TW201836164A - Solar cell and solar module - Google Patents

Abstract

The present invention comprises: a rear surface passivation film that is formed on the rear surface of the silicon substrate; a plurality of contact holes (7) that pass through the rear surface passivation film and reach a surface layer of the rear surface of the silicon substrate from the surface of the rear surface passivation film; a plurality of first rear surface electrodes that are provided along a first direction on the rear surface passivation film and are used for connecting strip-like tab lines along the first direction; and a rear surface collector electrode that connects the silicon substrate inside the contact holes (7) and the first rear surface electrodes. A solar cell (10) is provided with the contact holes (7), avoiding areas neighboring the first rear surface electrodes in the first direction.

Description

 Solar battery unit and solar battery module  

The invention relates to a solar cell unit and a solar cell module.

Conventionally, in a solar cell, a special film called a passivation film is used for the purpose of suppressing the carrier recombination speed of the surface on the light-receiving surface side of the ruthenium substrate. The passivation film has a relationship between the passivation film and the ruthenium, or a treatment before and after the formation of the film by the passivation film, so that the dangling bonds are terminated, thereby directly reducing the recombination center in the interface between the ruthenium substrate and the passivation film. Features. Further, the passivation film has a function of suppressing the recombination speed by an electric field effect by causing a fixed charge at the interface between the ruthenium substrate and the passivation film to generate an electric field barrier at the interface.

In recent years, as shown in the patent document 1, it is known that a passivation film is provided on the non-light-receiving surface side of the solar cell, that is, a PERC (Passivated Emitter and Rear Cell) structure having improved characteristics on the back side. In this way, further improvement in characteristics is achieved. In a P-type solar cell using a P-type germanium substrate, alumina (Al ₂ O ₃ ) is used for the back passivation film, and a tantalum nitride film (SiN film) or hafnium oxynitride is used for the cap film for protecting the back passivation film. A film such as a film (SiON).

 [Previous Technical Literature]    [Patent Literature]  

[Patent Document 1] Japanese Patent No. 5924945

However, as shown in the above Patent Document 1, when a passivation film is provided on the back surface of the solar cell, in order to obtain a good passivation effect on the back side of the ruthenium substrate, it is necessary to provide a hole in the passivation film and also to provide a back surface on the ruthenium substrate. hole.

When the solar cell module is constructed, the electrodes of adjacent solar cells are electrically joined to each other by tabs. Here, when the electrode of the solar cell unit is connected to the pole piece, residual thermal stress due to heating of the pole piece connection process is applied to the solar cell unit. Then, since the residual thermal stress is applied to the portion of the hole provided on the back surface of the ruthenium substrate, the ruthenium substrate of the solar cell unit is cracked from the portion of the hole as a starting point, which not only causes deterioration in manufacturing yield when the solar cell module is manufactured, but also When the external force is applied to the solar cell module, the output of the solar cell module is lowered, and the reliability of the solar cell module is lowered.

The present invention has been made in view of the above circumstances, and an object thereof is to achieve an improvement in characteristics of a solar cell unit by a back passivation film, and to suppress occurrence of a malfunction due to connection of a tab wire of a solar cell unit. Solar battery unit.

In order to achieve the above object, in order to achieve the object, a solar cell unit of the present invention includes: a first conductivity type germanium substrate; a back surface passivation film formed on a back surface of the germanium substrate facing the light receiving surface; and a plurality of contact holes through the back surface passivation a film, wherein a surface of the back surface passivation film reaches a surface layer of the back surface of the substrate; and a plurality of first back electrodes are arranged on the back surface passivation film along the first direction to connect the strip-shaped tab lines along the first direction; And the second back electrode, the germanium substrate in the contact hole is connected to the first back electrode. The solar battery unit is provided with a contact hole in a region adjacent to the first back surface electrode in the first direction.

The solar cell unit of the present invention has a solar cell unit that achieves improvement in characteristics of the solar cell unit by the back passivation film and suppresses occurrence of a problem due to connection of the tab wire of the solar cell unit. effect.

1, 11‧‧‧ semiconductor substrate

1H, 5H, 6H, 7‧‧ contact holes

2‧‧‧Micro bumps

3‧‧‧n type impurity diffusion layer

3a‧‧‧phosphorus glass layer

4‧‧‧Anti-reflection film

5‧‧‧Back passivation film

6‧‧ ‧ cover film

8‧‧‧Back surface layer

10‧‧‧Solar battery unit

10A‧‧‧The light-receiving surface of the solar cell unit

10B‧‧‧Back of the solar cell unit

11A‧‧‧Light-receiving surface of semiconductor substrate

11B‧‧‧Back of the semiconductor substrate

12‧‧‧Photometric surface electrode

12B‧‧‧Lighted surface bus electrode

12G‧‧‧light-receiving gate electrode

13‧‧‧Back electrode

13a‧‧‧Back collector electrode

13b‧‧‧Back joint electrode

13s‧‧‧A pair of sides

14‧‧‧Connector wire connection area

14a‧‧‧1st area

14b‧‧‧2nd area

15‧‧‧ Damage layer

16a‧‧‧Back bonding electrode material paste

16b‧‧‧Backside collector electrode material paste

16c‧‧‧Stained surface electrode material paste

20‧‧‧Connector

25‧‧‧ transverse joint line

26‧‧‧Output connector line

31‧‧‧Lighted protective material

32‧‧‧Back protective material

33‧‧‧Light-receiving sealing materials

34‧‧‧Back side sealing material

40‧‧‧Frame

50‧‧‧Solar battery array

70‧‧‧Solar battery array

100‧‧‧Solar battery module

200‧‧‧heating tools

Fig. 1 is a perspective view of a solar battery module according to an embodiment of the present invention viewed from a light receiving surface side.

Fig. 2 is an exploded perspective view of the solar battery module according to the embodiment of the present invention viewed from the light receiving surface side.

Fig. 3 is a cross-sectional view of an essential part of a solar battery module according to an embodiment of the present invention.

Fig. 4 is a perspective view of the solar cell array according to the embodiment of the present invention viewed from the back side.

Fig. 5 is a perspective view of the solar battery array according to the embodiment of the present invention viewed from the light receiving surface side.

Fig. 6 is a perspective view of the solar battery array according to the embodiment of the present invention viewed from the back side.

Fig. 7 is a plan view showing the solar battery cell of the embodiment of the present invention viewed from the light receiving surface side.

Fig. 8 is a plan view of the solar battery cell of the embodiment of the present invention viewed from the back side facing the light-receiving surface side.

Fig. 9 is a cross-sectional view showing the configuration of a solar battery cell according to an embodiment of the present invention, and a cross-sectional view of an essential part taken along line IX-IX in Fig. 8.

Fig. 10 is a cross-sectional view showing the configuration of a solar battery cell according to an embodiment of the present invention, and a cross-sectional view of an essential part in the X-X line in Fig. 8.

Fig. 11 is an enlarged view of a main part of a back surface of a solar battery cell according to an embodiment of the present invention.

Fig. 12 is a flow chart showing the procedure of a method of manufacturing a solar battery cell according to an embodiment of the present invention.

Fig. 13 is a conceptual view showing the existence of a damaged layer in a semiconductor substrate made of boron-doped p-type germanium in the embodiment of the present invention.

Fig. 14 is a conceptual diagram showing a state in which a damaged layer existing on the surface of a semiconductor substrate is removed in the embodiment of the present invention.

Fig. 15 is a schematic cross-sectional view showing a texture etching process for forming a texture structure on the surface of a semiconductor substrate in the embodiment of the present invention.

Fig. 16 is a schematic cross-sectional view showing an impurity diffusion step of forming an n-type impurity diffusion layer on a semiconductor substrate in the embodiment of the present invention.

Fig. 17 is a schematic cross-sectional view showing a planarization step on the back side of the semiconductor substrate in the embodiment of the present invention.

Fig. 18 is a schematic cross-sectional view showing a step of forming a back surface passivation film and a cap film on the back surface of a semiconductor substrate in the embodiment of the present invention.

Fig. 19 is a schematic cross-sectional view showing a step of forming an anti-reflection film on the light-receiving surface side of the semiconductor substrate in the embodiment of the present invention.

Fig. 20 is a schematic cross-sectional view showing a step of forming a contact hole on the back side of the semiconductor substrate in the embodiment of the present invention.

Fig. 21 is a schematic plan view showing a region in which a contact hole is formed in the back side of the semiconductor substrate in the embodiment of the present invention.

Fig. 22 is a schematic cross-sectional view showing a step of printing an electrode material paste for forming a light-receiving surface electrode and a back surface electrode on the front and back surfaces of a semiconductor substrate in the embodiment of the present invention.

Fig. 23 is a schematic cross-sectional view showing a step of simultaneously baking the electrode material paste to form a light-receiving surface electrode and a back surface electrode in the embodiment of the present invention.

Fig. 24 is a schematic view showing a bonding wire bonding step of electrically connecting the light-receiving surface electrode and the back surface electrode to the tab wire in the embodiment of the present invention.

Fig. 25 is a perspective view showing a solar battery array in the embodiment of the present invention.

Hereinafter, the solar battery cell and the solar battery module according to the embodiment of the present invention will be described in detail based on the drawings. However, the present invention is not limited by the embodiment, and may be appropriately modified without departing from the spirit and scope of the invention. Further, in the drawings shown below, in order to facilitate understanding, there are cases where the scales of the respective layers or members are different from the actual ones, and the same applies to the respective drawings.

Implementation form.

Fig. 1 is a perspective view of a solar battery module 100 according to an embodiment of the present invention viewed from a light receiving surface side. Fig. 2 is an exploded perspective view of the solar battery module 100 according to the embodiment of the present invention viewed from the light receiving surface side. Fig. 3 is a cross-sectional view of a principal part of a solar battery module 100 according to an embodiment of the present invention. In the solar battery module 100 of the present embodiment, as shown in FIGS. 1 to 3, the light-receiving surface side of the solar cell array 70 is covered by the light-receiving surface side sealing material 33 and the light-receiving surface protective material 31, and the solar cell array 70 is placed. The back side facing the light-receiving surface is covered with the back side seal member 34 and the back surface protective member 32, and the outer peripheral edge portion is surrounded by the reinforcing frame 40.

Fig. 4 is a perspective view of the solar cell array 70 of the embodiment of the present invention viewed from the back side. Fig. 5 is a perspective view of the solar battery array 50 of the embodiment of the present invention viewed from the light receiving surface side. Fig. 6 is a perspective view of the solar battery array 50 of the embodiment of the present invention viewed from the back side. Fig. 7 is a plan view showing the solar battery cell 10 of the embodiment of the present invention viewed from the light receiving surface side. Fig. 8 is a plan view of the solar battery cell 10 according to the embodiment of the present invention viewed from the back side facing the light-receiving surface side. In Fig. 8, an example of the position at which the joint wire 20 is joined is indicated by a broken line.

As shown in Fig. 4, the solar cell array 70 is composed of a plurality of solar cell arrays 50 which are electrically and mechanically connected in series or in parallel with the horizontal joint line 25 and the output joint line 26.

Further, as shown in FIGS. 3 to 6, the solar battery array 50 is configured such that the plurality of solar battery cells 10 arranged in a quadrangular shape are electrically and mechanically connected in series by the joint wires 20. The plurality of solar battery cells 10 are connected in series in the first direction, that is, the X direction in the drawing, by the joint wires 20 as shown in Figs. 3 to 6 . The first direction is the direction in which the plurality of solar cells 10 are connected by the tab wire 20.

The solar cell unit 10 is on the light-receiving surface 11A side of the semiconductor substrate 11 which is a first main surface of the semiconductor substrate 11 which is formed of a p-type single crystal germanium substrate in which a p-type single crystal germanium substrate is formed by forming an n-type impurity diffusion layer. A textured shape is formed by texture etching to increase the etendue of light. Here, the outer shape of the semiconductor substrate 11 has a square shape in the surface direction of the semiconductor substrate 11. The n-type impurity diffusion layer is formed on the light-receiving surface 11A side of the semiconductor substrate. Next, a tantalum nitride film as an anti-reflection film is formed on the light-receiving surface 11A of the semiconductor substrate. In addition, the illustration of the uneven shape and the anti-reflection film is abbreviate|omitted in the drawing. Further, in the solar battery cell 10, the light-receiving surface electrode 12 is formed on the light-receiving surface 11A side of the semiconductor substrate, and the back surface electrode 13 is formed on the second main surface of the semiconductor substrate 11, that is, the back surface 11B side of the semiconductor substrate.

On the light-receiving surface 10A side of the solar battery cell, as shown in FIGS. 5 and 7 , a light-receiving surface collector electrode that concentrates electrons generated by photo-electron conversion, that is, a plurality of light-receiving surface gate electrodes 12G is formed. And a light-receiving surface bonding electrode that is a bonding surface of the bonding wire 20, that is, the light-receiving surface bus bar electrode 12B. The light-receiving surface electrode 12G is an electrode for concentrating a photocurrent, and is formed by arranging a plurality of thin linear electrodes in parallel in order to concentrate the photocurrent without hindering the sunlight from reaching the inside of the solar cell unit 10.

In addition, as shown in FIG. 7, the light-receiving surface bus bar electrode 12B is formed in four rows in a line shape along the substantially entire length of the solar cell unit 10 along the first direction in which the solar cell unit 10 is connected. In other words, the light-receiving surface bus bar electrode 12B is connected to all of the light-receiving surface gate electrodes 12G in a direction orthogonal to the light-receiving surface gate electrode 12G. For the sake of convenience, in the first, second, fourth, and fifth figures, the case where the light-receiving surface bus bar electrodes 12B are two rows is shown. The light-receiving surface bus electrode 12B is an electrode for electrically connecting to the tab wire 20. The light-receiving surface bus electrode 12B and the light-receiving surface gate electrode 12G are formed by applying a conductive paste having metal particles to a desired range and baking.

On the back surface 10B side of the solar cell, as shown in FIGS. 6 and 8, a back surface collector electrode 13a containing aluminum (Al) and a back surface bonding electrode 13b containing silver (Ag) are formed to constitute the back surface electrode 13. The back surface collector electrode 13a covers a substantially entire area of the back surface 10B of the solar cell unit in order to form a back surface electric field layer (not shown) for raising the open voltage and the short-circuit current, and an electrode for collecting the current on the back side.

Further, the back surface bonding electrode 13b is an electrode provided by taking out a hole collected by the back surface collecting electrode 13a to the outside and making contact with the external electrode. That is, the back surface bonding electrode 13b is an electrode provided for electrically bonding to the tab wire 20. Similarly to the light-receiving surface bus bar electrode 12B, the back surface bonding electrode 13b is provided along the first direction of the connection direction of the solar battery cells 10. Next, the back surface bonding electrode 13b is disposed at a position facing the light receiving surface bus bar electrode 12B with the semiconductor substrate 11 interposed therebetween.

The back surface bonding electrode 13b of the present embodiment is formed in four rows in a stepping stone shape throughout the entire length of the solar cell unit 10 along the first direction along the direction in which the solar cell unit 10 is connected, as shown in Fig. 8. By forming the back surface bonding electrode 13b in a stepping stone shape, the amount of silver used can be suppressed and the manufacturing cost can be suppressed. As described above, the back surface collector electrode 13a and the back surface bonding electrode 13b are formed by applying a conductive paste having metal particles such as Al or Ag to a desired range and baking.

Fig. 9 is a cross-sectional view showing the configuration of a solar cell unit 10 according to an embodiment of the present invention, and a cross-sectional view of an essential part taken along line IX-IX in Fig. 8. Fig. 10 is a cross-sectional view showing the configuration of a solar cell unit 10 according to an embodiment of the present invention, and a cross-sectional view of an essential part taken along the line X-X in Fig. 8. Here, in the ninth and tenth drawings, the tab line 20 connected to the solar cell unit 10 is also shown.

In the solar cell unit 10, an impurity diffusion layer which is an impurity diffusion layer which diffuses n-type impurities by phosphorus diffusion is formed on the surface of the semiconductor substrate 1 which is a p-type 第 which is a first conductivity type, that is, an n-type impurity. The impurity diffusion layer 3 is formed with an anti-reflection film 4 made of a tantalum nitride film.

A p-type single crystal or polycrystalline germanium substrate can be used as the semiconductor substrate 1. However, the semiconductor substrate 1 is not limited thereto, and an n-type germanium substrate may be used. Further, a tantalum oxide film may be used for the anti-reflection film 4. In addition, fine irregularities are formed on the surface of the solar cell unit 10 on the light-receiving surface side of the semiconductor substrate 1 as a texture structure. The fine concavities and convexities are formed to increase the area of light from the outside on the light-receiving surface, suppress the reflectance in the light-receiving surface, and close the light. In addition, in FIG. 9 and FIG. 10, illustration of a micro unevenness is abbreviate|omitted for convenience.

Further, on the light-receiving surface side of the semiconductor substrate 1, the above-mentioned light-receiving surface electrode 12 passes through the anti-reflection film 4 and is electrically connected to the n-type impurity diffusion layer 3. The light-receiving surface electrode 12 is provided with a plurality of elongated elongated light-receiving surface gate electrodes 12G in the in-plane direction of the light-receiving surface of the semiconductor substrate 1, and a light-receiving surface that is electrically connected to the light-receiving surface gate electrode 12G is converged. The drain electrode 12B is provided so as to be orthogonal to the light-receiving surface gate electrode 12G in the in-plane direction of the light-receiving surface of the semiconductor substrate 1, and is electrically connected to the n-type impurity diffusion layer 3 on the bottom surface portion.

The longitudinal direction of the light-receiving surface bus bar electrode 12B is the same direction as the first direction, and is the connection direction of the plurality of solar battery cells 10 connected by the tab wire 20. Further, the longitudinal direction of the light-receiving surface bus bar electrode 12B is formed in the same direction as the second direction orthogonal to the first direction in the plane of the semiconductor substrate 1. When the solar cell module 10 is used to manufacture the solar cell module in the light-receiving surface electrode 12 on the light-receiving surface electrode 12B, the joint wire 20 is welded as shown in Figs. 9 and 10 . In addition, in the ninth diagram and the tenth diagram, only the light-receiving surface bus bar electrode 12B is displayed in the light-receiving surface electrode 12.

On the other hand, the surface of the semiconductor substrate 1 facing the light-receiving surface, that is, the back surface, is provided with a back surface passivation film 5 made of alumina (Al ₂ O ₃ ) having a thickness of about 5 nm to 20 nm; And a cap film 6 of the back passivation film 5 is formed of a hafnium oxynitride film (SiON) having a film thickness of about 100 nm to 150 nm. Among them, a tantalum nitride film (SiN film) may be used for the cover film 6. The cover film 6 is provided with a dot-shaped contact hole 6H penetrating in the thickness direction. Further, the back surface passivation film 5 is provided in a lattice shape in which the contact holes 5H which are extended by the contact holes 6H to reach the back surface of the semiconductor substrate 1 are arranged. Further, the contact hole 5H is extended to the surface layer of the back surface of the semiconductor substrate 1, and the dot-shaped contact hole 1H is arranged in a lattice shape.

Next, the contact holes 7 arranged in a lattice shape are formed by the contact holes 6H, the contact holes 5H, and the contact holes 1H. The contact hole 7 is formed in a circular shape along a cross section in the plane of the semiconductor substrate 1. However, if the cover film 6 is not formed, the contact hole 7 is formed by the contact hole 5H and the contact hole 1H. Further, the contact holes 7 are formed in a circular shape having a diameter of about 20 nm to 100 nm at intervals of 0.5 mm to 1 mm. Further, the cross section of the contact hole 7 along the in-plane of the semiconductor substrate 1 is not limited to a circular shape.

Further, on the back surface of the semiconductor substrate 1, the back surface electrode 13 and the back surface of the semiconductor substrate 1 are electrically connected to each other. The back surface electrode 13 is provided with a buried contact hole 7, and the back surface collector electrode 13a of the back surface passivation film 5 is entirely covered in the in-plane direction of the back surface passivation film 5. Further, on the back surface of the semiconductor substrate 1, a back surface bonding electrode 13b surrounded by the back surface collector electrode 13a and electrically connected to the back surface collector electrode 13a is provided. The back surface collector electrode 13a is formed in contact with the contact hole 1H at a point where it is electrically connected to the back surface of the semiconductor substrate 1. The electrode 13b is bonded to the back surface of the back electrode 13, and when the solar cell module 100 is manufactured, as shown in Figs. 9 and 10, the tab wire 20 is welded.

The solar battery cell 10 of the present embodiment has a thickness of 200 μm, a vertical width of 156 mm, and a banner of 156 mm. The light-receiving surface bus bar electrode 12B has a width of 1 mm and a length of 155 mm, and four of them are arranged at intervals of 39 mm on the light-receiving surface side of the solar battery cell 10. The light-receiving surface electrode 12G has a width of 50 μm to 100 μm and a length of 155 mm, and a direction orthogonal to the longitudinal direction of the light-receiving surface bus bar electrode 12B is a longitudinal direction, and is arranged at an interval of 1 mm to 2 mm at equal intervals. 156 to 78.

The back surface bonding electrode 13b has a square shape having a width of 2 mm and a length of 2 mm, and is disposed at a position corresponding to the light-receiving surface bus bar electrode 12B on the back surface side of the solar battery cell 10 so as to be long-side with the light-receiving surface bus bar electrode 12B. The direction in which the directions are parallel is a columnar shape in the longitudinal direction, and in every other row, 6 to 10 are arranged in four rows at intervals of 26 mm to 15 mm.

Further, in the surface layer of the back surface of the semiconductor substrate 1 which is in contact with the back surface collector electrode 13a, a p+ region in which the aluminum is diffused to the surface layer on the back side of the semiconductor substrate 1 at a high concentration is formed by the back surface collector electrode 13a. That is, the back surface field (BSF: Back Surface Field) 8. That is, the BSF layer 8 is formed in a region adjacent to the contact hole 1H in the surface layer of the back surface of the semiconductor substrate 1. On the back side of the semiconductor substrate 1, the electric power generated by the solar battery cell 10 flows through the semiconductor substrate 1 in the path of the BSF layer 8, the back surface collector electrode 13a, and the back surface bonding electrode 13b.

Fig. 11 is an enlarged view of a main part of the back surface of the solar battery cell 10 according to the embodiment of the present invention. In the solar battery cell 10, the contact hole 7 is provided in a region other than the tab wire connecting region 14 in the back surface of the semiconductor substrate 1 as shown in Fig. 8. That is, in the solar cell unit 10, the contact line 7 is not provided in the tab line connecting region 14 on the back side.

The tab line connection region 14 is provided over a predetermined area of the back surface of the semiconductor substrate 1 to which the tab line 20 is connected or a region where the tab line 20 is highly connected, and is provided over the entire length of the banner of the solar cell unit 10. The area where the possibility of connecting the joint wire 20 is high is a region where the joint wire 20 is highly likely to be connected when the joint wire 20 is displaced by a predetermined joint position. The tab wire connection region 14 is on the back surface of the semiconductor substrate 1, and is provided in a width of 2 mm × a length of 156 mm, for example, and is provided at four intervals of 39 mm. Here, in FIG. 8, for the sake of convenience, the tab wire connection region 14 includes a region exceeding the banner in the back surface of the semiconductor substrate 1 and is shown by a broken line.

As shown in Fig. 11, the tab wire connecting region 14 includes a first region 14a which is a region adjacent to the back surface bonding electrode 13b in the first direction, and a W when the width of the tab wire 20 is W. In the second direction in which the back surface of the solar battery cell 10 is perpendicular to the first direction, the second region 14b is a region within a range of a distance of W/2 from a pair of sides along the first direction. The Y direction in the second direction diagram is the width direction of the back surface bonding electrode 13b.

When the solar cell module 100 is manufactured by connecting the electrode of the solar battery cell 10 to the terminal wire 20, as shown in Figs. 9 and 10, the tab wire 20 is welded to the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b. Next, residual thermal stress occurs in the solar cell unit 10 due to heating in the soldering process of the tab wire 20. The residual thermal stress occurs due to the difference in heat shrinkage between the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b and the tab wire 20 during cooling after heating, and thus occurs in the vicinity of the back surface bonding electrode 13b and the light-receiving surface bus bar electrode 12B. nearby. The thickness of the semiconductor substrate 11 is about 200 μm, which is very small compared with the arrangement interval of the back surface bonding electrode 13b, and the residual thermal stress is not alleviated by the thickness of the semiconductor substrate 11, and is also transmitted to the back surface side of the semiconductor substrate 11.

Further, in order to connect the solar battery cells 10 to each other by the tab wire 20, the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b are disposed at positions corresponding to the surface of the semiconductor substrate 1. Therefore, the vicinity of the back surface bonding electrode 13b on the back surface side of the semiconductor substrate 1 is affected by the residual thermal stress occurring in the vicinity of the back surface bonding electrode 13b when the tab wire 20 is connected, and is applied to the light receiving surface busbar when the tab wire 20 is connected. A large amount of residual thermal stress is applied by the influence of residual thermal stress in the vicinity of the electrode 12B. The tab line connection region 14 including the first region 14a and the second region 14b on the back surface side of the semiconductor substrate 1 is particularly susceptible to the residue from the back surface side of the semiconductor substrate 1 to the tab line 20 of the back surface bonding electrode 13b. The influence of the thermal stress and the influence of the residual thermal stress on the connection of the tab wire 20 of the light-receiving surface bus bar electrode 12B.

When the residual thermal stress applies thermal stress to the portion of the contact hole 1H provided on the back surface of the solar cell unit 10, a crack originating from the contact hole 1H occurs in the semiconductor substrate 1. Then, the occurrence of the crack not only causes deterioration in the manufacturing yield at the time of manufacture of the solar cell module 100, but when the external force is applied to the solar cell module 100 constituted by the solar cell unit 10, the solar cell module 100 is caused. The decrease in output due to the decrease in strength causes a decrease in the reliability of the solar cell module 100.

Therefore, in the present embodiment, the contact hole 7 is more specifically referred to as the contact hole 1H, and is provided in a region other than the tab line connecting region 14 on the back surface of the semiconductor substrate 1, whereby the bus bar electrode 12B on the light receiving surface can be suppressed. The influence of residual thermal stress occurring in the vicinity of the vicinity and back surface bonding electrodes 13b on the contact hole 1H. In other words, in the solar battery cell 10, the influence of the residual thermal stress caused by the connection of the tab wire 20 of the back surface bonding electrode 13b and the connection of the tab wire 20 to the light-receiving surface bus bar electrode 12B are caused. The contact line connection region 14 in the vicinity of the back surface bonding electrode 13b which is affected by the residual thermal stress is not provided with the contact hole 1H.

Thereby, the solar cell unit 10 can suppress the influence of residual thermal stress generated in the vicinity of the light-receiving surface bus bar electrode 12B and the vicinity of the back surface bonding electrode 13b, and thermal stress is applied to the contact hole 1H provided on the back surface of the semiconductor substrate 1. In part, the solar cell unit 10 is cracked. Therefore, the solar battery unit 10 can suppress the deterioration of the manufacturing yield of the solar battery cell 10 and the decrease in the output of the solar battery module 100 due to the influence of the residual thermal stress generated in the vicinity of the light-receiving surface bus bar electrode 12B. In other words, by providing the contact hole 7 in a region other than the tab wire connecting region 14 on the back surface of the semiconductor substrate 1, the influence of the residual thermal stress caused by the connection of the tab wire 20 on the contact hole 1H can be suppressed, and the effect can be suppressed. The contact hole 1H is the occurrence of a crack of the starting point.

Here, since the residual thermal stress is generated directly above the joint wire 20, it is preferable that the contact hole 7 is not provided. Therefore, it is preferable that the first region 14a, which is the region adjacent to the back surface bonding electrode 13b in the first direction, is not provided with the contact hole 7. In other words, the contact hole 7 is preferably formed so as to avoid the first region 14a which is a region adjacent to the back surface bonding electrode 13b in the first direction.

Further, in the connection of the tab wire 20, there is a case where the position of the tab wire 20 is shifted by a predetermined connection position. It is preferable to selectively form the contact hole 7 in consideration of the positional deviation of the tab wire 20 as shown above. Regarding the positional displacement of the tab wire 20, in consideration of the current collecting effect from the back surface bonding electrode 13b, it is preferable to perform solder bonding to the back surface bonding electrode 13b in a region of half or more of the width direction of the tab wire 20. When the width of the tab wire 20 is set to W, the non-contact hole region where the contact hole 7 is not formed is preferably formed in a range of W/2 in consideration of the positional deviation of the tab wire 20. In other words, when the width of the tab wire 20 is W, the second direction orthogonal to the first direction in the plane of the back surface of the solar cell unit 10 is as shown in FIG. It is preferable that the region in the range of 13 s and 13 s is a distance of W/2, that is, the second region 14 b is not provided with the contact hole 7 . In other words, the contact hole 7 is preferably formed so as to avoid the second region 14b which is a region adjacent to the back surface bonding electrode 13b in the first direction.

Further, in the solar battery cell 10, in order to secure a wide light-receiving area, the width of the light-receiving surface bus bar electrode 12B and the width of the tab wire 20 are formed to have the same width, for example, 1 mm wide. On the other hand, the width of the back surface bonding electrode 13b is formed to have a width wider than the width of the tab wire 20 by about 1 mm in consideration of the manufacturing precision of the back surface bonding electrode 13b and the tab wire 20, and is formed, for example, to a width of about 2 mm. Next, at this time, as shown in FIG. 11, when the width of the tab wire 20 is W, the width of the back surface bonding electrode 13b in the second direction is 2 W, and the contact hole 7 is not provided in the second direction. The center position C of the back surface bonding electrode 13b is in the range of the distance of W. That is, not only the predetermined region of the tab wire 20 is connected to the back surface of the semiconductor substrate 1, but also the contact hole 7 is not provided in a region where the tab wire 20 is highly connected when the tab wire 20 is displaced by a predetermined connection position. Therefore, even in the case where the joint wire 20 is connected by a predetermined joint positional position, the above effects can be obtained.

Next, a method of manufacturing the solar cell module 100 of the present embodiment described above will be described.

(production of solar cell unit)

First, the solar cell unit 10 is fabricated. Fig. 12 is a flow chart showing the procedure of a method of manufacturing the solar battery cell 10 according to the embodiment of the present invention. Figs. 13 to 20, 22, and 23 are cross-sectional views showing a method of manufacturing the solar battery cell 10 according to the embodiment of the present invention. Fig. 21 is a schematic plan view showing a region in which a contact hole is formed in the back side of the semiconductor substrate in the embodiment of the present invention.

Fig. 13 is a conceptual view showing the existence of the damaged layer 15 in the semiconductor substrate 1 made of p-type germanium doped with boron (B) in the embodiment of the present invention. Fig. 14 is a conceptual diagram showing a state in which the damaged layer 15 existing on the surface of the semiconductor substrate 1 is removed in the embodiment of the present invention. In Fig. 13 and Fig. 14, a p-type single crystal germanium substrate, i.e., a semiconductor substrate 1, which is cut by a wire saw with a wire saw is shown. When a p-type single crystal germanium substrate is formed, a cylindrical ingot is produced by, for example, a pull-up method. Boron is doped in a crucible which is melted, for example, at 1400 ° C, and a hole is formed in the crucible, and is pulled up by a pull-up method, thereby obtaining a cylindrical p-type twin ingot.

In general, in the doping of boron, there is a low resistance in the ingot, and on the other hand, the purity of the crucible is lowered, that is, the electrons taken out are reduced, and the crystal quality is lowered. Therefore, it is necessary to pay attention to the doping amount of boron. . The reduction in purity as shown above, especially in the case of a single crystal yttrium of stable quality, is well known and is generally managed by the specific resistance of ruthenium. In addition, it is necessary to pay attention to the fact that impurities such as tungsten, titanium, iron, aluminum, and nickel are formed in the crucible to form a level in the central portion of the crystal defect and the band gap of the crucible, and accelerate in the interior of the crucible substrate of the solar cell unit 10. The recombination of the generated carriers reduces the current drawn.

The cylindrical p-type twin ingot is cut into a block of the ingot size by a band saw, and further processed into a semiconductor substrate 1 for a practical size solar cell by a multi-wire saw. The damaged layer 15 which is formed by machining is left on the surface of the semiconductor substrate 1 which is sliced by the multi-wire saw, and the solar battery cell 10 having high photoelectric conversion efficiency cannot be produced as it is. Therefore, the damage layer 15 is removed by etching using an aqueous solution of caustic alkali represented by sodium hydroxide or potassium hydroxide or by etching an acid solution such as a mixed solution of hydrofluoric acid and nitric acid at room temperature. The damage layer 15 also varies depending on the slicing method of the p-type germanium substrate, and generally remains to a depth of about 10 μm. Next, the etching treatment time must be made variable depending on the degree of remaining of the damaged layer 15.

Fig. 15 is a schematic cross-sectional view showing a texture etching process for forming a texture structure on the surface of the semiconductor substrate 1 in the embodiment of the present invention. After the damage layer 15 is removed, the semiconductor substrate 1 is etched in step S10, and as shown in Fig. 15, a micro unevenness 2 having a size of about 1 μm to 10 μm in depth is formed on the surface of the semiconductor substrate 1 as a texture. structure. The etching for forming the texture structure is generally treated by a mixed solution method in which an alkali aqueous solution such as an aqueous sodium hydroxide solution is mixed with isopropyl alcohol (Isopropyl Alcohol: IPA), but a dry etching method may be selected.

As shown in Fig. 14, in the semiconductor substrate 1 on which the damage layer 15 has been removed, the amount of light taken into the semiconductor substrate 1 is reduced before and after the light incident on the surface is reflected by 35%. By forming the texture structure on the light-receiving surface side of the semiconductor substrate 1, the light is diffused and reflected on the surface of the fine unevenness 2, and multiple reflection of light is generated on the surface of the solar cell unit 10, whereby the reflectance can be effectively reduced. Then, by increasing the amount of light taken into the semiconductor substrate 1, the current value taken out by the solar cell unit 10 can be increased, and the photoelectric conversion efficiency can be improved.

Fig. 16 is a schematic cross-sectional view showing an impurity diffusion step of forming the n-type impurity diffusion layer 3 on the semiconductor substrate 1 in the embodiment of the present invention. After the texture structure is formed, in step S20, a PN junction which is a basic structure of the solar cell is formed. The PN junction is used to form a textured structure of the semiconductor substrate 1 on the surface, so that phosphorus (P) is diffused from the surface by thermal diffusion, as shown in Fig. 16, by using a sheet resistance of 60 Ω/sq. to 200 Ω/sq. The left and right n-type impurity diffusion layers 3 are formed on the surface layer of the semiconductor substrate 1. The vapor phase diffusion of phosphorus to the semiconductor substrate 1 is generally carried out in a phosphorus oxychloride (POCl ₃ ) gas atmosphere.

Here, as shown in Fig. 16, a surface of the semiconductor substrate 1 after the transient formation of the n-type impurity diffusion layer 3 is formed with a film containing glass as a main component and a phosphorus glass layer 3a containing P ₂ O ₅ and SiO ₂ . Therefore, it is removed using a treatment liquid represented by hydrofluoric acid. By removing the phosphor glass layer 3a, the light permeability is improved, and recombination of the carrier occurring in the solar cell unit 10 can be prevented.

In the general phosphorus diffusion step, in order to stabilize the diffusion concentration of phosphorus to the semiconductor substrate, the diffusion layer of the surface of the substrate is often etched after diffusion of phosphorus, and then the temperature is further increased at a high temperature. The diffusion process is also a method of driving in.

Fig. 17 is a schematic cross-sectional view showing a planarization process on the back side of the semiconductor substrate 1 in the embodiment of the present invention. After the formation of the PN junction, in step S30, a planarization step of removing the n-type impurity diffusion layer 3 formed on the back surface side of the semiconductor substrate 1 and planarizing the back surface side of the semiconductor substrate 1 is performed. Thereby, the semiconductor substrate 11 in which the n-type impurity diffusion layer 3 is formed on the light-receiving surface side and the back surface is formed flat is obtained.

First, after protecting the light-receiving surface side with a protective film such as a resist or an acid-resistant resin, the semiconductor substrate 1 is immersed in a fluoro-nitric acid solution, whereby the end surface of the semiconductor substrate 1 and the n-type impurity diffusion layer 3 on the back surface side are removed. Then, the back surface of the semiconductor substrate 1 is etched by a mixed acid or aqueous alkali solution of a hydrogen fluoride aqueous solution and nitric acid in a state where the light-receiving surface side is protected, whereby the back surface of the semiconductor substrate 1 is formed flat. The flattening treatment of the back surface of the semiconductor substrate 1 is for the process required for the stabilization of the PERC structure.

However, the n-type impurity diffusion layer 3 may not be formed in advance on the back surface side of the semiconductor substrate 1.

Fig. 18 is a schematic cross-sectional view showing a step of forming the back passivation film 5 and the cap film 6 on the back surface of the semiconductor substrate 1 in the embodiment of the present invention. Here, a case where the cover film 6 is additionally formed on the back passivation film 5 will be described. After the back surface of the semiconductor substrate 1 is planarized, in step S40, as shown in FIG. 18, the back surface passivation film 5 made of alumina (Al ₂ O ₃ ) having a film thickness of about 5 nm to 20 nm and the film thickness are formed. A cover film 6 made of a hafnium oxynitride film (SiON) of about 100 nm to 150 nm is formed on the back surface of the semiconductor substrate 1 in this order. For the formation of the back passivation film 5 and the cap film 6, for example, a plasma CVD method can be used.

By forming the back surface passivation film 5, the carrier disappearance at the interface between the surface of the back surface of the semiconductor substrate 1 and the back surface passivation film 5 is suppressed, and red light having a long wavelength is reflected on the back surface passivation film 5 to return to the semiconductor substrate 1 Therefore, the effect of improving the photoelectric conversion efficiency can be expected.

Fig. 19 is a schematic cross-sectional view showing a step of forming the anti-reflection film 4 on the light-receiving surface side of the semiconductor substrate 11 in the embodiment of the present invention. After the back passivation film 5 and the cap film 6 are formed, in step S50, as shown in Fig. 19, the anti-reflection film 4 made of a SiN film having a film thickness of 65 nm to 90 nm is formed on the n-type impurity diffusion layer. The light-receiving surface side of the semiconductor substrate 1 of 3 is also the n-type impurity diffusion layer 3. In other words, in order to effectively block and take in light in the semiconductor substrate 11, a film having a different refractive index is formed on the light incident surface of the semiconductor substrate 11 in addition to the above-described texture structure. In the formation of the anti-reflection film 4, for example, a chemical vapor deposition (CVD) method is used, and a mixed gas of decane and ammonia and oxygen is used to form a tantalum nitride film as the anti-reflection film 4. Among them, a niobate film may be formed as the anti-reflection film 4.

By using the plasma CVD method in the formation of the anti-reflection film 4, it is possible to eliminate the presence of hydrogen ions and radicals generated in the formation process of the anti-reflection film 4 on the surface of the semiconductor substrate 11 while forming the anti-reflection film 4. And the dangling bond of the crystal grain boundary to obtain a crystal crystal lifting effect. The dangling means a state in which the bonding of the ruthenium atoms existing on the surface of the substrate is cut off, and by the bonding with the hydrogen ions and the radicals, the quasi-displacement to the end of the band gap can reduce the recombination speed.

With respect to the anti-reflection film 4, by using interference of light reflected on the surface of the anti-reflection film 4 and the surface of the semiconductor substrate 11, the periods of the two are shifted by a half wavelength, thereby canceling each other out, and the reflected light is not detected. The status can be described as appropriate. However, when the solar cell module is treated as a product, it is necessary to also process members such as a cover glass and a sealing material which will be described later, and it is necessary to pay attention to the specifications of the appropriate anti-reflection film 4 described above.

Fig. 20 is a schematic cross-sectional view showing a step of forming a contact hole 7 on the back side of the semiconductor substrate 1 in the embodiment of the present invention. By forming the back surface passivation film 5 and the cap film 6 on the back surface of the semiconductor substrate 1, the back surface of the semiconductor substrate 1 has an insulating structure. Therefore, in step S60, in order to electrically connect the back surface of the semiconductor substrate 1 and the back surface electrode 13, it is necessary to provide the contact hole 7.

First, a dot contact hole 6H having a predetermined contact hole diameter penetrating through the cover film 6 in the film thickness direction, and a dot contact hole 5H having a predetermined contact hole diameter penetrating through the back surface passivation film 5 in the film thickness direction are formed on the semiconductor substrate 1 The back side is integrated with the area other than the tab wire connection region 14. The contact hole 6H and the contact hole 5H are formed in a lattice shape having a predetermined interval using, for example, a laser. However, when only the back surface passivation film 5 is formed without forming the cover film 6, only the contact hole 5H is formed.

Next, the contact hole 1H having the predetermined contact hole diameter and the predetermined contact hole depth similar to the contact hole 5H is formed in a region corresponding to the lower portion of the contact hole 5H on the back surface of the semiconductor substrate 1 by using a laser. Thereby, on the back surface side of the semiconductor substrate 1, a contact hole 7 having a predetermined contact hole diameter and a predetermined contact hole depth which communicates with the contact hole 5H and the contact hole 5H is formed.

Fig. 21 is a schematic plan view showing a region where the contact hole 7 is formed in the back side of the semiconductor substrate 1 in the embodiment of the present invention. The contact hole 7 is disposed in a region other than the tab wire connecting region 14 in the back surface of the semiconductor substrate 1 in a dot shape as described above without any omission. The contact holes 7 are arranged at equal intervals on the back surface of the semiconductor substrate 1 at intervals of about 0.5 mm to 1 mm. In Fig. 21, the mode shows the interval and number of adjacent contact holes 7.

Here, the formation of the contact hole is generally performed by laser irradiation, but when the back electrode 13 is formed, the hole processing can be replaced by using an electrode material having a burn-through property.

Fig. 22 is a schematic cross-sectional view showing a step of printing an electrode material paste for forming the light-receiving surface electrode 12 and the back surface electrode 13 on the front and back surfaces of the semiconductor substrate 11 in the embodiment of the present invention. In step S70, the electrode material of the back surface bonding electrode 13b is a back bonding electrode material paste 16a containing silver and glass, and as shown in Fig. 22, the pattern of the back surface bonding electrode 13b is formed by a screen printing method. The cover film 6 in the back surface of the semiconductor substrate 11 is selectively printed. The back surface bonding electrode material paste 16a is formed on the cover film 6, and is printed in a lattice shape having a predetermined interval in a predetermined formation region of the tab line connection region 14 in which the contact hole 7 is not formed. If the cover film 6 is not formed, the back surface bonding electrode material paste 16a is printed on the back surface passivation film 5.

Thereafter, the back surface bonding electrode material paste 16a is dried. In the screen printing system, a general screen printing machine is used. In other words, the squeegee is scanned on the printing mask in a state in which the electrode material paste is placed, and the electrode material paste is printed on the printing surface of the semiconductor substrate 11 through the printing mask.

Next, in step S80, the back surface current collecting electrode material paste 16b including the aluminum and glass is used as the electrode material of the back surface collecting electrode 13a, and the back surface is collected by the screen printing method as shown in FIG. The pattern of the electrode 13a is selectively printed on the back surface of the semiconductor substrate 11. The back collector electrode material paste 16b is an electrode material paste containing a diffusion source of a first conductivity type. The back surface collector electrode material paste 16b is placed on the back surface side of the semiconductor substrate 11, and the contact hole 7 is filled and printed on the entire cover film 6 in the in-plane direction of the back surface of the semiconductor substrate 11. That is, the back collector electrode material paste 16b is printed by connecting the adjacent contact holes 7 therebetween. The back collector electrode material paste 16b is printed while surrounding the back surface bonding electrode material paste 16a. Thereafter, the back collector electrode material paste 16b is dried.

Next, in step S90, as shown in FIG. 22, the electrode material of the light-receiving surface electrode 12 is a light-receiving surface electrode material paste containing silver and glass on the anti-reflection film 4 on the light-receiving surface side of the semiconductor substrate 11. 16c is selectively printed into the shape of the light-receiving surface electrode 12 by screen printing. In other words, the light-receiving surface electrode material paste 16c is selectively printed as a pattern of the light-receiving surface gate electrode 12G and a pattern of the light-receiving surface bus bar electrode 12B.

Fig. 23 is a schematic cross-sectional view showing a step of simultaneously baking the electrode material paste to form the light-receiving surface electrode 12 and the back surface electrode 13 in the embodiment of the present invention. Next, in step S100, the back surface bonding electrode material paste 16a and the back surface collector electrode material paste are applied in the atmosphere or in an oxygen gas atmosphere, for example, at a temperature of 700 ° C to 900 ° C for 2 seconds to 10 seconds. The printed pattern of the material 16b and the light-receiving surface electrode material paste 16c is simultaneously fired. By baking, the organic solvent or the like contained in the electrode material paste is thermally decomposed, and the electrode is deteriorated into a preferable low-resistance state, and ohmic contact is ensured between the electrode and the semiconductor substrate 11.

In other words, as shown in Fig. 23, the light-receiving surface electrode material paste 16c is burned through the anti-reflection film 4, and the light-receiving surface electrode 12 that is electrically connected to the 11-type impurity diffusion layer 3 is formed.

Further, as shown in Fig. 23, the back surface collector electrode 13a and the back surface bonding electrode 13b are formed, and in the surface layer of the back surface of the semiconductor substrate 11 which is in contact with the back surface collecting electrode 13a, aluminum is formed by the back surface collecting electrode. The p+ region of the 13a high concentration diffusion is also the BSF layer 8, and the BSF layer 8 and the back collector electrode 13a are electrically connected in the contact hole 7. That is, the back collector electrode material paste 16b printed in the contact hole 7 and the back surface of the semiconductor substrate 11 are eutectic to form the BSF layer 8, and a point contact electrically connected to the BSF layer 8 is formed. .

In the light-receiving surface electrode 12, it is necessary to ensure good electrical contact with the n-type impurity diffusion layer 3 existing under the anti-reflection film 4 through the anti-reflection film 4m as an insulating film, and thus at least the light-receiving surface gate electrode 12G In the electrode material paste, the glass material is mixed. Then, when the electrode material paste is melted, the glass material is eutectic with the tantalum nitride film or titanium oxide as the anti-reflection film 4, and contains silver as a metal component to reach the n-type impurity diffusion layer 3 .

However, if the silver as the metal component does not reach the n-type impurity diffusion layer 3, the characteristic of the curve factor (Fill Factor: FF) of the solar battery cell 10 is lowered, and if the silver as the metal component reaches the deeper than the n-type impurity diffusion layer 3 At the time of the position, the solar battery unit 10 leaks when generating electricity, so care must be taken.

Further, when the cast substrate is exposed to a high temperature, the diffusion length of the carrier is small, and thus the crystallinity is deteriorated. Therefore, it is preferred that the electrode is fired as much as possible at a low temperature for a short period of time.

Further, in the above-described PERC construction unit, there is a case in which light inducing degradation (LID) caused by light irradiation causes a problem. It is known that electrons or holes move in a silicon bulk, and the pair of boron (B) and oxygen (O) become unstable, compared with a solar cell having a BSF structure on the back side. Significantly degraded.

It is also known that photo-induced attenuation is more pronounced especially in low specific resistance substrates depending on the amount of boron (B) doping. A technique for annealing a pair of boron (B) and O (oxygen) at a high temperature of about 100 ° C to 250 ° C while irradiating light in order to suppress the photo-induced attenuation is low. In the specific resistance P-type PERC construction unit, it is preferred to carry out the aforementioned treatment.

The solar cell unit 10 is obtained by performing the above steps. Among them, the printing of the electrode material paste can be carried out by other methods such as sputtering or transfer.

(connection of connector wires)

Next, the tab wire 20 is connected to the solar cell unit 10. In other words, a region on one end side of the tab wire 20 is formed on the back surface bonding electrode 13b formed on the back surface 10B of the solar battery cell, and is disposed on the light receiving surface bus bar electrode 12B formed on the light receiving surface 10A of the adjacent solar battery cell. The area on the other end side of the tab line 20. Next, the solder material coated on the tab wire 20 is melted by heating, and then solidified by cooling. Thereby, the region on one end side of the tab wire 20, the region on the other end side of the back surface bonding electrode 13b and the tab wire 20, and the solder material of the light-receiving surface bus bar electrode 12B are bonded to each other, and the solar cell unit 10 is electrically and The connector wire 20 is mechanically connected.

Fig. 24 is a schematic view showing a bonding wire bonding step of electrically connecting the light-receiving surface electrode 12 and the back surface electrode 13 and the tab wire 20 in the embodiment of the present invention. As shown in Fig. 24, in the region where one end side of the tab wire 20 is overlapped on the back surface bonding electrode 13b of the solar cell unit 10, the other end side of the tab line 20 is overlapped on the light-receiving surface bus bar electrode 12B (not shown). In the state in which the bonding wire 20 is heated by the heating tool 200, electrical bonding and mechanical bonding of the tab wire 20 and the back bonding electrode 13b, and electrical bonding of the tab wire 20 and the light-receiving surface bus bar electrode 12B are simultaneously obtained. And mechanical joints. Here, the bonding of the solar cell unit 10 and the tab wire 20 may be performed by using a conductive paste or an adhesive conductive film (CF).

As shown in Fig. 24, when the tab wire 20 is connected to the solar cell unit 10, thermal stress is applied to the solar cell unit 10, and the periphery of the tab wire 20, that is, the light receiving surface busbar, is cooled via cooling in a gaseous environment. Residual thermal stress occurs in the periphery of the electrode 12B and the periphery of the back surface bonding electrode 13b.

However, in the solar battery cell 10 of the present embodiment, as described above, the contact hole 7 is formed in a region other than the tab wire connection region 14 in the back surface of the semiconductor substrate 11. Thereby, the manufacturing yield of the solar cell unit 10 due to the influence of the residual thermal stress on the connection of the tab wire 20 of the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b of the solar battery cell 10 as described above can be suppressed. The deterioration and the output of the solar cell module 100 are lowered.

Fig. 25 is a perspective view showing the solar battery array 50 in the embodiment of the present invention. In response to the connection process of the above-described patch wires 20, as shown in Fig. 25, a plurality of solar cell arrays 50 of a desired number of solar battery cells 10 are connected in series. Next, the plurality of solar battery arrays 50 obtained as described above are connected by the transverse joint wires 25 to form the solar cell array 70. The solar battery array 70 is formed by connecting a plurality of solar battery arrays 50 arranged in parallel, using a bus bar as a horizontal joint wire 25 in series, and providing a bus bar as an output terminal wire 26 for electric power extraction.

In the manufacturing process of the solar cell array 50, thermal stress is also applied to the solar cell unit 10, and there is a possibility that a crack originating from the contact hole 1H occurs in the semiconductor substrate 1.

However, in the solar battery cell 10 of the present embodiment, as described above, the contact hole 7 is formed in a region other than the tab wire connection region 14 in the back surface of the semiconductor substrate 1. Thereby, the manufacturing yield of the solar cell unit 10 due to the influence of the residual thermal stress on the connection of the tab wire 20 of the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b of the solar battery cell 10 as described above can be suppressed. The deterioration and the output of the solar cell module 100 are lowered.

(formation of laminated body)

Next, in the arrangement shown in FIG. 2, the light-receiving surface side sealing material 33 and the light-receiving surface protective material 31 are disposed on the light-receiving surface side of the solar cell array 70, and the back side sealing material 34 and the back surface are disposed on the back side of the solar cell array 70. The protective material 32 forms a laminate.

(Cascade processing)

Next, the laminated body is mounted in a laminating apparatus, and heat treatment and lamination processing are performed for 30 minutes or more at 140 ° C or more and 160 ° C or less. Thereby, each member of the laminated body is integrated by the light-receiving surface side sealing material 33 and the back surface side sealing material 34, and the solar cell module 100 is obtained.

The solar cell module 100 is installed outside the house, and there are many cases in which external forces such as snow load or wind are applied to the surface cover glass and the back film. At this time, stress is also generated in the encapsulated internal solar cell unit 10. Therefore, cracks originating from the contact hole 1H occur in the semiconductor substrate 1, and there is a risk that power generation is lowered.

However, in the solar battery cell 10 of the present embodiment, as described above, the contact hole 7 is formed in a region other than the tab wire connection region 14 in the back surface of the semiconductor substrate 1. Thereby, the manufacturing yield of the solar cell unit 10 due to the influence of the residual thermal stress on the connection of the tab wire 20 of the light-receiving surface bus bar electrode 12B and the back surface bonding electrode 13b of the solar battery cell 10 as described above can be suppressed. The deterioration and the output of the solar cell module 100 are lowered.

As described above, in the solar battery cell 10 of the present embodiment, the contact hole 7 provided on the back side is selectively formed in a region other than the tab wire connecting region 14 in the back surface of the semiconductor substrate 1. Therefore, as described above, the passivation effect in the back surface of the semiconductor substrate 11 due to the back surface passivation film 5 is improved, and the characteristics of the solar cell unit 10 are improved, and the light-receiving surface electrode 12 of the solar cell unit 10 can be suppressed. The occurrence of a problem arises by the connection of the tab wire 20 of the back electrode 13.

The configuration shown in the above embodiments is an example of the present invention, and a part of the configuration may be omitted or changed without departing from the spirit and scope of the invention.

Claims (8)

 A solar cell unit comprising: a first conductivity type germanium substrate; a back surface passivation film formed on a back surface of the germanium substrate facing the light receiving surface; and a plurality of contact holes penetrating through the back surface passivation film and being passivated by the back surface The surface of the film reaches the surface layer of the back surface of the ruthenium substrate; and the plurality of first back electrodes are arranged on the back surface passivation film along the first direction for connecting the strip-shaped tab lines along the first direction; In the second back surface electrode, the germanium substrate in the contact hole is connected to the first back surface electrode, and the contact hole is provided in a region adjacent to the first back surface electrode in the first direction.    The solar battery unit according to claim 1, wherein the contact hole is provided in a surface of the back surface to avoid a region where the joint wire is connected.    The solar battery unit according to claim 2, wherein the first back surface electrode has a square shape having a pair of sides along the first direction in a surface of the back surface, and the width of the tab line is set to In the case of W, the contact hole is provided in a second direction orthogonal to the first direction in the surface of the back surface, and is provided in a range away from the pair of sides by a distance of W/2.    The solar battery cell according to claim 3, wherein the width of the first back surface electrode in the second direction is 2 W, and the contact hole is away from a center position of the first back surface electrode in the second direction It is set for the range of the distance of W.    A solar battery module comprising: a first solar battery unit; a second solar battery unit arranged in the first solar battery unit; and a strip-shaped joint wire disposed in the first solar battery unit The light-receiving surface electrode on the light-receiving surface side is connected to the first back surface electrode provided on the back surface of the second solar cell unit facing the light-receiving surface, and the first solar cell unit and the second solar cell unit are: a conductive type germanium substrate; a back passivation film formed on a back surface of the germanium substrate; a plurality of contact holes penetrating through the back surface passivation film, and a surface of the back surface passivation film reaching a surface layer of the back surface of the germanium substrate; a back electrode disposed on the back passivation film along a first direction; and a second back electrode connecting the germanium substrate in the contact hole to the first back electrode to avoid the first direction and The contact hole is provided in a region adjacent to the first back surface electrode.    The solar cell module of claim 5, wherein the contact hole is not provided in a region of the back surface in which the connection line is connected.    The solar battery module according to claim 6, wherein the first back surface electrode has a square shape having a pair of sides along the first direction in a surface of the back surface, and the width of the tab line is set. In the case of W, the contact hole is provided in a second direction orthogonal to the first direction in the plane of the back surface, and is provided in a range away from the pair of sides by a distance of W/2.    The solar cell module according to claim 7, wherein the width of the first back surface electrode in the second direction is 2 W, and the contact hole is away from the center of the first back surface electrode in the second direction. The position is set to the range of the distance of W.