JPH0766979B2 - Method for manufacturing corrugated solar cell - Google Patents

Description

The present invention relates to a method for manufacturing a solar cell using a corrugated substrate.

[Conventional technology]

Conventionally, when a corrugated solar cell is manufactured by forming an impurity layer of a type different from that of the substrate or an impurity layer of a different concentration on the front surface or the back surface of the substrate, first, a V-shaped groove is formed on the front surface and the back surface of the wafer. After forming a corrugated type substrate, an impurity layer of a type different from that of the substrate or an impurity layer of a different concentration is formed on the front surface or the back surface of the substrate to manufacture a corrugated solar cell.

Prior art relating to this is, for example, IEE, Transaction on Electron Devices, Vol. 37, No. 2, (1990), pages 344 to 3.
Page 47 (IEEE, TRANSACTIONS ON ELECTRON DEVICES, VOL.3
7, NO.2, (1990) pp.344-347],
A corrugated silicon solar cell has been proposed in which a corrugated substrate is formed and then a p + layer is formed on a convex portion on the back surface of the corrugated substrate.

[Problems to be Solved by the Invention]

As described above, in the prior art, when manufacturing a corrugated solar cell, after forming a corrugated substrate, an impurity layer of a different type (for example, p + layer) or an impurity layer of a different concentration from the substrate is formed. In the case of selectively forming the impurity layer only on the convex portion on the front surface or the back surface of the corrugated substrate, a complicated process of using a mask so that the impurity layer is not formed on other portions is required. There was a problem I needed.

An object of the present invention is to solve the problems in the above-mentioned conventional techniques, and in the case of producing a corrugated solar cell, in a step before forming the corrugated substrate, a predetermined portion of the front surface or the back surface of the wafer is formed. It is an object of the present invention to provide a method for manufacturing a corrugated solar cell by a very simplified process by forming a necessary impurity layer and then forming a V-shaped groove.

[Means for Solving the Problems]

In order to achieve the above-mentioned object of the present invention, before forming a V-shaped groove in a wafer to produce a corrugated substrate, an impurity layer (for example, p + layer) required in advance is formed in a set portion of the wafer surface. After that, by forming a V-shaped groove for forming a corrugated substrate, the manufacturing process of the corrugated solar cell can be further simplified.

[Action]

The reason why the manufacturing process of the corrugated solar cell of the present invention can be simplified will be described with reference to the drawings.

In a conventional corrugated solar cell, when an impurity layer of a type different from that of the substrate or an impurity layer of a different concentration is formed on the front surface or the back surface of the corrugated substrate, for example, as shown in FIG. A V-shaped groove for forming the corrugated substrate 5 is formed on the back surface 4, and then, on the front surface or the back surface of the corrugated substrate 5, impurity layers 6 and 7 of a different type from the corrugated substrate 5 and different concentrations are formed. Impurity layer
It was forming 6,7. On the other hand, in the present invention, as shown in FIG. 1, for example, on the front surface 1 or the back surface 4 of the wafer, the impurity layers 6 and 7 of different types from the corrugated substrate 5 and the impurity layers 6 and 7 of different concentrations are formed. Is formed to the depth of the impurity diffusion surface 2 on the front surface or the impurity diffusion surface 3 on the back surface shown by the broken line in the figure, and then a V-shaped groove is formed on the wafer front surface 1 and the wafer back surface 4 to form a corrugated type. Impurity layers 6 and 7 different from the other portions can be formed only on the convex portions on the front surface or the rear surface of the substrate 5. Conventionally, when the impurity layers 6 and 7 different from the other portions are formed only on the convex portions of the corrugated substrate 5, after the corrugated substrate 5 is formed, it is selectively formed using some mask.
However, in the method of the present invention, a complicated mask forming step can be omitted in the step of forming the impurity layers 6 and 7. In addition, the mask and corrugated substrate 5
Since it is not necessary to align the position with the convex portion of, it is possible to perform highly accurate processing with the self line.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 2 to 4.

As the wafer, p-type single crystal Si having a (100) surface was used, and phosphorus was diffused on the surface 1 of the wafer by a normal thermal diffusion method as shown in FIG. 2 to form an n + layer 6n. On the back surface 4 of the wafer, boron was diffused by a normal thermal diffusion method to form a p + layer 7p. Next, an oxide film 8 was formed on the front surface 1 of the wafer and the back surface 4 of the wafer, and anisotropic etching was performed with an alkaline solution using the oxide film 8 as an etching mask to form a V-shaped groove, thereby forming a corrugated substrate 5. As a result, the n + layer 6n and the p + layer are formed on the convex portion of the corrugated substrate 5.
7p could be formed easily and accurately without any special process. Then, as shown in FIG.
An n + layer 9n having an impurity concentration different from that of the convex n + layer 6n on the surface of the corrugated substrate 5 is provided on the slope of the V-shaped groove on the surface.
The p + layer 10p having an impurity concentration different from that of the p + layer 7p of the convex portion on the back surface of the corrugated substrate 5 is provided on the slope of the V-shaped groove on the back surface.
Were respectively formed. Further, as shown in FIG. 4, a surface passivation film 11 made of an oxide film is formed on the surface.
Then, the antireflection film 13 was formed, and the surface electrode 15 having ohmic contact with the n + layer 6n was formed through the contact holes formed in these films. A back surface passivation film 12 made of an oxide film and a back surface reflecting mirror 14 were formed on the back surface, and a back surface electrode 16 having ohmic contact with the p + layer 7p was formed through a contact hole formed in these films.

In the above embodiments, the case of using a single crystal Si wafer has been described as an example, but this is a single crystal wafer using a semiconductor material such as GaAs, InP, or Ge, or another compound semiconductor material. Is also good. In addition, isotropic etching and machining,
When forming the corrugated substrate of the present invention by laser processing or the like, not only a single crystal but also a polycrystalline or amorphous material can be used.

Further, the front surface and back surface passivation films 11 and 12 and the antireflection film 13 described with reference to FIG. 4 may be formed by using other materials or may be omitted, or the front surface electrode 15 and the back surface electrode 16 may not be formed. Needless to say, the effect of the present invention can be obtained even when the formation position and shape are different.

As described above, in the embodiments of the present invention, as a method of forming an impurity layer of a type different from that of the corrugated substrate or an impurity layer having a different concentration, which is formed on the convex portion of the corrugated substrate or the slope of the V-shaped groove,
Although the method of diffusing the impurities has been described, this is the same as the present invention even if it is formed by depositing an impurity layer of a type different from that of the corrugated substrate or an impurity layer of a different concentration on the surface of the corrugated substrate or the wafer. It has the effect of.

〔The invention's effect〕

When a thin solar cell is formed using a corrugated substrate, the corrugated substrate is formed by forming an impurity layer of a different type or a different concentration from the substrate on the convex portion of the corrugated substrate by the method of the present invention. It is possible to obtain a corrugated solar cell that is much simpler and has higher performance than the conventional process of forming the impurity layer using a mask after forming the substrate.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of the corrugated solar cell of the present invention, and FIGS. 2 to 4 are schematic diagrams showing an example of the configuration of the corrugated solar cell exemplified in the examples of the present invention. FIG. 5 is a schematic view showing an example of the configuration of a conventional corrugated solar cell. DESCRIPTION OF SYMBOLS 1 ... Wafer surface, 2 ... Front surface impurity diffusion surface 3 ... Back surface impurity diffusion surface 4 ... Wafer back surface 5 ... Corrugated substrate 6 ... Impurity layer, 6n ... n + layer 7 ... Impurity layer, 7p ... p + layer 8 ... Oxidation Film etching mask 9n ... n + layer, 10p ... p + layer 11 ... Front surface passivation film 12 ... Back surface passivation film 13 ... Antireflection film, 14 ... Back surface reflecting mirror 15 ... Front surface electrode, 16 ... Back surface electrode

Claims (2)

[Claims] 1. A corrugated substrate having a V-shaped groove on the front and back surfaces of a wafer, and a convex portion on one of the front and back surfaces of the corrugated substrate having a first impurity layer of a different type from the corrugated substrate,
The other convex portion has a second concentration different from that of the corrugated substrate.
Third impurity layer having the same conductivity type as that of the first impurity layer on the slope of the V-shaped groove in which the first impurity layer exists.
Corrugated solar cell using the corrugated substrate having the impurity layer of 4 and a fourth impurity layer of the same conductivity type as the second impurity layer on the slope of the V-shaped groove in which the second impurity layer exists. In the method for manufacturing a battery, a first layer containing impurities of the first impurity layer and a second layer containing impurities of the second impurity layer are formed on a predetermined surface of the wafer before forming the V-shaped groove. And a part of the first layer or the second layer on the front surface or the back surface of the wafer where the V-shaped groove exists is removed by the step of forming the V-shaped groove, After the step of forming the first and second impurity layers on the convex portion and the step of forming the first and second impurity layers, the third impurity layer and the fourth impurity layer are formed on the slope of the V-shaped groove. Corrugated type characterized by including a step of forming a layer Method of manufacturing a solar cell. 2. The method for manufacturing a corrugated solar cell according to claim 1, wherein the V-shaped groove is formed simultaneously on the front surface and the back surface of the wafer.