JP2017228661A - Method for manufacturing hbc type crystal-based solar cell and hbc type crystal-based solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an HBC (hetero type back-contact) crystal-based solar cell, by which the manufacturing process can be simplified and an electrode having a sharp contour in a plan view can be stably obtained.SOLUTION: The method includes, successively in the following order: a step of using a substrate made of a crystalline silicon having a first conductivity type and forming i-type amorphous Si layers α, β respectively covering one surface and the other surface of the substrate; a step of forming a photoresist in a region of an outer surface of the β layer, the region where impurities are not introduced in a subsequent step; a step of forming a portion A having the same conductivity type as the first conductivity type and a portion B having a conductivity type different from the first conductivity type, at the positions spaced from each other by the photoresist, by an ion implantation process using the mask in such a manner that the portions are included in the β layer while the portions are partially exposed on the outer surface of the β layer; a step of subjecting the substrate to annealing; a step of forming a conductive member to cover the portions A, B and the photoresist; and a step of removing the photoresist covered with the conductive member.SELECTED DRAWING: Figure 5

Description

  INDUSTRIAL APPLICABILITY The present invention provides a method for manufacturing an HBC type crystalline solar cell and an HBC type crystalline solar cell in which the manufacturing process can be simplified and an ion implantation region and electrode shape having a sharp outline in a plan view can be stably obtained. It relates to batteries.

  Conventionally, it is known that a solar cell using a crystalline silicon substrate (hereinafter also referred to as a crystalline solar cell) can obtain high power generation efficiency in a back contact solar cell. Among them, hetero-type back contact type (HBC type) crystalline solar cells have been attracting attention from various fields because the world's highest power generation efficiency has been confirmed.

  Such an HBC type crystalline solar cell has an n-type amorphous Si layer and a p-type amorphous layer on the back surface of the silicon substrate (the surface located on the opposite side of the light incident surface) via an i-type amorphous Si layer. The portions made of the Si layer are arranged locally and are separated from each other. In order to achieve such a configuration, it is known that an HBC type crystal solar cell is manufactured through a process as shown in FIG. 25 (for example, the prior art of Patent Document 1).

FIG. 25 is a schematic cross-sectional view showing an example of a manufacturing method according to a conventional HBC crystal solar cell. That is,
FIG. 25A shows the formation of an i-type amorphous Si layer 1002 and an n-type amorphous Si layer 1003 on one surface of silicon 1001.
FIG. 25B shows the formation of a photoresist 1004 having a desired pattern on the n-type amorphous Si layer 1003.
In FIG. 25C, the i-type amorphous Si layer 1002 and the n-type amorphous Si layer 1003 are etched using a photoresist 1004.
In FIG. 25D, the photoresist 1004 is removed after etching.
FIG. 25E shows the formation of the etch stopper layer 1005. The etch stopper layer 1005 is masked, and the etch stopper layer 1005 in the separated portion where the n-type amorphous Si layer is not formed is etched. Furthermore, an i-type amorphous Si layer 1006 and a p-type amorphous Si layer 1007 are formed over the entire region.

In FIG. 25 (f), a photoresist 1008 is formed in the separated portion.
In FIG. 25G, the i-type amorphous Si layer 1006 and the p-type amorphous Si layer 1007 are etched using a photoresist 1008.
In FIG. 25H, the photoresist 1008 is removed after etching.
In FIG. 25I, the etch stopper layer 1005 is peeled off.
In FIG. 25 (j), an i-type amorphous Si layer 1009 is formed in a separation portion between i-type amorphous Si layers 1002 and a separation portion between n-type amorphous Si layer 1003 and p-type amorphous Si layer 1007.

  In other words, in the conventional method for manufacturing an HBC type crystalline solar cell, a specific pattern region consisting of the n-type amorphous Si layer 1003 and the p-type amorphous Si layer 1007 is not obtained until the above-mentioned numerous steps [FIG. 25]. For this purpose, a technique such as photolithography or etching must be performed many times. However, when patterning is performed by such a method, the number of processes increases as shown in FIG. 25, leading to an increase in the cost of the production line, and it is difficult to reduce the cost of the solar cell.

JP 2012-243797 A

  The present invention has been made in view of the above circumstances, and can greatly reduce the number of steps in manufacturing, and can stabilize an ion implantation region and electrode shape having a sharp outline in plan view. It is an object of the present invention to provide a method for producing an HBC crystal solar cell and an HBC crystal solar cell obtained by the above method.

  The method for manufacturing an HBC type crystalline solar cell according to claim 1 of the present invention uses a substrate made of crystalline silicon of the first conductivity type, and an i-type amorphous covering one surface on which light is incident on the substrate. In the step of forming the Si layer α and the i-type amorphous Si layer β covering the other side opposite to the one surface individually or simultaneously, and in the subsequent step, of the outer surface of the amorphous Si layer β A step of forming a photoresist so as to cover a region where impurities are not introduced, and a mask so as to be exposed in the amorphous Si layer β and partially exposed to the outer surface side of the amorphous Si layer β. By using the ion implantation method, the portion A having the same conductivity type as the first conductivity type and the portion B having a conductivity type different from the first conductivity type are formed by the photoresist (the photoresist exists). The step of forming at positions separated from each other, the step of annealing the amorphous Si layer β after the ion implantation, and the portion A, which is located on the outer surface side of the amorphous Si layer β, A step of forming a conductive member so as to cover the part B and the photoresist, and a step of removing the photoresist covered with the conductive member are provided in order.

  The method of manufacturing an HBC type crystalline solar cell according to claim 2 of the present invention is the method of manufacturing the HBC type crystalline solar cell according to claim 1, when the part A or part B into which ions are implanted through the opening of the mask is viewed in plan view. A mask having a shape of an opening so that a portion of the photoresist defining the outer shape of the portion B can be seen is used.

  According to a third aspect of the present invention, there is provided a method for manufacturing an HBC type crystalline solar cell, wherein the first step is to cover the i-type amorphous Si layer α before the step of forming the photoresist. A step of forming an n-type amorphous Si layer, and a step of forming a SiN layer so as to cover the n-type amorphous Si layer.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing an HBC type crystalline solar cell according to the first or second aspect, wherein the i-type amorphous Si layer α is covered before the step of forming the photoresist. The step of forming the n-type amorphous Si layer includes the step of forming the SiN layer so as to cover the n-type amorphous Si layer after the step of forming the conductive member. Features.

  The method for producing an HBC type crystalline solar cell according to claim 5 of the present invention covers the i-type amorphous Si layer α after the step of forming the conductive member in claim 1 or 2. And a step of forming a SiN layer.

  The HBC type crystalline solar cell according to claim 6 of the present invention covers a substrate made of crystalline silicon of the first conductivity type that exhibits a photoelectric conversion function, and a surface on which light is incident on the substrate. At least an i-type amorphous Si layer α disposed and an i-type amorphous Si layer β disposed so as to cover the other surface opposite to the one surface of the substrate, the amorphous Si layer β A portion A having the same conductivity type as the first conductivity type and a portion B having a conductivity type different from the first conductivity type so that a part is exposed on the outer surface side of the amorphous Si layer β. The electrodes are made of conductive members so as to be separately disposed from each other and to individually cover the exposed outer surfaces of the part A and the part B, respectively.

  The method for manufacturing an HBC type crystalline solar cell according to the present invention uses a substrate made of crystalline silicon of the first conductivity type, and forms i-type amorphous Si layers α and β covering one surface and the other surface of the substrate, respectively. And a step of forming a photoresist in a region of the outer surface of β that does not introduce impurities in a subsequent step, and a part of the outer surface of β that is inherent in β and exposed to the outer surface of β As described above, a portion A having the same conductivity type as the first conductivity type and a portion B having a conductivity type different from the first conductivity type are formed at positions separated by the photoresist by an ion implantation method using a mask. A step of performing an annealing process, a step of forming a conductive member so as to cover the portion A, the portion B, and the photoresist, and a step of removing the photoresist covered with the conductive member And in order This makes it possible to produce an HBC type crystalline solar cell having the above-described configuration.

Therefore, according to the manufacturing method of the present invention, it is possible to significantly reduce the number of steps in manufacturing compared to the conventional manufacturing method. In addition, when forming part A or part B by ion implantation using a mask, the presence of a photoresist between part A and part B stabilizes the ion implantation region having a sharp outline in plan view. Is obtained. Furthermore, only by removing the photoresist, the conductive member in the region covering the photoresist (the region overlapping on the photoresist) is also removed together with the photoresist. Therefore, according to the present invention, electrodes that individually cover the portions A and B can be naturally obtained without patterning the conductive member.
Therefore, the present invention can greatly reduce the number of steps in manufacturing, and can stably obtain an ion implantation region having a sharp outline in a plan view and an electrode that does not require a patterning process. A method for producing an HBC type crystalline solar cell is provided. Therefore, the present invention contributes to the construction of a low-cost production line for HBC type crystalline solar cells.

The HBC type crystalline solar cell according to the present invention includes i-type amorphous Si layers α and β that respectively cover one side and the other side of a substrate made of crystalline silicon of the first conductivity type. Here, the i-type amorphous Si layer α is disposed on the front surface (light incident surface) of the substrate, and the i-type amorphous Si layer β is disposed on the back surface of the substrate (the other surface that is located on the opposite side of the light incident surface). Has been. Further, a part A having the same conductivity type as the first conductivity type and a part B having a conductivity type different from the first conductivity type are included in the β and partly exposed on the outer surface side of the β. Are spaced apart from each other. This configuration can be formed only by performing an ion implantation process for forming the part A and the part B on the amorphous Si layer β. Therefore, this configuration maintains a flat profile on the outer surface of the amorphous Si layer β even after the formation of the portion A and the portion B, so that the electrode made of a conductive member formed in the subsequent process also has flatness. Kept. Therefore, it is possible to stabilize the removal of the photoresist that is performed in order to leave the electrodes so as to overlap the portions A and B, respectively.
Therefore, the present invention contributes to the provision of an HBC crystal solar cell that can greatly reduce the number of steps in the production line.

1 is a schematic cross-sectional view showing a first embodiment of an HBC type crystalline solar cell according to the present invention. The schematic cross section which shows the manufacturing process of the HBC type crystalline solar cell of FIG. FIG. 3 is a schematic cross-sectional view showing a next step of FIG. 2. FIG. 4 is a schematic cross-sectional view showing the next step of FIG. 3. FIG. 5 is a schematic cross-sectional view showing the next step of FIG. 4. The flowchart which shows the manufacturing process of the HBC type | mold crystalline solar cell of a prior art example (FIG. 25). The flowchart which shows the manufacturing process of the HBC type | mold crystalline solar cell of this invention (FIG. 1). The graph which shows the relationship between the ion energy of boron (B), and a stopping range. The graph which shows the profile of the phosphorus (P) density | concentration observed in the depth direction of a board | substrate, changing the ion energy of phosphorus (P). The schematic cross section of the film-forming apparatus used for formation of an amorphous Si film or the like. The schematic cross section of an ion implantation apparatus. The schematic cross section of an annealing treatment apparatus. The schematic cross section which shows 2nd embodiment of the HBC type | system | group crystalline solar cell which concerns on this invention. FIG. 14 is a schematic cross-sectional view showing a manufacturing process of the HBC type crystalline solar cell in FIG. 13. FIG. 15 is a schematic cross-sectional view showing the next step of FIG. 14. FIG. 16 is a schematic cross-sectional view showing the next step of FIG. 15. FIG. 17 is a schematic cross-sectional view showing the next step of FIG. 16. The flowchart which shows the manufacturing process of the HBC type | mold crystalline solar cell of this invention (FIG. 13). The schematic cross section which shows 3rd embodiment of the HBC type crystalline solar cell which concerns on this invention. FIG. 20 is a schematic cross-sectional view showing a manufacturing process of the HBC type crystalline solar cell in FIG. 19. FIG. 21 is a schematic cross-sectional view showing the next step of FIG. 20. FIG. 22 is a schematic cross-sectional view showing the next step of FIG. 21. FIG. 23 is a schematic cross-sectional view showing the next step of FIG. 22. The flowchart which shows the manufacturing process of the HBC type | mold crystalline solar cell of this invention (FIG. 19). The schematic cross section which shows the manufacturing process of the conventional HBC type | mold crystalline solar cell.

Hereinafter, an embodiment of a hetero-type back contact type (HBC type) crystalline solar cell according to the present invention will be described with reference to the drawings.
<First embodiment> --- Generic concept & Process A
(HBC type crystalline solar cell)
FIG. 1 is a diagram for explaining the configuration of an HBC crystal solar cell 100I (100) according to the first embodiment of the present invention.
The solar cell 100I (100) of the first embodiment is formed so that “n ⁺ site and p ⁺ site” described later cover the back surface of the substrate (opposite side of the light incident surface: the lower surface in FIG. 1). In this case, it is formed near the back surface inside the i-type amorphous Si layer by an ion implantation method.
In this embodiment, an ion implantation method is used to form the n ⁺ site and the p ⁺ site. However, as long as impurity atoms are introduced into the amorphous Si layer in an ion state, the technique is applied to the ion implantation method. However, the impurity introduction may be performed using a plasma doping method or the like. However, in the following description, an ion implantation method will be described in detail as a representative example of the impurity introduction method.

The HBC type crystalline solar cell 100I according to the first embodiment includes a substrate 101 made of crystalline silicon of a first conductivity type (for example, an n-type semiconductor) that exhibits a photoelectric conversion function, and light (arrow) with respect to the substrate 101. I-type amorphous Si layer (α) 112 disposed so as to cover one surface 101a on which the light is incident, and i-type disposed so as to cover the other surface 101b located on the opposite side of the one surface 101a. And an amorphous Si layer (β) 102.
In the HBC type crystalline solar cell 100I, an n-type amorphous Si layer 113 and an antireflection layer (AR layer) are provided on one surface 101a side of the substrate 101 so as to cover the i-type amorphous Si layer (α). 114) are arranged in order. As the antireflection layer 114, for example, an insulating nitride film, silicon nitride film, titanium oxide film, aluminum oxide film or the like is preferably used.

In addition, the HBC type crystalline solar cell 100I is the same as the first conductivity type so that it is embedded in the amorphous Si layer β102 and partly exposed on the outer surface side of the amorphous Si layer (β) 102. A conductive type (for example, n ⁺ -type) portion (A) 103 and a conductive type portion (B) 104 different from the first conductive type are arranged apart from each other. In FIG. 1, a part (C) represents a separation part between the part (A) 103 and the part (B) 104.

That is, in the HBC type crystalline solar cell 100D according to the first embodiment, the region (A) 103 and the region (B) 104 are each formed by injecting a desired element into the surface layer portion of the substrate 101. This is the case.
In FIG. 1, the symbol d1 represents the thickness of the amorphous Si layer (β) 102, and the symbol d2 represents the depths of the part (A) 103 and the part (B) 104. An example of the thickness d1 of the amorphous Si layer (β) 102 is about 200 nm. Part (A) 103 and part (B) 104 are formed by an ion implantation method to be described later.

  According to this method, the amorphous Si layer (β) 102 can be formed only by performing an ion implantation process for producing the part (A) 103 and the part (B) 104, respectively. Therefore, this configuration maintains a flat profile on the outer surface of the amorphous Si layer (β) 102 even after the formation of the portion (A) 103 and the portion (B) 104. Therefore, the flatness of the electrode BM made of a conductive member, which is formed on the part (A) 103 and the part (B) 104 in the subsequent process, is also maintained. In addition, it is possible to stabilize the removal of the photoresist that is performed in order to leave the electrode BM in a portion that overlaps the portion A and the portion B, respectively.

(Method for producing HBC type crystalline solar cell)
A method of manufacturing the HBC crystal solar cell 100I (100) according to the first embodiment shown in FIG. 1 will be described. 2 to 5 are schematic cross-sectional views showing a procedure for manufacturing the HBC type crystalline solar cell of FIG. FIG. 7 is a flowchart showing manufacturing steps of the HBC type crystalline solar cell shown in FIG. Hereinafter, “amorphous Si” is abbreviated as “a-Si”.
Hereinafter, differences between the conventional example and the first embodiment will be described with reference to FIGS. 6 and 25 showing the conventional example as appropriate.

  Each process for manufacturing the HBC type crystalline solar cell 100 according to the first embodiment will be described in detail. First, in the texture formation step, wet etching processing using, for example, potassium hydroxide (KOH) or sodium hydroxide (NaOH) as an etchant is performed on the substrate 101. Then, organic substances and metal contaminants remaining on the processed substrate 101 are removed using hydrofluoric acid. Thus, the one surface 101a and the other surface 101b of the substrate 101 are processed into a textured shape [first step: FIG. 2 (a)].

An i-type a-Si film (α) 112 and an i-type a-Si film (β) 102 are formed on the one surface 101a and the other surface 101b of the substrate 101 processed into a shape having the above texture, respectively, under predetermined conditions. Then, a film is formed by a CVD method [second step: FIG. 2 (b)].
Next, an n-type a-Si film 113 and a silicon nitride (SiN) film 114 are sequentially formed on the i-type a-Si film 112 disposed on the one surface 101a of the substrate 101 by a CVD method under predetermined conditions. A film is formed [third step: FIG. 2 (c)].

The film formation in the second step and the third step is performed using, for example, a manufacturing apparatus (hereinafter also referred to as a CVD apparatus) 700 that forms a film using the CVD method shown in FIG.
In the CVD apparatus 700 of FIG. 10, the process chambers are arranged in series, and a tray (not shown) on which a substrate 101 made of crystalline silicon is mounted passes through each process chamber in order. A type a-Si film 112, an i-type a-Si film 102, an n-type a-Si film 113, and a silicon nitride (SiN) film 114 are formed on the substrate 101.

The CVD apparatus 700 includes a preparation chamber (L) 751, a heating chamber (H) 752, a film formation inlet chamber (EN) 753, a first film formation chamber (S1) 754, a second film formation chamber (S2) 755, and a third. A film formation chamber (S3) 756, a fourth film formation chamber (S4) 757, a film formation outlet chamber (EX) 758, a transfer chamber (T) 759, and an extraction chamber (UL) 760 are provided.
The substrate 101 mounted on the tray (not shown) carried in from the charging chamber (L) 751 has textures formed in advance on both the front and back surfaces, and is loaded in the charging chamber (not shown). L) It can move only in the forward direction from 751 to the take-out chamber (UL) 760. That is, in the manufacturing apparatus 700 of FIG. 10, the substrate 101 mounted on the tray (not shown) does not need to return in the reverse direction [from the take-out chamber (UL) 760 to the preparation chamber (L) 751]. Therefore, the manufacturing apparatus 700 of FIG. 10 is excellent in mass productivity.

  The substrate 101 carried into the preparation chamber 751 is moved to the heating chamber 752 from the preparation chamber 751 after being in a desired reduced pressure atmosphere, and is heated by the heater 752H at the point A. The substrate 101 that has reached a desired temperature is moved to the film formation inlet chamber 753, and the atmosphere of the film formation inlet chamber 753 in which the substrate 101 is accommodated is the i-type a-Si film 112 in the next first film formation chamber 754. It adjusts according to the atmospheric conditions at the time of formation. The film formation inlet chamber 753 includes a heater 753H, and the temperature of the substrate 101 is adjusted so as to be a temperature preferable for the production of the i-type a-Si film α (112).

  Next, the temperature-adjusted substrate 101 is moved to the first film formation chamber 754 and passes through the point C, so that the i-type a-Si film α (112) is formed only on one surface side of the substrate 101 by the CVD method. Is formed. Thereby, a state in which the a-Si film α (112) is formed on one surface (101a) of the base 101 is obtained. Here, the cathode 754C2 is connected to a power source 754E2, and a desired film-forming gas is introduced from the gas supply means 754G during film formation.

  Next, the substrate 101 on which the i-type a-Si film α (112) is formed is moved to the second film formation chamber 755 and passes through the point D, so that only the other surface side of the substrate 101 is formed by the CVD method. The i-type a-Si film (β) 102 is formed. As a result, a state in which the i-type a-Si film (β) 102 is formed on the other surface (101b) of the base 101 is obtained. This state is the HBC type crystalline solar cell 100B having the configuration shown in FIG. Here, the cathode 755C1 is connected to the power source 755E1, and a desired film-forming gas is introduced from the gas supply means 755G during film formation.

  Next, the substrate 101 on which the i-type a-Si film α (112) and the i-type a-Si film (β) 102 are formed is moved to the third film formation chamber 756 and passes through the point E, so that CVD is performed. By the method, the n-type a-Si film 113 is formed only on the i-type a-Si film α (112) on the one surface side of the substrate 101. Thereby, a state in which the n-type a-Si film 113 is formed on the i-type a-Si film α (112) on the one surface (101a) side of the base 101 is obtained. Here, the cathode 756C2 is connected to a power source 756E2, and a desired film forming gas is introduced from the gas supply means 756G during film formation.

  Next, the substrate 101 on which the i-type a-Si film α (112) and the n-type a-Si film 113 are formed on one surface side is moved to the fourth film formation chamber 757 and passes through the point F, so that the CVD is performed. By the method, a silicon nitride (SiN) film 114 is formed only on the n-type a-Si film 113 on the one surface side of the substrate 101. As a result, a state in which the n-type a-Si film 113 and the SiN film 114 are sequentially stacked on the i-type a-Si film α (112) on the one surface (101a) side of the substrate 101 is obtained. This state is the HBC type crystalline solar cell 100C having the configuration shown in FIG. Here, the cathode 757C2 is connected to a power source 757E2, and a desired film forming gas is introduced from the gas supply means 757G during film formation.

  In the first film formation chamber 754 to the fourth film formation chamber 757, the i-type a-Si film (α) 122, the i-type a-Si film (β) 102, the n-type a-Si film 113, and the SiN film 114 are formed. In this case, the temperature of the substrate may be controlled to be a temperature preferable for manufacturing each thin film by using temperature control means 754TC1, 755TC2, 756TC1, and 757TC1 provided in each film formation chamber.

  As shown in FIG. 2C, the i-type a-Si film (α) 122, the n-type a-Si film 113 and the SiN film 114 are formed on one side, and the i-type a-Si film (β) is formed on the other side. The substrate 101 on which each of the substrates 102 is formed is moved to the film formation outlet chamber (EX) 758, then transferred to the take-out chamber (UL) 760 via the transfer chamber (T) 759, and the inside of the take-out chamber is enlarged. By setting it to atmospheric pressure, it is carried out of the sputtering apparatus.

  Thereafter, a desired photoresist PR is applied to the i-type a-Si film 102 disposed on the other surface 101b of the substrate 101, and then patterned. As a result, in the subsequent step, a photoresist PR having a predetermined opening in the ion implantation region is formed on the i-type a-Si film 102 [fourth step: FIG. 2D]. Although a known material can be used as the photoresist material, the organic-inorganic hybrid photoresist material such as SOG (Spin-On-Glass) material is more preferable than the completely organic photoresist material such as PMMA. Is preferable because of its high resistance to ion implantation. Further, after forming a photoresist with a known photoresist material, a very thin metal film of several nm (for example, 1 to 5 nm) may be formed to have a function as a photoresist.

Next, p-type ions such as boron (B) ions are locally implanted into the vicinity of the outer surface 102b of the i-type a-Si film 102 through the mask M1 [fifth step: FIG. 3A]. To form a p ⁺ site (A) 103 [fifth step: FIG. 3 (c)].
At that time, as shown in FIG. 3B, when the portion A into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion A is visible. A mask having the shape of the opening is used.

In FIG. 3B, when M1e is defined as the position when the end of the mask M1 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the masks M1 It is designed so that the difference (Δm1A, Δm1B) between M1e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M1, the outer shape of the portion A can be more sharply defined than when only the mask M1 is used. Therefore, according to the present invention, the p ⁺ site (A) 103 can be formed in a clear shape up to the outer edge.

Then, in the outer surface 102b near the i-type a-Si film 102, between and if ^{p +} region (A) 103, and a position which does not overlap with the ^{p +} region (A) 103, phosphorus (P) ions or the like N-type ions are locally implanted through the mask M2 [sixth step: FIG. 4 (a)], thereby forming an n ⁺ region (B) 104 [sixth step: FIG. 4 (c). ].
At this time, as shown in FIG. 4B, when the portion B into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion B is visible. A mask having the shape of the opening is used.

In FIG. 4B, when M2e is defined as the position when the end of the mask M2 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the masks M2 It is designed so that the difference (Δm1A, Δm1B) between M2e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M2, the outer shape of the portion B can be defined more sharply than when only the mask M2 is used. Therefore, according to the present invention, the n ⁺ portion (B) 104 can be formed in a clear shape up to the outer edge.

As a result, the same conductivity type as the first conductivity type of the substrate (for example, n ⁺ -type) is present in the i-type a-Si layer 102 and partly exposed to the outer surface side of the a-Si layer 102. ) Part (A) 103 and part (B) 104 of a conductivity type different from the first conductivity type are formed to form an HBC crystal solar cell 100G [FIG. 4 (c). ]. At this stage, in the i-type a-Si layer 102, the photoresist PR exists on the part (C) that forms the separation part of the part (A) and the part (B).

Next, after the annealing process [seventh step], a conductive member BM functioning as an electrode is formed so as to cover the part A, the part B, and the photoresist. The annealing process will be described in detail later.
The conductive member BM is formed by sputtering under predetermined conditions [eighth step: FIG. 5A]. Thereby, the conductive member BM formed on the part A and the part B and the conductive member BM formed on the photoresist are disconnected.
As the conductive member BM, a material having high conductivity (low resistance) is suitable for use as an electrode, and examples thereof include Ag, Al, Cu, and Ti. The conductive member BM may be a laminated film of two or more layers in addition to a single layer film. A typical example is a laminated film of a transparent conductive film (ITO or the like) and a metal film (Ag or the like).

Finally, the photoresist is removed from the outer surface of the a-Si layer 102 by, for example, irradiating UV light [ninth step: FIG. 5B]. At that time, the conductive member BM on the photoresist is also removed together. As a result, the conductive member BM remains on the outer surface of the a-Si layer 102 only in the part formed on the part A and the part B. Therefore, the conductive member BM along the part A or the part B is formed and can be used as an electrode. This process is a so-called “lift-off” process.
The HBC crystal solar cell 100I (100) having the configuration shown in FIG. 1 can be manufactured by simply providing the above steps in order.

Here, as shown in FIG. 2B, the i-type a-Si film (β) 102 is originally formed as a single film in the thickness direction and the in-plane direction. For this reason, even when the p ⁺ site (A) 103 and the n ⁺ site (B) 104 are formed in the vicinity of the outer surface 102b of the i-type a-Si film 102 in the subsequent third and fourth steps, they are separated portions. The portion (C), that is, the region where ions are not implanted exists as a single film in the thickness direction.

Furthermore, by forming the p ⁺ portion (A) 103 and the n ⁺ portion (B) 104 so as not to reach the other surface 101b of the substrate, the i-type a-Si film 102 that is a single film is formed. The i-type a-Si film 102 existing on and in contact with the other surface 101b of the substrate exists as a single film continuous over the in-plane direction of the substrate.
Thus, in the HBC type crystalline solar cell 100I (100) of the present embodiment (FIG. 1), the i-type a-Si layer 102 is other than the p ⁺ site (A) 103 and the n ⁺ site (B) 104. By presenting as a “single film” in the region (where “single film” means that no interface exists inside the i-type a-Si layer 102), i-type a- The function of the Si film 102 as a passivation film is maintained.

  On the other hand, in the conventional configuration shown in FIG. 25 (j), an n-type a-Si layer 1003 and a p-type a-Si layer 1007 are formed between these layers and the substrate 1001. In the i-type a-Si layer 1002 to be formed, a separation portion is once formed in the surface direction of the substrate by etching (the states of FIGS. 25C and 25G), and finally shown in FIG. As described above, the i-type a-Si layer 1009 is formed in the separation portion, and the separation portion is embedded. Therefore, in the i-type a-Si layer in FIG. 25 (j), an interface exists in the in-plane direction of the substrate (corresponding to the dotted line between 1002 and 1009 in FIG. 25 (j)). Due to the presence of such an interface, the film becomes discontinuous in the in-plane direction of the substrate, and the i-type a-Si layer may not function effectively as a passivation film.

FIG. 8 is a graph showing the relationship between the ion energy (Ion Energy) of boron (B) and the stopping range (Stopping Range).
The stopping range is an index representing how far the implanted ions can enter the film in the depth direction of the film.
From this graph, it was found that the ion energy and the stopping range have a proportional relationship that the ion implantation depth increases as the ion energy increases. Therefore, by selecting a predetermined ion energy, when boron (B) is ion-implanted into the i-type a-Si layer 102, it is possible to change the position where the ion is retained at a specific depth. By utilizing this relationship, the p ⁺ site (A) 103 in FIG. 1 can be formed with good reproducibility.

As an example, by selecting 3 keV as the ion energy, the p ⁺ site (A) 103 having a depth of about 15 nm can be obtained. In this case, if the thickness d1 of the i-type a-Si layer 102 shown in FIG. 1 is 200 nm, the thickness remaining without being implanted with boron (B) ions is the value indicated by (d1-d2) in FIG. Thus, the portion of the i-type a-Si layer 102 having the thickness of d1-d2 exists as a single film over the in-plane direction of the substrate.

As ion energy at the time of ion implantation, as in the above example, the thickness d1 of the i-type a-Si layer 102 that forms the p ⁺ site (A) 103 and the n ⁺ site (B) 104, and the passivation film The thickness (d1−d2) of the portion of the i-type a-Si layer 102 that is necessary for the p ⁺ portion (A) 103 and the thickness d2 that is necessary for the n ⁺ portion (B) 104 is set to an appropriate value. As will be selected, there is a problem that when the ion energy increases, the surface of the i-type a-Si layer 102 to be processed becomes rough and flatness cannot be maintained. For this reason, when processing is performed on the i-type a-Si layer 102, the ion energy [keV] is preferably 20 or less, and the thickness of the i-type a-Si layer 102 (that is, i In view of the relationship between the thickness of the mold a-Si layer and the thickness desired to remain as the passivation film, it can be said that 5 or less is preferable. If the ion energy [keV] is 5 or less, the process is performed with lower energy, and the flatness of the surface of the i-type a-Si layer 102 can be maintained.

As an example, by selecting 3 keV as the ion energy, the p ⁺ site (A) 103 having a depth of about 15 nm can be obtained. In this case, if the thickness d1 of the i-type a-Si layer 102 shown in FIG. 1 is 200 nm, the thickness remaining without being implanted with boron (B) ions is the value indicated by (d1-d2) in FIG. Thus, the portion of the i-type a-Si layer 102 having the thickness of d1-d2 exists as a single film over the in-plane direction of the substrate.

As ion energy at the time of ion implantation, as in the above example, the thickness d1 of the i-type a-Si layer 102 that forms the p ⁺ site (A) 103 and the n ⁺ site (B) 104, and the passivation film The thickness (d1−d2) of the portion of the i-type a-Si layer 102 that is necessary for the p ⁺ portion (A) 103 and the thickness d2 that is necessary for the n ⁺ portion (B) 104 is set to an appropriate value. As will be selected, there is a problem that when the ion energy increases, the surface of the i-type a-Si layer 102 to be processed becomes rough and flatness cannot be maintained. For this reason, when processing is performed on the i-type a-Si layer 102, the ion energy [keV] is preferably 20 or less, and the thickness of the i-type a-Si layer 102 (that is, i In view of the relationship between the thickness of the mold a-Si layer and the thickness desired to remain as the passivation film, it can be said that 5 or less is preferable. If the ion energy [keV] is 5 or less, the process is performed with lower energy, and the flatness of the surface of the i-type a-Si layer 102 can be maintained.

It was confirmed that the relationship between the ion energy and the stopping range in the above-described boron (B) was also established for phosphorus (P). Therefore, by utilizing this relationship, the n ⁺ site (B) 104 in FIG. 1 can be formed with good reproducibility. Further, with respect to phosphorus (P), conditions such as the film thickness of the i-type a-Si layer 102 that is an object of forming the n ⁺ site (B) 104 and the flatness of the surface of the i-type a-Si layer 102 From the standpoint of securing, as in the case of boron (B), the same effect as in the case of boron (B) can be obtained by selecting ion energy [keV] of 20 or less and further 5 or less. It is.

FIG. 9 is a graph showing a profile of phosphorus (P) concentration observed in the depth direction of the substrate by changing the ion energy of phosphorus (P).
From this graph, when the ion energy [keV] at the time of ion implantation is changed to 3, 6 and 15, the position [nm] in the depth direction of the substrate where the phosphorus concentration [atoma / cm ³ ] becomes 10 ⁺¹⁸ is , Approximately 30, 43, 78. Accordingly, the n ⁺ site (B) 104 can be formed in the depth direction so that a predetermined phosphorus concentration is obtained at each depth position.

For boron (B), it was confirmed that the same relationship as the profile of phosphorus (P) concentration observed in the depth direction of the substrate in phosphorus (P) described above was established. Therefore, by utilizing this relationship, the p ⁺ site (A) 103 in FIG. 1 can be formed in the depth direction so as to have a predetermined boron concentration.

The ion implantation in the first process and the second process is performed using, for example, an ion implantation apparatus 1200 shown in FIG.
FIG. 11 is a cross-sectional view of an ion implantation apparatus 1200 used in the p-type ion implantation step (fifth step) and the n-type ion implantation step (sixth step) in the present invention. The ion implantation apparatus 1200 includes a vacuum chamber 1201, a permanent magnet 1205, an RF introduction coil 1206, plasma generation means by ICP discharge using an RF introduction window (quartz) 1212, and vacuum exhaust means (not shown).

  The inside of the vacuum chamber 1201 is separated into a plasma generation chamber and a plasma processing chamber by electrodes 1208 and 1209 having a plurality of openings (for example, mesh shape). A substrate support 1204 that supports a substrate (corresponding to the substrate 101 after the texture forming step) 1203 that is an object to be processed is disposed in the plasma processing chamber. Note that the electrode 1208 has a floating potential and has a function of stabilizing the potential of the plasma 1207. The electrode 1209 has a function of extracting a positive ion from the plasma 1207 when a negative potential is applied thereto.

  The inside of the vacuum layer 1201 is decompressed, and a gas containing impurity atoms to be injected into the substrate 1203 is introduced into the plasma generation chamber. Then, the plasma 1207 is excited using plasma generation means, whereby impurity atoms are ionized, and p-type or n-type ions extracted through the electrodes 1208 and 1209 can be implanted into the substrate 1203. .

Here, the implantation amount of the p-type ions and the implantation amount of the n-type ions are determined by the sheet resistance of the n ⁺ portion (B) 104 and the sheet resistance of the p ⁺ portion (A) 103 after annealing, which will be described later, and the HBC. From the relationship with the photoelectric conversion efficiency of the type crystal solar cell, it is determined as the optimum value for manufacturing the solar cell 100. Note that the n-type ion concentration in the n ⁺ region (B) 104 is set to be higher than at least the n-type ion concentration in the substrate 101.

When performing the above-described p-type ion implantation or n-type ion implantation, a process gas in which hydrogen is added to a gas containing impurity atoms (for example, BF ₃ ) is used for the amorphous Si layer. Conditions may be set so that hydrogen is ion-implanted. By implanting hydrogen together with ions during ion implantation, the structural defects of the amorphous Si layer are repaired, the effect of suppressing the recombination of carriers is improved, and the total amount of electrons and holes reaching sites A and B increases. Therefore, the power generation efficiency can be improved.

As a technique for effectively implanting hydrogen into the amorphous Si layer, non-mass-separated ion implantation can be employed. Unlike mass-separated ion implantation in which only n-type ions and p-type ions (for example, P ions and B ions) are separately implanted, non-mass-separated ion implantation uses PH ₃ as a gas containing impurity atoms, A gas containing hydrogen such as BH ₂ is used. As a result, in non-mass-separated ion implantation, hydrogen can be implanted into the substrate simultaneously with n-type ions and p-type ions without using a process gas to which hydrogen is added as described above. Become. Further, non-mass-separated ion implantation does not require a mechanism for separating ions, and thus has an advantage that the footprint of the device structure is reduced.
In this way, by adding hydrogen to the process gas or selecting non-mass-separated ion implantation, the hydrogen implanted into the amorphous Si layer simultaneously with the n-type ions and p-type ions is converted into the amorphous Si layer. It has a concentration distribution in the depth direction.

Next, the annealing process performed through the sixth step is performed using, for example, an annealing apparatus 1300 shown in FIG. An annealing apparatus 1300 of FIG. 12 employs a vertical heating furnace, and is batch-type, and one substrate (a substrate after the p-type and n-type ion implantation steps by the fourth step and the fifth step) is provided in one cassette. A plurality of cassettes can be heat-treated at the same time.
An annealing apparatus 1300 in FIG. 12 includes a heating chamber 1310 and a front chamber 1320, and the internal space 1312 of the heating chamber 1310 and the internal space 1322 of the front chamber 1320 can be shut off by a gate valve 1314.

In an internal space 1322 of the front chamber 1320, a cassette rack 1303 in which a plurality of cassettes 1301 holding the outer peripheral portion of the substrate are stacked in multiple stages so as to be exposed is arranged on the cassette base 1302.
The gate 1314 is opened with the internal space 1312 of the heating chamber 1310 open to the atmosphere, and the cassette base 1302 in this state is moved from the internal space 1322 of the front chamber 1320 to the internal space 1312 of the heating chamber 1310 (not shown). Raise by means (up arrow). Thereafter, the gate valve 1314 is closed, and the internal space 1312 of the heating chamber 1310 is made a reduced pressure atmosphere using the exhaust means (P) 1315. Note that the atmospheric pressure annealing may be performed by introducing an after-mentioned annealing gas as it is without making the internal space 1312 of the heating chamber 1310 a reduced pressure atmosphere.

Thereafter, an annealing gas is introduced into the internal space 1312 of the heating chamber 1310, and an atmospheric pressure annealing process is performed with a predetermined temperature profile in a controlled atmosphere. Here, the introduced gas is nitrogen gas, and hydrogen gas may be added thereto. As described above, by adding hydrogen to the annealing gas, it is possible to compensate for the hydrogen injected into the i-type a-Si layer in the second and third steps from being detached from the substrate by heating. As an example, an annealing gas in which 3% hydrogen is added to nitrogen gas is used.
After the substrate temperature is set to a predetermined temperature or lower, the introduction of the gas is stopped, and the gate valve 1314 is opened with the internal space 1312 of the heating chamber 1310 opened to the atmosphere. Thereafter, the cassette base 1302 is lowered from the internal space 1312 of the heating chamber 1310 to the internal space 1322 of the front chamber 1320 by a moving means (not shown) (downward arrow).

The annealing process of the present invention is performed by the above procedure. At that time, the conditions for the annealing treatment are determined as optimum conditions corresponding to the diffusion coefficients of n-type ions and p-type ions inside the substrate. For example, the annealing temperature is desirably 600 ° C. or lower. This prevents the i-type a-Si layer 102 including the p ⁺ site (A) 103 and the n ⁺ site (B) 104 from being crystallized to deteriorate the function of the i-type a-Si layer as a passivation film. Because. Furthermore, the annealing temperature is more preferably 400 ° C. or lower. This is to prevent hydrogen implanted simultaneously with n-type ions and p-type ions from being separated from the i-type a-Si layer during ion implantation. Moreover, it is desirable that the time required for the annealing treatment is about 30 to 60 minutes.

Next, as an electrode formation step, a metal film (covering the entire outer surface 102b of the i-type a-Si layer including the p ⁺ region (A) 103, the n ⁺ region (B) 104, and the photoresist PR is covered. For example, a Cu film) is formed. As the metal film, an Ag film or the like is preferably used in addition to the Cu film. However, the electrode is not limited to the metal film, and a transparent conductive film may be used instead of the metal film. The metal film or the transparent conductive film is produced using, for example, a general-purpose sputtering apparatus.

Next, the photoresist PR is peeled from the outer surface of the a-Si layer 102 by, for example, irradiating the photoresist PR with UV light through the metal film [ninth step: FIG. 5B]. At that time, the conductive member BM on the photoresist is also removed together.
As a result, the conductive member BM remains on the outer surface of the a-Si layer 102 only in the part formed on the part A and the part B. As a result, an electrode made of the conductive member BM is formed stably so as to cover only the region where the p ⁺ site (A) 103 and the n ⁺ site (B) 104 exist. In the present invention, the ninth step is also referred to as a “lift-off” step.
The HBC crystal solar cell 100I (100) shown in FIG. 1 can be manufactured by sequentially performing the steps described above.

In the case of the first embodiment [HBC type crystalline solar cell 100I (100)], an i-type amorphous material is formed on the surface 101a side of the substrate 101 in the initial stage (before forming the part A and the part B by ion implantation). An n-type amorphous Si layer 113 and an antireflection layer 114 are formed so as to cover the Si layer α.
As described above, by forming the antireflection layer 114 at the initial stage (before forming the part A and the part B by ion implantation), the light incident surface for the handling of subsequent processes such as ion implantation and BM formation is improved. It is preferable in terms of protection.

  FIG. 6 is a flowchart showing the manufacturing process of the solar cell according to the conventional example (FIG. 25), and FIG. 7 is a flowchart showing the manufacturing process of the solar cell according to the present invention (FIG. 1-5).

As shown in FIG. 6, the site | part (A) and site | part (B) in the conventional HBC type | mold crystal-type solar cell are formed for the first time through the process flow of FIG. 25 (a)-FIG. 25 (j). That is, “i-type a-Si film formation, n-type a-Si film formation, photoresist coating / patterning, etching, photoresist peeling, etch stopper filming / patterning, i-type a-Si film formation, p-type a- It is manufactured by sequentially performing 13 processes including “Si film formation, photoresist coating / patterning, etching, photoresist stripping, etch stopper stripping, and i-type a-Si film deposition only on the separated portion”. In the conventional manufacturing method, the coating and peeling processes are required at least three times, and a complicated process flow is required.
On the other hand, as shown in FIG. 7, the site | part (A) and site | part (B) in the HBC type | system | group crystalline solar cell of this invention are formed by the process flow of FIGS. According to the present invention, a simple process flow can be realized because the coating and peeling processes need only be performed once.

  Since the HBC type crystalline solar cell can be manufactured with a very small number of steps compared to the conventional manufacturing method, the HBC type crystalline solar cell of the present invention is more expensive than the conventional step. And etching process "can be greatly reduced. Therefore, according to the present invention, since it is possible to reduce the complicated processes that have been conventionally required, it is possible to manufacture with more stable process management. That is, according to the first embodiment, since an expensive manufacturing apparatus is not required, the present invention contributes to the provision of an inexpensive HBC crystal solar cell.

However, as shown in FIG. 1, in the HBC type crystalline solar cell of the present invention, “p ⁺ site (A) 103” and “n ⁺ site (B) 104” affected by annealing are “i-type a Since it exists inside the “-Si film β102”, it is necessary to consider the annealing conditions.
Specifically, the temperature [° C.] during the annealing treatment is preferably 600 or less in order to prevent the function of the i-type a-Si layer as a passivation film from being lowered, as described above. Furthermore, in order to suppress the detachment | desorption of hydrogen from an i-type a-Si layer, it is preferable that it is 400 or less.

<Second Embodiment> --- Process B
(HBC type crystalline solar cell)
FIG. 13 is a diagram illustrating the configuration of an HBC type crystalline solar cell 200I (200) according to the second embodiment of the present invention. In the structure after manufacture, the HBC crystal solar cell 200I (200) is the same as the HBC crystal solar cell 100I (100) described above, but the manufacturing procedure (manufacturing process) is different between them.

  Specifically, in the case of the first embodiment [HBC type crystalline solar cell 100I (100)], on the one surface 101a side of the substrate 101 in the initial stage (before forming the part A and the part B by ion implantation). The n-type amorphous Si layer 113 and the antireflection layer 114 are formed so as to cover the i-type amorphous Si layer α.

On the other hand, in the case of the second embodiment [HBC type crystalline solar cell 200I (200)], the antireflection layer 214 is not formed in the initial stage (before forming the part A and the part B by ion implantation). . That is, the n-type amorphous Si layer 213 is only formed on the one surface 201a side of the substrate 201 so as to cover the i-type amorphous Si layer α. The antireflection layer 214 of the second embodiment is formed at a later stage (after forming the part A and the part B by ion implantation).
In the second embodiment, since the antireflection layer 214 is formed at a later stage (after forming the part A and the part B by ion implantation), it can be formed simultaneously with the BM by sputtering, which is preferable in terms of productivity improvement. .

(Method for producing HBC type crystalline solar cell)
A method for manufacturing the HBC type crystalline solar cell 200I (200) according to the second embodiment shown in FIG. 13 will be described. 14 to 17 are schematic cross-sectional views showing a procedure for manufacturing the HBC type crystalline solar cell of FIG. FIG. 18 is a flowchart showing manufacturing steps of the HBC type crystalline solar cell shown in FIG. Hereinafter, as in the first embodiment, “amorphous Si” is abbreviated as “a-Si”.
Below, the difference between 1st embodiment and 2nd embodiment is also demonstrated using FIG. 1-5 which shows 1st embodiment, and FIG. 7 suitably.

  Each process for manufacturing the HBC type crystalline solar cell 200 according to the second embodiment will be described in detail. First, in the texture forming step, a wet etching process using, for example, potassium hydroxide (KOH) or sodium hydroxide (NaOH) as an etchant is performed on the substrate 201. Then, organic substances and metal contaminants remaining on the treated substrate 201 are removed using hydrofluoric acid. Thereby, the one surface 201a and the other surface 201b of the substrate 201 are processed into a textured shape [first step: FIG. 14A].

An i-type a-Si film (α) 212 and an i-type a-Si film (β) 202 are respectively formed on the one surface 201a and the other surface 201b of the substrate 201 processed into a shape having the above texture under predetermined conditions. Then, a film is formed by the CVD method [second step: FIG. 14B].
Next, an n-type a-Si film 213 is formed on the i-type a-Si (α) film 212 disposed on the one surface 201a of the substrate 201 by a CVD method under a predetermined condition [third step: FIG. 14 (c)].

The film formation in the second step and the third step is performed using, for example, a manufacturing apparatus (hereinafter also referred to as a CVD apparatus) 700 that forms a film using the CVD method shown in FIG.
In the present embodiment, when the CVD apparatus 700 of FIG. 10 is used, the i-type a-Si film 212, the i-type a-Si film 202, and the n-type a-Si film 213 are passed through each process chamber in order. The substrate 201 is manufactured. That is, in the third step of the second embodiment, the antireflection layer formed in the first embodiment is not formed on the n-type a-Si film 213.

A method of forming three layers using the CVD apparatus 700, that is, “i-type a-Si film 212, i-type a-Si film 202, and n-type a-Si film 213” is the same as in the first embodiment. The description is omitted here.
As shown in FIG. 14C, the CVD apparatus 700 forms an i-type a-Si film (α) 222 and an n-type a-Si film 213 on one surface side, and an i-type a-Si film (β on the other surface side. ) 202 are respectively moved to the film forming outlet chamber (EX) 758, then transferred to the take-out chamber (UL) 760 via the transfer chamber (T) 759, and the inside of the take-out chamber is By setting the atmospheric pressure, it is carried out of the sputtering apparatus.

  Thereafter, a desired photoresist PR is applied on the i-type a-Si film 202 disposed on the other surface 201b of the substrate 201, and then patterned. As a result, in the subsequent step, a photoresist PR having a predetermined opening in the ion implantation region is formed on the i-type a-Si film 202 [fourth step: FIG. 14 (d)].

Next, p-type ions such as boron (B) ions are locally implanted into the vicinity of the outer surface 202b of the i-type a-Si film 202 through the mask M1 [fifth step: FIG. 3A]. To form the p ⁺ site (A) 103 [fifth step: FIG. 15 (c)].
At this time, as shown in FIG. 15B, when the portion A into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion A can be seen. A mask having the shape of the opening is used.

In FIG. 15B, when M1e is defined as the position when the end of the mask M1 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the masks M1 It is designed so that the difference (Δm1A, Δm1B) between M1e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M1, the outer shape of the portion A can be more sharply defined than when only the mask M1 is used. Therefore, according to the present invention, the p ⁺ site (A) 203 can be produced in a clear shape up to the outer edge.

Then, in the outer surface 202b near the i-type a-Si film 202, between and if ^{p +} region (A) 203, and a position which does not overlap with the ^{p +} region (A) 203, phosphorus (P) ions or the like N-type ions are locally implanted through the mask M2 [sixth step: FIG. 16 (a)], thereby forming an n ⁺ portion (B) 204 [sixth step: FIG. 16 (c). ].
At this time, as shown in FIG. 16B, when the portion B into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion B is visible. A mask having the shape of the opening is used.

In FIG. 16B, when M2e is defined as the position when the end of the mask M2 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the mask M2 It is designed so that the difference (Δm1A, Δm1B) between M2e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M2, the outer shape of the portion B can be defined more sharply than when only the mask M2 is used. Therefore, according to the present invention, the n ⁺ site (B) 204 can be manufactured in a clear shape up to the outer edge.

Thus, the same conductivity as that of the first conductivity type of the substrate is present in the i-type a-Si layer (β) 202 and partly exposed on the outer surface side of the a-Si layer (β) 202. An HBC type crystalline solar cell 200G in which a part (A) 203 of a type (for example, n ⁺ type) and a part (B) 204 of a conductivity type different from the first conductivity type are arranged apart from each other is formed. [FIG. 16 (c)]. At this stage, in the i-type a-Si layer (β) 202, the photoresist PR exists on the part (C) that forms the separation part of the part (A) and the part (B).

Next, after the annealing process [seventh step], a conductive member BM functioning as an electrode is formed so as to cover the part A, the part B, and the photoresist PR. The annealing process will be described in detail later.
The conductive member BM is formed by sputtering under a predetermined condition [eighth step: FIG. 17A]. As a result, the conductive member BM formed on the part A and the part B and the conductive member BM formed on the photoresist PR are disconnected.
As the conductive member BM, a material having high conductivity (low resistance) is suitable for use as an electrode, and examples thereof include Ag, Al, Cu, and Ti. The conductive member BM may be a laminated film of two or more layers in addition to a single layer film. A typical example is a laminated film of a transparent conductive film (ITO or the like) and a metal film (Ag or the like).

  Next, after forming the conductive member BM, the antireflection layer 214 is formed. As a result, as shown in FIG. 17A, the HBC type crystalline solar cell 200H (200) of the second embodiment is also i-type amorphous on the one surface 201a side of the substrate 201 as in the first embodiment. An n-type amorphous Si layer 213 and an antireflection layer 214 are formed so as to cover the Si layer (α) 212.

Finally, the photoresist PR is stripped from the outer surface of the a-Si layer 202 by, for example, irradiating UV light [ninth step: FIG. 17B]. At that time, the conductive member BM on the photoresist PR is also removed. As a result, the conductive member BM remains on the outer surface of the a-Si layer 202 only on the part formed on the part A and the part B. Therefore, the conductive member BM along the part A or the part B is formed and can be used as an electrode. This process is a so-called “lift-off” process.
The HBC crystal solar cell 200I (200) having the configuration shown in FIG. 13 can be produced simply by providing the above steps in order.

Also in the HBC type crystalline solar cell 200H (200) of the second embodiment, as in the first embodiment, as shown in FIG. 14B, the i-type a-Si film (β) 202 is originally formed. The film is formed as a single film in the thickness direction and the in-plane direction. For this reason, even when the p ⁺ site (A) 203 and the n ⁺ site (B) 204 are formed in the vicinity of the outer surface 202b of the i-type a-Si film 202 by the subsequent third step and fourth step, they are separated portions. The portion (C), that is, the region where ions are not implanted exists as a single film in the thickness direction.

Furthermore, by forming the p ⁺ part (A) 203 and the n ⁺ part (B) 204 so as not to reach the other surface 201b of the substrate, the i-type a-Si film 202 which is a single film, The i-type a-Si film 202 existing on and in contact with the other surface 201b of the substrate exists as a single film continuous over the in-plane direction of the substrate.
Thus, also in the HBC type crystalline solar cell 200I (200) of the present embodiment (FIG. 13), the i-type a-Si layer 202 is other than the p ⁺ site (A) 203 and the n ⁺ site (B) 204. (Where “single film” means that there is no interface inside the i-type a-Si layer 202), so that the i-type a The function of the -Si film 202 as a passivation film is maintained.

<Third embodiment> --- Process B +
(HBC type crystalline solar cell)
FIG. 19 is a diagram illustrating the configuration of an HBC type crystalline solar cell 300I (300) according to the third embodiment of the present invention. In the structure after manufacture, the HBC type crystalline solar cell 300I (300) includes the above-described HBC type crystalline solar cell 100I (100) and the HBC type crystalline solar cell 200I (200), and “n-type amorphous Si”. It differs in that it does not have a layer. For this reason, 3rd embodiment differs from the manufacturing procedure (manufacturing process) of 1st embodiment or 2nd embodiment. Moreover, the timing which forms an antireflection layer in 3rd embodiment is the same as that of 2nd embodiment.

  Specifically, in the case of the first embodiment [HBC type crystalline solar cell 100I (100)], on the one surface 101a side of the substrate 101 in the initial stage (before forming the part A and the part B by ion implantation). The n-type amorphous Si layer 113 and the antireflection layer 114 are formed so as to cover the i-type amorphous Si layer α.

On the other hand, in the case of the third embodiment [HBC type crystalline solar cell 300I (300)], in the initial stage (before forming part A or part B by ion implantation), the n-type amorphous Si layer or An antireflection layer is not formed. That is, there is nothing that covers the i-type amorphous Si layer α on the one surface 201 a side of the substrate 201. The antireflection layer 314 of the third embodiment is formed so as to cover the amorphous Si layer (α) in a later stage (after forming the part A and the part B by ion implantation).
In the third embodiment, the antireflection layer is formed on the amorphous Si layer (α) at the later stage (after forming the part A and the part B by ion implantation), so that it can be formed simultaneously with the BM by sputtering. This is preferable in terms of improving productivity.

(Method for producing HBC type crystalline solar cell)
A method for manufacturing the HBC type crystalline solar cell 300I (300) according to the third embodiment shown in FIG. 19 will be described. 20 to 23 are schematic cross-sectional views showing a procedure for manufacturing the HBC type crystalline solar cell of FIG. FIG. 24 is a flowchart showing manufacturing steps of the HBC crystal solar cell shown in FIG. Hereinafter, as in the first embodiment, “amorphous Si” is abbreviated as “a-Si”.
Below, the difference between 1st embodiment and 3rd embodiment is also demonstrated using FIGS. 1-5 and FIG. 7 which show 1st embodiment suitably.

  Each process for manufacturing the HBC type crystalline solar cell 300 according to the third embodiment will be described in detail. First, in the texture forming step, a wet etching process using, for example, potassium hydroxide (KOH) or sodium hydroxide (NaOH) as an etchant is performed on the substrate 301. Then, organic substances and metal contaminants remaining on the processed substrate 301 are removed using hydrofluoric acid. Thus, the one surface 301a and the other surface 301b of the substrate 301 are processed into a textured shape [first step: FIG. 20 (a)].

An i-type a-Si film (α) 312 and an i-type a-Si film (β) 302 are formed on the one surface 301a and the other surface 301b of the substrate 301, respectively, which have been processed into a shape having the above texture, under predetermined conditions. Then, a film is formed by the CVD method [second step: FIG. 20B].
Next, an n-type a-Si film 313 is formed on the i-type a-Si (α) film 312 disposed on the one surface 301a of the substrate 301 by a CVD method under a predetermined condition [third step: FIG. 20 (c)].

The film formation in the second step and the third step is performed using, for example, a manufacturing apparatus (hereinafter also referred to as a CVD apparatus) 700 that forms a film using the CVD method shown in FIG.
In the present embodiment, when the CVD apparatus 700 of FIG. 10 is used, the i-type a-Si film (α) 312 and the i-type a-Si film (β) 302 are formed on the substrate by sequentially passing through each process chamber. Prepared on 201. That is, in the third step of the third embodiment, the n-type a-Si film and the antireflection layer formed in the first embodiment are not provided on the i-type a-Si film (α) 312.

A method of forming two layers, that is, “i-type a-Si film 212 and i-type a-Si film 202” using the CVD apparatus 700 is the same as in the first embodiment, and the description thereof is omitted here.
As shown in FIG. 20C, the CVD apparatus 700 formed an i-type a-Si film (α) 322 on one side and an i-type a-Si film (β) 302 on the other side. After the substrate 301 is moved to the film formation outlet chamber (EX) 758, the substrate 301 is moved to the take-out chamber (UL) 760 through the transfer chamber (T) 759, and the inside of the take-out chamber is brought to atmospheric pressure, thereby being sputtered. It is carried out of the device.

  Thereafter, a desired photoresist PR is applied on the i-type a-Si film 302 disposed on the other surface 301b of the substrate 301, and then patterned. As a result, in the subsequent step, a photoresist PR having a predetermined opening in the ion implantation region is formed on the i-type a-Si film 302 [fourth step: FIG. 20D].

Next, p-type ions such as boron (B) ions are locally implanted into the vicinity of the outer surface 302b of the i-type a-Si film 302 through the mask M1 [fifth step: FIG. 21A]. To form a p ⁺ site (A) 303 [fifth step: FIG. 21 (c)].
At that time, as shown in FIG. 21 (b), when the portion A into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion A can be seen. A mask having the shape of the opening is used.

In FIG. 21B, when M1e is defined as the position when the end of the mask M1 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the masks M1 It is designed so that the difference (Δm1A, Δm1B) between M1e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M1, the outer shape of the portion A can be more sharply defined than when only the mask M1 is used. Therefore, according to the present invention, the p ⁺ site (A) 303 can be produced in a clear shape up to the outer edge.

Then, in the outer surface 302b near the i-type a-Si film 302, between and if ^{p +} region (A) 303, and a position which does not overlap with the ^{p +} region (A) 303, phosphorus (P) ions or the like N-type ions are locally implanted through the mask M2 [sixth step: FIG. 22 (a)], thereby forming an n ⁺ portion (B) 304 [sixth step: FIG. 22 (c). ].
At this time, as shown in FIG. 22B, when the portion B into which ions are implanted through the opening of the mask is viewed in plan, the portion of the photoresist PR that defines the outer shape of the portion B is visible. A mask having the shape of the opening is used.

In FIG. 22B, when M2e is defined as the position when the end of the mask M2 is projected onto the photoresist PR, and PRe is defined as the position of the end that defines the opening of the photoresist PR, each of the masks M2 It is designed so that the difference (Δm1A, Δm1B) between M2e and PRe at the end is greater than zero. In the present invention, by using the photoresist PR in addition to the mask M2, the outer shape of the portion B can be defined more sharply than when only the mask M2 is used. Therefore, according to the present invention, the n ⁺ portion (B) 304 can be manufactured in a clear shape up to the outer edge.

As a result, the same conductivity as the first conductivity type of the substrate is present in the i-type a-Si layer (β) 302 and partly exposed to the outer surface side of the a-Si layer (β) 302. An HBC type crystalline solar cell 300G in which a part (A) 303 of a type (for example, n ⁺ type) and a part (B) 304 of a conductivity type different from the first conductivity type are arranged apart from each other is formed. [FIG. 22 (c)]. At this stage, in the i-type a-Si layer (β) 302, the photoresist PR is present on the part (C) that forms the separated portion between the part (A) and the part (B).

Next, after the annealing process [seventh step], a conductive member BM functioning as an electrode is formed so as to cover the part A, the part B, and the photoresist PR. The annealing process will be described in detail later.
The conductive member BM is formed by sputtering under predetermined conditions [eighth step: FIG. 23 (a)]. As a result, the conductive member BM formed on the part A and the part B and the conductive member BM formed on the photoresist PR are disconnected.
As the conductive member BM, a material having high conductivity (low resistance) is suitable for use as an electrode, and examples thereof include Ag, Al, Cu, and Ti. The conductive member BM may be a laminated film of two or more layers in addition to a single layer film. A typical example is a laminated film of a transparent conductive film (ITO or the like) and a metal film (Ag or the like).

  Next, after forming the conductive member BM, the antireflection layer 214 is formed. Accordingly, as shown in FIG. 23A, the HBC crystal solar cell 300H (300) of the third embodiment is changed from the HBC crystal solar cell 200H (200) of the second embodiment to an n-type amorphous. The Si layer is removed, that is, the antireflection layer 314 is formed on the one surface 301 a side of the substrate 301 so as to cover the i-type amorphous Si layer (α) 312.

Finally, the photoresist PR is stripped from the outer surface of the a-Si layer 302 by, for example, irradiating UV light [ninth step: FIG. 23B]. At that time, the conductive member BM on the photoresist PR is also removed. Thereby, the conductive member BM remains on the outer surface of the a-Si layer 302 only in the part formed on the part A or the part B. Therefore, the conductive member BM along the part A or the part B is formed and can be used as an electrode. This process is a so-called “lift-off” process.
The HBC crystal solar cell 300I (300) having the configuration shown in FIG. 19 can be manufactured by simply providing the above steps in order.

Also in the HBC type crystalline solar cell 300H (300) of the third embodiment, as in the first embodiment, as shown in FIG. 20B, the i-type a-Si film (β) 302 is originally formed. The film is formed as a single film in the thickness direction and the in-plane direction. For this reason, even when the p ⁺ site (A) 303 and the n ⁺ site (B) 304 are formed in the vicinity of the outer surface 302b of the i-type a-Si film 302 in the subsequent third and fourth steps, the separation portion is a separation portion. The portion (C), that is, the region where ions are not implanted exists as a single film in the thickness direction.

Furthermore, by forming the p ⁺ part (A) 203 and the n ⁺ part (B) 304 so as not to reach the other surface 301b of the substrate, the i-type a-Si film 302 that is a single film is formed. The i-type a-Si film 302 that is in contact with the other surface 301b of the substrate exists as a single film that is continuous over the in-plane direction of the substrate.
Thus, also in the HBC type crystalline solar cell 300I (300) of the present embodiment (FIG. 19), the i-type a-Si layer 302 is other than the p ⁺ site (A) 303 and the n ⁺ site (B) 304. (Where “single film” means that no interface exists inside the i-type a-Si layer 302), so that the i-type a The function of the Si film 302 as a passivation film is maintained.

  The present invention is widely applicable to HBC type crystalline solar cells. Such an HBC type crystalline solar cell is suitably used as a solar cell of a type that is required to be light in operating conditions in addition to high power generation efficiency per unit area, for example.

  BM conductive part, PR photoresist, 100 HBC type crystalline solar cell, 101 substrate, 101a one side, 101b other side, 102 i-type amorphous Si layer (β), 103 part A, 104 part B, 112 i-type Amorphous Si layer (α), 113 n-type amorphous Si layer, 114 antireflection layer.

Claims (6)

A method of manufacturing an HBC type crystalline solar cell,
Using a substrate made of crystalline silicon of the first conductivity type,
Forming an i-type amorphous Si layer α covering one surface on which light is incident on the substrate and an i-type amorphous Si layer β covering another surface located on the opposite side of the one surface individually or simultaneously When,
Forming a photoresist so as to cover a region of the outer surface of the amorphous Si layer β in which impurities are not introduced in a subsequent step;
A portion A of the same conductivity type as the first conductivity type is formed by an ion implantation method using a mask so as to be inherent in the amorphous Si layer β and partially exposed to the outer surface side of the amorphous Si layer β. And forming a portion B of a conductivity type different from the first conductivity type at a position spaced apart from each other by the photoresist;
Annealing the amorphous Si layer β after the ion implantation;
Forming a conductive member so as to cover the part A, the part B, and the photoresist located on the outer surface side of the amorphous Si layer β;
Removing the photoresist coated with the conductive member;
In order. The manufacturing method of the HBC type | mold crystal-type solar cell characterized by the above-mentioned. A mask having a shape of an opening so that the portion of the photoresist defining the outer shape of the portion A or the portion B can be seen when the portion A or the portion B into which ions are implanted through the opening of the mask is viewed in plan Use
The manufacturing method of the HBC type | mold crystal solar cell of Claim 1 characterized by the above-mentioned.   Before the step of forming the photoresist, a step of forming an n-type amorphous Si layer so as to cover the i-type amorphous Si layer α, and a SiN layer so as to cover the n-type amorphous Si layer The method of manufacturing an HBC type | system | group crystalline solar cell of Claim 1 or 2 provided with the process of forming in order.   Before the step of forming the photoresist, the step of forming an n-type amorphous Si layer so as to cover the i-type amorphous Si layer α is performed after the step of forming the conductive member. 3. The method of manufacturing an HBC type crystalline solar cell according to claim 1, further comprising a step of forming a SiN layer so as to cover the amorphous Si layer of the type. 4.   The HBC type crystal according to claim 1, further comprising a step of forming a SiN layer so as to cover the i-type amorphous Si layer α after the step of forming the conductive member. Of the solar cell solar cell. HBC type crystalline solar cell,
A substrate made of crystalline silicon of the first conductivity type that exhibits a photoelectric conversion function;
An i-type amorphous Si layer α disposed so as to cover one surface on which light is incident on the substrate;
An i-type amorphous Si layer β disposed so as to cover the other surface located on the side opposite to the one surface of the substrate,
The portion A of the same conductivity type as the first conductivity type and the conductivity different from the first conductivity type so as to be inherent in the amorphous Si layer β and partially exposed to the outer surface side of the amorphous Si layer β. The mold parts B are spaced apart from each other,
The HBC type crystalline solar cell, wherein electrodes made of conductive members are disposed so as to individually cover the exposed outer surfaces of the part A and the part B, respectively.

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