at the junction and the element characteristics are degraded).
[0010]
In addition, as the combination of the material of the reverse junction, a-Si: H (n) / a-Si: H (a) other than the above-mentioned a-Si: H (n) / μc-Si: H (p) p), .mu.c-Si: H (n) /. mu.c-Si: H (p), .mu.c-Si: H (n) / a-Si: H (p), etc., to control film forming conditions. By doing so, any of them can be realized. The essence of the above discussion does not change even when the nip type is used in the reverse order.
[0011]
Now, the reverse junction having this tunnel junction characteristic has a very high impurity concentration (typically 1 × 10 4) in order to realize the tunnel junction characteristic. ¹⁸ / Cm ³ Above). Therefore, the carrier concentration is also very high. Therefore, a current is very easy to flow in the joining surface direction of the reverse joining portion (the horizontal direction when the layer thickness direction is the vertical direction). In other words, in a tandem type (including a multi-junction type), if the conventional integrated structure is adopted as it is, the reverse junction will be connected to the connection groove, so that the reverse junction will function as a lateral leak path, and This causes a problem that the reverse junction, the back electrode, and the reverse junction are short-circuited (that is, the top cell and the bottom cell are short-circuited, respectively). This problem situation is shown in FIGS. The photoelectric conversion device having the integrated structure shown in FIGS. 4 and 5 is an example in which the semiconductor multilayer film in FIGS. 2 and 3 is constituted by a first semiconductor bonding layer and a second semiconductor bonding layer. It is. Here, 204a and 303a indicate a first semiconductor bonding layer as a top cell, 204b and 303b indicate a second semiconductor bonding layer as a bottom cell, and other reference numerals are the same as those in FIGS. The reverse junction in question is formed between the first semiconductor bonding layer 204a (303a) and the second semiconductor bonding layer 204b (303b).
[0012]
This problem also occurs, for example, when the top cell and the bottom cell are in ohmic contact with each other by forming a thin metal layer or a transparent conductive film layer as a conductive intermediate layer instead of forming a reverse junction between the top cell and the bottom cell. In this case, a thin metal layer or a transparent conductive film layer serves as a horizontal leak path.
[0013]
Regarding this problem, for example, a method of oxidizing the connection groove wall surface during the formation of the connection groove has been conventionally known (see Patent Document 3). However, in this method, it is very difficult to prevent leakage with high reliability compared to a method in which an insulating film such as an oxide film is separately formed, and when a transparent conductive film such as a metal oxide is used for the intermediate layer, the target is already exposed. Since it is an oxide, it is very difficult to increase its resistance, and a more reliable and complete leakage prevention measure has been required. It is not a process separation type).
[0014]
Other prior applications of the element / process separation type include, for example, Patent Documents 4, 5, and 6, all of which relate to a substrate type in which light enters from a film surface from a direction opposite to a substrate. In addition, the series connection structure in Patent Document 4 is not necessarily highly reliable and is not easily accurate, and in Patent Documents 5 and 6, the connection groove and the semiconductor layer forming the photovoltaic region are different. There is no electrical isolation.
[0015]
[Patent Document 1]
Japanese Patent Publication No. 5-82993
[Patent Document 2]
JP-A-3-250771
[Patent Document 3]
Japanese Patent Publication No. 7-114292
[Patent Document 4]
JP-A-9-266320
[Patent Document 5]
JP 2000-252508 A
[Patent Document 6]
JP 2001-7359A
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention makes it possible to simplify the patterning process accurately (thus reducing the cost) while taking advantage of the element / processing separation process, and to provide a reverse junction portion or the like in a semiconductor multilayer film. An object of the present invention is to realize an integrated structure and a manufacturing method of a photoelectric conversion device that can prevent a lateral leak even if a conductive intermediate layer is present.
[0017]
That is, the photoelectric conversion device of the present invention includes a plurality of semiconductor elements in which a front electrode, a semiconductor multilayer film having at least one or more semiconductor junctions, and a back electrode are formed in this order on a light-transmitting substrate. In a photoelectric conversion device having an integrated structure in which adjacent semiconductor elements are connected in series, the plurality of semiconductor elements are separated from each other by a first separation groove separating a back electrode from a front electrode, Each of the plurality of semiconductor elements is separated into a first region and a second region by a second separation groove separating the back electrode from the semiconductor multilayer film, and a series connection between adjacent elements of the plurality of semiconductor elements. The connection is made by a conductive material between the back electrode in the first region of one semiconductor element and the front electrode in the second region of the other semiconductor element adjacent to the one semiconductor element. Characterized in that it is realized by being connected Te.
[0018]
Further, the semiconductor element is covered with an insulating film, and the connection of the back electrode of the one semiconductor element and the front electrode of the other semiconductor element by the conductive material is performed by the first semiconductor element. A first connection port formed in the insulating film in a region of the semiconductor device, and a second connection region of the other semiconductor device adjacent to the one semiconductor device, wherein the insulating film, the back electrode, and the semiconductor This is realized through a second connection port formed by a connection groove penetrating the multilayer film and reaching the front electrode, and the first separation groove and the second separation groove are covered with the insulating film. It is characterized by being done.
[0019]
The semiconductor film may include a plurality of semiconductor bonding layers, and a metal layer or a transparent conductive layer is interposed between at least one semiconductor bonding layer.
[0020]
Further, the metal layer is made of an alloy material containing silicon.
[0021]
Further, the transparent conductive layer is made of a metal oxide containing at least one of indium oxide, indium-tin oxide, tin oxide, and zinc oxide.
[0022]
Further, the insulating film is made of a material containing at least one of silicon oxide, silicon carbide, and silicon nitride.
[0023]
Further, the insulating film is made of a material containing at least one of a metal oxide and a metal nitride.
[0024]
Further, the insulating film is made of a material containing at least one of diamond and diamond-like carbon.
[0025]
Further, the insulating film is made of a resin material.
[0026]
The conductive material is at least one of a metal film, a metal wire, a metal foil, and a conductive paste.
[0027]
In the manufacturing method of the present invention, a first electrode is formed by sequentially laminating a front electrode, a semiconductor multilayer film having at least one or more semiconductor junctions, and a back electrode on a translucent substrate to form a first laminate. A second step of separating the first stacked body into a plurality of elements by a first separation groove; and a front electrode, a semiconductor multilayer film, and a back surface constituting each of the plurality of elements by a second separation groove. A third step of separating a laminated body portion composed of a semiconductor multilayer film and a back electrode among the electrodes into at least two regions, a connection region and a power generation region; and at least the back electrode, the first separation groove, and the A fourth step of laminating an insulating film so as to cover a region where the two isolation grooves are present, and a fifth step of forming a first connection port penetrating the insulating film and reaching the back electrode in the power generation region. Reaching the front electrode with respect to the connection region. A sixth step of forming a second connection port comprising a connection groove, a back electrode located at the first connection port in one of the separated elements, and the one electrode separated by the first separation groove; By electrically connecting the element and the front electrode located at the second connection port of the adjacent other element by a conductive material, and by sequentially repeating this connection structure for further adjacent elements, A seventh step of connecting a plurality of elements in series.
[0028]
Further, at least one of the first separation groove and the second separation is formed by a laser scribe method or an etching method.
[0029]
The first connection port is formed by a mask patterning method or a laser scribe method.
[0030]
Further, the seventh step is characterized by performing a combination of a metal film forming method and a mask patterning method or an etching method.
[0031]
Further, at least one of a metal film, a metal wire, a metal foil, and a conductive paste is used as the conductive material in the seventh step.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a photoelectric conversion device according to the present invention will be described in detail with reference to the drawings.
[0033]
<Configuration of photoelectric conversion device>
FIG. 1 shows an example in which the present invention is applied to a tandem type thin-film Si (silicon) solar cell element together with a process thereof. Here, in the figure, 101 is a translucent substrate, 102 is a front electrode, 103 is a semiconductor multilayer film, 103a is a first semiconductor bonding layer, 103b is a second semiconductor bonding layer, 104 is a back electrode, and 105 is a second electrode. 1 is a separation groove, 106 is a second separation groove, 107 is an insulating film, 108 is a first connection port, 109 is a connection port and a second connection port, 110 is a conductive material, and 111 is a third separation groove. It is.
[0034]
As shown in FIG. 1E, the photoelectric conversion device of the present invention includes a front electrode 102, a semiconductor multilayer film 103 having at least one or more semiconductor junctions (103a, 103b) on a light-transmitting substrate 101, and a back surface. A plurality of semiconductor elements in which the electrodes 104 are formed in this order have an integrated structure in which adjacent semiconductor elements are connected in series by a conductive material 110. The plurality of semiconductor elements are separated from each other by a first separation groove 105 separating to the front electrode 102, and each of the plurality of semiconductor elements is separated into a first region by a second separation groove 106 separating from the back electrode 104 to the semiconductor multilayer film 103. And a second region, and the series connection between adjacent ones of the plurality of semiconductor devices is connected to the back electrode 104 in the first region of one of the semiconductor devices. One of the semiconductor element and the front electrodes 102 in the second region of the other adjacent semiconductor elements are realized by being connected by the conductive material 110.
[0035]
Further, the semiconductor element is covered with an insulating film 107, and the connection of the back electrode 104 of one semiconductor element and the front electrode 102 of the other semiconductor element by the conductive material 110 is performed in the first region of one semiconductor element. A first connection port 108 formed in the insulating film 107 in the inside and a second region of the other semiconductor element adjacent to one semiconductor element are provided in the insulating film 107, the back electrode 104, and the semiconductor multilayer film 103. Through a second connection port 109 formed by a connection groove reaching the front electrode 102, and the first separation groove 105 and the second separation groove 106 are covered with an insulating film 107. ing.
[0036]
<Method for manufacturing photoelectric conversion device>
The photoelectric conversion device thus configured is manufactured by the following steps. That is, a first step of sequentially laminating a front electrode 102, a semiconductor multilayer film 103 having at least one or more semiconductor junctions, and a back electrode 104 on a translucent substrate 101 to form a first laminated body A second step of separating the first stacked body into a plurality of elements by the first separation groove; and a front electrode 102, a semiconductor multilayer film 103, and a back electrode constituting each of the plurality of elements by the second separation groove. 104, a third step of separating a stacked body portion composed of the semiconductor multilayer film 103 and the back electrode 104 into at least two regions, a connection region and a power generation region, and at least a back electrode 104, a first separation groove 105, A fourth step of laminating the insulating film 107 so as to cover a region where the second isolation groove 106 is present, and a first connection port that reaches the back electrode 104 through the insulating film 107 in the power generation region. 1 A fifth step of forming a second connection port 109 including a connection groove reaching the front electrode 102 with respect to the connection region; and a fifth step of forming the second connection port 109 with the connection region. The back electrode 104 located at the first connection port 109 and the front electrode 102 located at the second connection port 109 of one element adjacent to the other element separated by the first separation groove 105 are made of a conductive material. A seventh step of connecting a plurality of devices in series by electrically connecting the devices 110 and sequentially repeating the connection structure with respect to further adjacent devices.
[0037]
Next, a specific manufacturing method of the present invention will be described.
[0038]
<Element formation (see FIG. 1A)>
First, a light-transmitting substrate 101 is prepared. Here, as the light-transmitting substrate 101, a plate material or a film material made of glass, plastic, resin, or the like can be used.
[0039]
Next, the front electrode 102 is formed over the light-transmitting substrate 101. As the front electrode 102, a known oxide transparent conductive film can be used. Specifically, tin oxide SnO ₂ For example, a material such as ITO which is indium-tin oxide and ZnO which is a zinc oxide can be used. The transparent conductive film is made of SiH when a Si film is formed on the film later. ₄ And H ₂ Therefore, it is desirable to form a ZnO film having excellent reduction resistance at least as a final surface, since it will be exposed to an active hydrogen gas atmosphere caused by the use of a ZnO film. As the film forming method, a known technique such as a CVD method, an evaporation method, an ion plating method, a sputtering method, a spray method, and a sol-gel method can be used. The thickness of the transparent conductive film is adjusted in the range of about 60 to 600 nm in consideration of the antireflection effect and the reduction in resistance. As a guide for lowering the resistance, it is desirable to set the sheet resistance to about 10Ω / □ or less.
[0040]
Next, the semiconductor multilayer film 103 is formed. The semiconductor multilayer film 103 includes a first semiconductor bonding layer 103a and a second semiconductor bonding layer 103b.
[0041]
First, a first semiconductor bonding layer 103a is formed on the front electrode 102. The semiconductor bonding layer 103a is a pin junction (not shown) in which a p-type layer, an i-type layer, and an n-type layer are sequentially stacked. As the manufacturing method, in addition to the known PECVD method and Cat-CVD method, the present inventors have already disclosed Cats disclosed in Japanese Patent Application Nos. 2000-130858, 2001-29331, and 2002-38686. -A PECVD method can be used.
[0042]
Here, as the p-type layer, a hydrogenated amorphous silicon film or a crystalline silicon film containing a microcrystalline silicon phase can be used. The thickness is adjusted in the range of about 2 to 100 nm according to the material. 1 × 10 for doping element concentration ¹⁸ ~ 1 × 10 ²¹ / Cm ³ As a degree, substantially p ⁺ Type. The SiH used for film formation ₄ , H ₂ And B as a doping gas ₂ H ₆ CH in addition to gases such as ₄ If an appropriate amount of gas containing C (carbon) such as _x C _1-x A film is obtained, which is very effective for forming a window layer with small light absorption loss, and is also effective for reducing a dark current component for improving an open circuit voltage. A similar effect can be obtained by mixing an appropriate amount of a gas containing O (oxygen) or a gas containing N (nitrogen) in addition to C.
[0043]
For the i-type layer which is a photoactive layer, a hydrogenated amorphous silicon film is used, and the film thickness is adjusted in the range of about 0.1 to 0.5 μm. In practice, a non-doped film usually shows a slight n-type characteristic, and in this case, it can be adjusted to be substantially i-type by slightly including a p-type doping element. Note that, for the purpose of fine adjustment of the internal electric field strength distribution, n ⁻ Type or p ⁻ It may be a type.
[0044]
As the n-type layer, a hydrogenated amorphous silicon film or a crystalline silicon film containing a microcrystalline silicon phase can be used. The thickness is adjusted in the range of about 2 to 100 nm depending on the material. 1 × 10 for doping element concentration ¹⁸ -10 ²¹ / Cm ³ The degree is substantially n ⁺ Type. The SiH used for film formation ₄ , H ₂ And the doping gas PH ₃ CH in addition to gases such as ₄ If an appropriate amount of gas containing C (carbon) such as _x C _1-x A film can be obtained, and a film with little light absorption loss can be formed, and it is also effective in reducing a dark current component for improving an open circuit voltage. A similar effect can be obtained by mixing an appropriate amount of a gas containing O (oxygen) or a gas containing N (nitrogen) in addition to C.
[0045]
In order to further improve the junction characteristics, a substantially i-type non-single-crystal Si layer or a non-single-crystal Si layer is provided between the p-type layer and the photoactive layer or between the photoactive layer and the n-type layer. _x C _1-x Layers may be inserted. At this time, the thickness of the insertion layer is about 0.5 to 50 nm.
[0046]
Here, in order to realize good tunnel junction characteristics at the junction between the first semiconductor bonding layer 103a and the second semiconductor bonding layer 103b described below (that is, to realize ohmic contact-like electrical connection characteristics). For this reason, in the n-type layer included in the first semiconductor bonding layer 103a and the p-type layer included in the second semiconductor bonding layer 103b to be described later, the crystallization ratio is increased at least at a portion where they are in contact with each other. Is desirable.
[0047]
In order to realize ohmic contact electrical connection characteristics between the first semiconductor bonding layer 103a and the second semiconductor bonding layer 103b, a transparent conductive film, a thin metal layer, or a thin silicide layer (silicon and metal Alloy layer) as a conductive intermediate layer. Here, as the transparent conductive film, SnO2 which is a tin oxide, ITO which is an indium-tin oxide, ZnO which is a zinc oxide, or the like can be used. Here, when a transparent conductive film is used, an optical effect (reflection and transmission characteristics) can be introduced by the presence of the transparent conductive film, and therefore, the use of a transparent conductive film is very excellent in terms of high efficiency. That is, by adjusting the thickness of the transparent conductive film, short-wavelength light is reflected by the transparent conductive film and re-enters the first semiconductor bonding layer 103a preferentially, and long-wavelength light has the same antireflection effect. According to the principle, the semiconductor layer can be preferentially confined in the second semiconductor bonding layer 103b, and more efficient photoelectric conversion of light energy becomes possible. In the case where a silicide layer is used, an effect can be expected that an ohmic contact between the first semiconductor bonding layer 103a and the second semiconductor bonding layer 103b can be more reliably and simply realized with a high yield.
[0048]
Next, a second semiconductor bonding layer 103b is formed on the first semiconductor bonding layer 103a. The semiconductor bonding layer 103b is a pin junction (not shown) in which a p-type layer, an i-type layer, and an n-type layer are sequentially stacked. As the manufacturing method, in addition to the known PECVD method and Cat-CVD method, the present inventors have already disclosed Cats disclosed in Japanese Patent Application Nos. 2000-130858, 2001-29331, and 2002-38686. -A PECVD method can be used.
[0049]
Here, as the p-type layer, a hydrogenated amorphous silicon film or a crystalline silicon film containing a microcrystalline silicon phase can be used. The thickness is adjusted in the range of about 2 to 100 nm depending on the material. 1 × 10 for doping element concentration ¹⁸ ~ 110 ²¹ / Cm ³ As a degree, substantially p ⁺ Type. Note that the SiH used for film formation is ₄ , H ₂ And the doping gas B ₂ H ₆ CH in addition to gases such as ₄ If an appropriate amount of gas containing C (carbon) such as _x C _1-x A film is obtained, which is very effective for forming a window layer with small light absorption loss, and is also effective for reducing a dark current component for improving an open circuit voltage. A similar effect can be obtained by mixing an appropriate amount of a gas containing O (oxygen) or a gas containing N (nitrogen) in addition to C.
[0050]
For the i-type layer which is a photoactive layer, a crystalline silicon film typified by a microcrystalline silicon film is used, and the thickness is adjusted in a range of about 1 to 3 μm. In practice, a non-doped film usually shows a slight n-type characteristic, and in this case, it can be adjusted to be substantially i-type by slightly including a p-type doping element. Note that, for the purpose of fine adjustment of the internal electric field strength distribution, n ⁻ Type or p ⁻ It may be a type. At this time, as a film structure, the surface shape after film formation is suitable for optical confinement as an aggregate of (110) -oriented columnar crystal grains generated as a result of preferential growth of the (110) plane among the crystal planes. It is desirable to have a self-generated uneven structure.
[0051]
As the n-type layer, a hydrogenated amorphous silicon film or a crystalline silicon film containing a microcrystalline silicon phase can be used. The thickness is adjusted in the range of about 2 to 100 nm depending on the material. 1 × 10 for doping element concentration ¹⁸ -10 ²¹ / Cm ³ The degree is substantially n ⁺ Type. The SiH used for film formation ₄ , H ₂ And the doping gas PH ₃ CH in addition to gases such as ₄ If an appropriate amount of gas containing C (carbon) such as _x C _1-x A film can be obtained, and a film with little light absorption loss can be formed, and it is also effective in reducing a dark current component for improving an open circuit voltage. A similar effect can be obtained by mixing an appropriate amount of a gas containing O (oxygen) or a gas containing N (nitrogen) in addition to C.
[0052]
In order to further improve the junction characteristics, a substantially i-type non-single-crystal Si layer may be inserted between the p-type layer and the photoactive layer or between the photoactive layer and the n-type layer. At this time, the thickness of the insertion layer is about 0.5 to 50 nm.
[0053]
Next, a metal film is formed as the back electrode 104. As the metal film material, it is desirable to use Al (aluminum), Ag (silver), or the like, which is excellent in conductive properties and light reflection properties. As the film forming method, known techniques such as an evaporation method, a sputtering method, an ion plating method, and a screen printing method can be used. At this time, the film thickness is about 0.1 μm or more. It is more preferable that the back electrode 104 has a structure in which a transparent conductive film and a metal film are stacked in this order from the surface side in contact with the semiconductor layer. By inserting the transparent conductive film between the semiconductor layer and the metal film in this manner, it is possible to suppress a phenomenon that the metal film component is diffused into the semiconductor layer and deteriorates device characteristics. In addition, if the surface on which the transparent conductive film is formed has an appropriate uneven structure, light can be effectively scattered, so that the light confinement effect that is effective for improving the efficiency of the solar cell can be enhanced. Here, the material of the transparent conductive film is SnO as described above. ₂ , ITO, ZnO, etc., and a known film forming method such as a CVD method, an evaporation method, an ion plating method, a sputtering method, a spray method, and a sol-gel method can be used.
[0054]
As described above, in the process of FIG. 1A, no film processing is performed between the formation of the front electrode 102 and the formation of the back electrode 104, and thus there is a possibility of generation of dust due to the processing, cleaning failure due to cleaning, and residue adhesion. It is possible to form an element without any defects, and to realize high element characteristics and high element yield.
[0055]
<Formation of first and second separation grooves (see FIG. 1B)>
After completing the element formation in FIG. 1A, a first separation groove and a second separation groove are formed, but it is not necessary to follow the order of the formation of the first separation groove and the formation of the second separation groove.
[0056]
The first separation groove is formed by a laser processing method so as to penetrate the back electrode 104, the semiconductor multilayer film 103, and the front electrode 102 and expose the light-transmitting substrate 101. At this time, for example, a fundamental wave of YAG (wavelength: 1.06 μm) is used as a laser, and the power is adjusted by the thickness of the deposited film. For example, when SnO2 is 500 nm as the front electrode 102, the above-mentioned Si-based film as the semiconductor multilayer film 103 is about 2 to 3 μm in thickness, and Ag is 0.2 μm as the back electrode 104, the laser power is about 2 to 4 W at the processing point. It may be adjusted within the range of. The processing width is about 50 to 100 μm. In addition, it is desirable that the laser irradiation direction is the glass surface side, and that the glass surface side is gravitationally upward so that abrasion dust generated during laser processing does not easily adhere to the device surface. It is desirable to be applied also in the processing step). As described above, a plurality of electrically isolated element regions are formed on the light-transmitting substrate.
[0057]
The second separation groove basically has the same process as that of the first separation groove. However, in order to stop the depth of the through hole in a state where the front electrode 102 is exposed, the laser wavelength used is the second harmonic ( 0.53 μm), and the power is adjusted in the range of about 0.1 to 0.5 W. By doing so, the semiconductor multilayer film 103 and the back electrode 104 can be removed preferentially and selectively while the front electrode 102 remains. As described above, each element region is divided and divided into a first region and a second region.
[0058]
Here, since the second separation groove can be formed in a condition range in which the semiconductor multilayer film is completely removed, it is not necessary to adjust laser processing conditions such as stopping in the middle of the semiconductor multilayer film as in the conventional example, and the yield is good. It can be a processing step.
[0059]
Further, the second isolation groove 106 completely removes the semiconductor multilayer film, so that the conductive material 110 formed in the connection groove / second connection port described later and the semiconductor multilayer film in the photovoltaic region are completely removed. Since there is a reverse junction or a conductive intermediate layer in the semiconductor multilayer film, as described in the section of the prior art, when the conductive layer is in contact with the conductive material of the connection groove, The problem of leaks can be completely avoided.
[0060]
In addition, although the etching method can be used for forming the first and second separation grooves, it is preferable to use a laser processing step which can realize a simple and low-cost processing operation.
[0061]
<Formation of insulating film and formation of first connection port (see FIG. 1C)>
After finishing up to FIG. 1B, formation of the insulating film 107 and formation of the first connection port 108 are performed.
[0062]
As the insulating film 107, in addition to a silicon oxide film of silicon oxide, a silicon nitride film of silicon nitride, and silicon carbide of silicon carbide, a titanium oxide film, a titanium nitride film, an aluminum oxide film, an aluminum nitride film, An oxide or nitride of a metal such as tantalum oxide, an inorganic insulating film such as a carbon film such as diamond or diamond-like carbon, or an organic insulating film such as a resin can be used. In particular, when a silicon oxide film or a silicon nitride film is used for the insulating film, an electrical passivation effect can be expected as well as a mere mechanical protection film. When a metal oxide or nitride is used for the insulating film, an insulating protective film having particularly excellent corrosion resistance can be formed. When diamond or diamond-like carbon is used for the insulating film, an insulating protective film having particularly excellent heat resistance can be formed. Here, as a method for manufacturing the inorganic insulating film, a sputtering method, a thermal CVD method, a PECVD method, a reactive evaporation method, a reactive ion plating method, or the like can be used. As a method for producing the organic insulating film, a printing method, a spray coating method, or the like can be used.
[0063]
The first connection port 108 may be formed by setting a mask having a predetermined pattern at a connection port formation position before forming the insulating film 107 and removing the mask after forming the insulating film 107. Alternatively, after the insulating film 107 is formed without the mask, it can be formed by additional processing. As the additional processing method, a mechanical scribe method, a wet or dry etching method or the like can be used in addition to the laser processing method. However, since the processing depth requires extremely high precision, it is preferable to use the former mask patterning method.
[0064]
One of the advantages of the present invention is that alignment of the mask does not require much accuracy. In other words, the first connection port 108 only needs to expose the back electrode 104 from the connection port 108. The allowable range of lateral displacement of the connection port 108 is the width of the back electrode 104 (about 5 to 20 mm). (The laser processing position is required to have a position accuracy of the order of 10 μm, whereas the mask alignment position only needs to have a position accuracy of the order of mm.)
[0065]
As described above, the cost of the process can be reduced.
[0066]
<Connection groove / Second connection port formation (see FIG. 1D)>
After completion of FIG. 1C, a connection groove / second connection port 109 is formed.
[0067]
When the insulating film 107 is an inorganic insulating film, the connecting groove / second connecting port 109 can be formed basically under substantially the same conditions as the formation conditions of the second separating groove 106. The laser power may be adjusted accordingly. If necessary, the insulating film may be preferentially grooved with a low-power fundamental wave, and then the remaining film may be removed with the second harmonic. Here, the connection groove / second connection port 109 can perform its function as long as the front electrode 102 is exposed. The connection groove / second connection port 109 does not necessarily need to be a continuous groove shape, and may be configured with a plurality of through holes. Good.
[0068]
<Formation of Series Connection and Third Separation Groove by Conductive Material (Refer to FIG. 1E)> After completion of FIG. 1D, formation of series connection by conductive material 110 and third separation groove 111 Is formed.
[0069]
As the conductive material 110, a metal film, a metal wire or a metal foil, a conductive resin, or the like can be used.
[0070]
When a metal film is used, it is desirable to use a material having a low resistivity, such as Ag, Al, or Cu (copper). Known techniques such as a sputtering method, an MOCVD method, an evaporation method, and an ion plating method can be used as the manufacturing method. Here, the third separation groove 111 can be formed by setting a mask at a predetermined position before forming the metal film and removing the mask after forming the metal film. Further, in order to increase the adhesive strength between the metal film and the front electrode 102 or the back electrode 104, an adhesion reinforcing layer can be inserted between the metal film and the front electrode 102 or the back electrode 104. As the adhesion reinforcing layer, for example, a metal material containing Ti, Cr, Ni, or the like, or a conductive oxide material such as SnO2, ITO, or ZnO can be used. A known technique such as an ion plating method can be used.
[0071]
Here, one of the advantages of the present invention is that the allowable range of the width size and positional accuracy of the mask is wide. That is, the width and the position of the third separation groove 111 for separating the metal film may be formed at any position between the connection groove / the second connection port and the first connection port. By appropriately devising the position of the connection port 108 in the back electrode 104, the width of the third separation groove 111 and the allowable range of positional deviation can be on the order of mm.
[0072]
When a metal wire or a metal foil is used, the back electrode 104 exposed at the first connection port and the front electrode 102 exposed at the second connection port are electrically connected to each other using a solder material or a conductive paste material as an intermediary. I do.
[0073]
In the case where a conductive resin is used, the third separation groove 111 can be formed at the same time by forming a predetermined pattern using a screen printing method.
[0074]
As described above, the cost of the process can be reduced.
[0075]
As described above, according to the present invention, in forming an integrated structure of a photoelectric conversion device, high characteristics, high yield, and low cost can be realized.
[0076]
<Generalization>
Here, the embodiment of the present invention has been described by taking a tandem thin-film Si solar cell as an example, but the present invention is not limited to this, and may be in any form without departing from the object of the invention.
[0077]
That is, the present invention is not limited to a tandem type having two semiconductor bonding layers and having one reverse junction or one intermediate conductive layer, but a multi-junction type having two or more reverse junctions or intermediate conductive layers. Also applicable to solar cells.
[0078]
Further, the present invention is not limited to a Si-based semiconductor, but can be applied to a case where a compound-based or organic-based semiconductor is used.
[0079]
【The invention's effect】
According to the present invention, since an element / process separation step is used in integration of a photoelectric conversion device, foreign substances generated in a processing step and deposits generated in a cleaning step are not mixed into a film, and a vertical Directional leakage is prevented.
[0080]
Further, since the connection groove and the semiconductor multilayer film of the photoelectric conversion portion are completely electrically separated from each other, even if a reverse junction or a conductive intermediate layer exists in the semiconductor multilayer film, a lateral direction caused by the reverse junction or the conductive intermediate layer exists. Leaks are prevented.
[0081]
In addition, since the precision required for the mask patterning process can be reduced, a cost reduction process can be realized.
[0082]
In particular, according to the third, fourth, and fifth aspects, it is possible to form a more reliable, simpler, and higher-yield ohmic contact, and to achieve higher efficiency by more efficiently distributing light energy.
[0083]
According to the silicon oxide or silicon nitride of claim 6, it is possible to form an extremely excellent insulating protective film that can also expect an electrical passivation effect.
[0084]
According to the seventh aspect, an insulating protective film having particularly excellent corrosion resistance can be formed.
[0085]
According to the eighth aspect, an insulating protective film having excellent heat resistance can be formed.
[0086]
According to the metal film or the conductive paste of the tenth aspect, series connection can be realized very simply and at low cost.
[0087]
According to the laser scribe method of the twelfth aspect, the processing operation can be performed very simply and at low cost.
[0088]
Further, according to the mask patterning method of the thirteenth aspect, it is possible to realize a simpler and lower cost process.
[0089]
Further, the use of the mask patterning method in claim 14 enables a simpler and lower cost process.
[0090]
Furthermore, according to the metal film or the conductive paste according to the fifteenth aspect, series connection can be realized very simply and at low cost.
[0091]
As described above, in the integrated structure of the photoelectric conversion device, high characteristics, high yield, and low cost can be realized.
[Brief description of the drawings]
FIGS. 1A to 1E are cross-sectional views illustrating an integrated structure of a photoelectric conversion device according to the present invention and a manufacturing process thereof. It is sectional drawing which shows one Embodiment of a solar cell typically.
FIGS. 2A to 2C are cross-sectional views illustrating an integrated structure of a conventional photoelectric conversion device and a manufacturing process thereof.
3A to 3D are cross-sectional views illustrating an integrated structure of a conventional photoelectric conversion device and a manufacturing process thereof.
FIG. 4 is a cross-sectional view illustrating an example in which a conventional integrated structure is applied to a conventional tandem element.
FIG. 5 is a cross-sectional view illustrating another example in which a conventional integrated structure is applied to a conventional tandem element.
[Explanation of symbols]
101: translucent substrate
102: Front electrode
103: semiconductor multilayer film
103a: first semiconductor bonding layer
103b: second semiconductor bonding layer
104: Back electrode
105: first separation groove
106: second separation groove
107: insulating film
108: first connection port
109: connection groove / second connection port
110: conductive material
111: Third separation groove

Claims (15)

A plurality of semiconductor elements in which a front electrode, a semiconductor multilayer film having at least one semiconductor junction, and a back electrode are formed in this order on a light-transmitting substrate are connected in series between adjacent semiconductor elements by a conductive material. In the photoelectric conversion device having the integrated structure, the plurality of semiconductor elements are separated from each other by a first separation groove separating the back electrode from the front electrode, and each of the plurality of semiconductor elements is A first region and a second region are separated by a second separation groove separating the electrode from the semiconductor multilayer film, and the series connection between adjacent ones of the plurality of semiconductor devices is performed by the one of the semiconductor devices. This is realized by connecting a back electrode in the first region and a front electrode in the second region of the other semiconductor element adjacent to the one semiconductor element with a conductive material. The photoelectric conversion device, characterized in that. The semiconductor element is covered with an insulating film, and the connection between the back electrode of the one semiconductor element and the front electrode of the other semiconductor element by the conductive material is performed in the first region of the one semiconductor element. A first connection port formed in the insulating film, and a second region of the other semiconductor element adjacent to the one semiconductor element, wherein the insulating film, the back electrode, and the semiconductor multilayer film are provided. Through a second connection port formed by a connection groove that reaches the front electrode, and the first separation groove and the second separation groove are covered with the insulating film. The photoelectric conversion device according to claim 1, wherein: The photoelectric conversion device according to claim 1, wherein there are a plurality of semiconductor bonding layers in the semiconductor film, and a metal layer or a transparent conductive layer is interposed between at least one semiconductor bonding layer. The photoelectric conversion device according to claim 3, wherein the metal layer is made of an alloy material containing silicon. The photoelectric conversion device according to claim 3, wherein the transparent conductive layer is made of a metal oxide containing at least one of indium oxide, indium-tin oxide, tin oxide, and zinc oxide. apparatus. The photoelectric conversion device according to claim 2, wherein the insulating film is made of a material containing at least one of silicon oxide, silicon carbide, and silicon nitride. The photoelectric conversion device according to claim 2, wherein the insulating film is made of a material containing at least one of a metal oxide and a metal nitride. The photoelectric conversion device according to claim 2, wherein the insulating film is made of a material containing at least one of diamond and diamond-like carbon. The photoelectric conversion device according to claim 2, wherein the insulating film is made of a resin material. The photoelectric conversion device according to claim 1, wherein the conductive material is at least one of a metal film, a metal wire, a metal foil, and a conductive paste. A first step of sequentially laminating a front electrode, a semiconductor multilayer film having at least one or more semiconductor junctions, and a back electrode on a translucent substrate to form a first laminate, and a first separation A second step of separating the first stacked body into a plurality of elements by a groove, and a semiconductor multilayer film of a front electrode, a semiconductor multilayer film, and a back electrode constituting each of the plurality of elements by a second separation groove A third step of separating at least two regions, a connection region and a power generation region, of the laminated body portion including the first electrode and the back electrode, and at least the back electrode, the first separation groove, and the second separation groove exist. A fourth step of laminating and forming an insulating film so as to cover the region, a fifth step of forming a first connection port penetrating the insulating film and reaching the back electrode in the power generation region, and A second connecting groove reaching the front electrode A sixth step of forming a connection port, a back electrode located at the first connection port in one of the separated devices, and a second electrode adjacent to the one device separated by the first separation groove. The plurality of elements are connected in series by electrically connecting the front electrode located at the second connection port of the element with a conductive material and sequentially repeating this connection structure for further adjacent elements. A method for manufacturing a photoelectric conversion device, comprising a seventh step of causing 12. The method according to claim 11, wherein at least one of the first separation groove and the second separation is formed by a laser scribe method or an etching method. 12. The method according to claim 11, wherein the first connection port is formed by a mask patterning method or a laser scribe method. The method according to claim 11, wherein the seventh step is performed by combining a metal film forming method and a mask patterning method or an etching method. The method according to claim 11, wherein at least one of a metal film, a metal wire, a metal foil, and a conductive paste is used as the conductive material in the seventh step.

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