JPH03225876A - Structure of board for corrugated solar battery - Google Patents

Abstract

PURPOSE:To elevate strength while thinning a board by making a trench, not substantially parallel with a straight line, exist on the straight line optionally crossing the main surface of a board. CONSTITUTION:The main surface of a board is divided in two kinds, large and small, of squares. For the larger squares out of them, for example, regions 1 to 3 are made the regions which have V grooves parallel with the X axis, and the regions 11 and 12 are made the regions which have V grooves parallel with the Y axis. For this reason, a region, which has V grooves 20 parallel with the X axis, surely exists on any straight line which crosses, in parallel with the Y axis, for example the main surface of the board, and also a region, which has V grooves parallel with the Y axis, surely exists even on any straight line, which crosses it in parallel with the X axis. Hereby, even in case that the stress is added in the direction parallel with the X-axis or the Y-axis to the main surface of the board, the mechanical strength of the board can be maintained enough large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the structure of a solar cell substrate using a corrugated substrate.

[Conventional technology]

Conventionally, rThe Conference Record
d of the 20th IEEE Photovo
taic 5specialistsconferen
CE 1988 pp, 792-795J, since the grooves formed on the main surface of the substrate were oriented in the same direction, a cross beam was provided at right angles thereto to increase mechanical strength.

[Problem to be solved by the invention]

As mentioned above, conventionally, the strength of the element was increased by adding a cross beam, but since it is not possible to increase the area of the cross beam in order to improve the element characteristics, sufficient mechanical strength is required. was difficult to obtain.

An object of the present invention is to provide a corrugated solar cell substrate that can increase mechanical strength without deteriorating device characteristics.

[Means to solve the problem]

In order to achieve the above object, the present invention has a structure in which at least some of the directions of the plurality of V grooves formed on the main surface of the substrate are different from the others.

[Effect]

The above means will be explained using the drawings.

As shown in Fig. 2, conventional substrates for corrugated solar cells maintain mechanical strength against stress applied in the direction A-A' in the figure by providing a cross beam 100 orthogonal to the groove 20. . In order to increase the strength using this structure, it is necessary to increase the area of the cross beam 100. However, as can be seen from the BB' cross-sectional view, the substrate thickness at the cross beam portion is larger than other portions, so if this area increases, it becomes impossible to keep the average thickness of the substrate thin.

In order to solve the above-mentioned problem, the region having the grooves was divided into smaller parts, and the arrangement of the regions was made into a structure as shown in FIG. 1, for example. In this structure, the main surface of the substrate is divided into two squares, large and small. Among the larger squares, for example, regions 1 and 2.3 in the figure are regions having V-grooves parallel to the X-axis, and regions 11.12 are regions having ■-grooves parallel to the Y-axis. As a result, for example, on any straight line that crosses the main surface of the substrate parallel to the Y-axis, there is always a region having a V-groove parallel to the X-axis. Further, even in a straight line that crosses parallel to the X-axis, there is always a region having a V-groove parallel to the Y-axis.

As a result, even when stress is applied to the main surface of the substrate in a direction parallel to the X-axis or the Y-axis, the mechanical strength of the substrate can be maintained sufficiently high.

Although the above description describes the minimally repeated pattern in each area, it goes without saying that this pattern must cover the main portion of the substrate. The same thing can be said if regions 2, 11 and 3, 12 in the same figure are regions having V grooves parallel to the X axis and the Y axis, respectively. Further, the small square portion may be divided into regions having V grooves parallel to the X or Y axis according to any rule. Furthermore, the V-grooves parallel to the X-axis and Y-axis in the above description may be oriented in an oblique direction like the Y'-axis in the figure.

The most important thing here is that on any straight line that crosses the main surface of the substrate, there are at least two regions having V-grooves that are not substantially parallel to the straight line.

Application examples of the present invention are shown below.

Figure 3 shows an example using rectangles and squares. In this example, for example, areas 1, 2, 3, 4.5 and areas 11, 12, 1
The above objective can be achieved by forming 3.14 into regions having grooves in different directions.

FIG. 4 shows an example using an L-shape. In this example, for example, areas 1, 2.3... and areas 11°12.13...
The above objective can be achieved by forming regions having V grooves in different directions.

FIG. 5 shows an example using only rectangles. In this example,
For example, area 1, 2.3... and area 11゜1.2.13
The above objective can be achieved by making ... into regions having ■grooves in different directions.

FIG. 6 shows an example using a T-shape. In this example, the above object can be achieved by, for example, making regions 1, 2, 3, . . . and regions 11, 12, . . . regions having grooves in different directions.

FIG. 7 shows an example using a cross shape. In this example, the above objective can be achieved by, for example, making regions 1, 2, . . . and regions 11, 12, . . . regions having V-grooves in different directions.

FIG. 8 shows an example using a key type. In this example, the above objective can be achieved by, for example, making regions 1, 2, . . . and regions 11, 12, . . . regions having V-grooves in different directions.

Next, another example will be shown using FIG. In this example, main region 1 of the substrate has a V-groove parallel to the Y-axis, and region 2 has a V-groove parallel to the X-axis. It is clear that the above object can also be achieved with such a structure.

FIG. 10 shows an application of the example explained in FIG. 9.

In this example, the shape of area 2 in Figure 9 is area 2.3 in this figure.
．． It has been replaced with a shape similar to 4.

We have explained various examples so far, but what combinations can be considered as long as it satisfies the existence of at least one region on a straight line that crosses the main surface of the substrate that has a groove that is not parallel to the straight line? The object of the present invention can be achieved even with a simple combination.

Furthermore, as another application example, as shown in FIG. 11, the main surface of the substrate is divided into four parts, for example, regions 1 and 3 are regions with grooves parallel to the X axis, and regions 2 and 4 are arranged along the Y axis. An example is shown in which the area is divided into areas having parallel V grooves.

In this example as well, various combinations can be obtained by, for example, matching the directions of the grooves in regions 1 and 2 and regions 3 and 4, or by switching the directions of the grooves in each region.

Furthermore, as shown in FIG. 12, it is also possible to divide the main surface of the substrate into regions and to combine the directions of the V-grooves in each region.

In FIGS. 11 and 12, the main surface of the substrate is covered with one of these, but a plurality of these may be combined to cover the main surface of the substrate.

So far, we have talked about (1) grooves, but it goes without saying that this is also effective when the corrugated substrate is made thinner by using U grooves, rectangular grooves, etc. Also, the substrate is Si
The same thing can be said not only when the substrate is made of a glass substrate or a compound semiconductor.

〔Example〕

Hereinafter, an embodiment of the present invention will be described using FIG. 13.

This embodiment uses a structure consisting of square areas of two sizes, small and large, as explained in FIG. Each region is divided into regions having vertical and horizontal V-grooves, as indicated by broken lines in the figure. One side a of the large square was 20 mm, and one side a of the small square was 10 mm. Furthermore, at the boundaries of each region, the grooves intersect with each other as shown in the enlarged view, and the pitch C of the grooves is 240 μm. A 250 μm thick Si single crystal substrate with a (100) surface was used as the substrate, and an oxide film with a thickness of 1,000 μm was formed on the front and back surfaces by a normal thermal oxidation method. A thin wire having a width of 20 μm was processed in the direction shown by the broken line in the figure.

This detail is shown by the solid line in the enlarged view of the figure. The oxide film on the back side was formed in the same way as on the front side, with a half period shift from the thin line pattern on the front side. Using this oxide film as an etching mask, Si was anisotropically etched with a hydrazine solution as shown in Figure 2A.
A corrugated cross section as shown in cross section A' was formed. As a result, the substrate thickness becomes 50 μm.

As can be seen from Fig. 13, by combining a region with vertical grooves and a region with horizontal grooves, any cross section of the element always includes a vertical ■ groove and a horizontal V groove, so that the element It was able to maintain extremely high strength against shocks during manufacturing and handling, as well as stress applied after being incorporated into equipment. In this embodiment, a method of forming grooves by anisotropic etching has been described; however, machining such as dicing or laser scribing may also be used. In this case, since anisotropic etching is not used, a wafer having a surface other than the (100) surface may be used. Further, instead of a V-groove, a U-groove or other cross-sectional shape may be used.

Further, in this embodiment, the Si crystal substrate is described, but the substrate is not limited to Si crystal, but may be a compound semiconductor such as GaAs or InP, Ge crystal, or the like.

Further, these substrates are not limited to single crystal substrates, and may be polycrystalline substrates. Furthermore, in a structure in which a single-crystal, polycrystalline, microcrystalline, or amorphous photoelectric conversion layer is formed on a glass or ceramic substrate, by making the substrate have the structure of the present invention, the strength can be maintained even if the substrate is made thin. It can be made higher.

〔Effect of the invention〕

When producing a solar cell with a relatively large area using a very thin substrate, a corrugated structure with a V-groove in one direction does not have sufficient mechanical strength in a specific direction. However, by adopting the structure of the present invention, the mechanical strength of the solar cell became extremely high against stress from all directions.

[Brief explanation of drawings]

FIG. 1 shows an example of the structure of the present invention. Figure 2 shows an example of a conventional structure. FIG. 3 shows an example of the structure of the present invention. FIG. 4 shows an example of the structure of the present invention. FIG. 5 shows an example of the structure of the present invention. FIG. 6 shows an example of the structure of the present invention. FIG. 7 shows an example of the structure of the present invention. FIG. 8 shows an example of the structure of the present invention. FIG. 9 shows an example of the structure of the present invention. FIG. 10 shows an example of the structure of the present invention. FIG. 11 shows an example of the structure of the present invention. FIG. 12 shows an example of the structure of the present invention. FIG. 13 shows an embodiment of the present invention. Explanation of symbols 1. 2, 3, 4, 5, 6, 11, 12, 13゜14...
・■Groove formation area, 20-V groove, 100...Cross beam. Figure 2 Group β β'B'H plane 6 /ρθ 70 zoom t-m No. 31121 Figure 4 V, Q recognition 6th figure '7 Figure g, tJ /;,,',3 Nono --- 〆〆 1 Formation Tower Figure q Figure 10 Figure 11 Figure 2 Figure 13

Claims (1)

[Claims] 1. Structure of a corrugated solar cell substrate characterized in that, on a straight line that arbitrarily crosses the main surface of a substrate having a plurality of grooves, there are grooves that are not substantially parallel to the straight line. . 2. A structure of a corrugated solar cell substrate, characterized in that the substrate having grooves has grooves that are orthogonal to each other. 3. A structure of a corrugated solar cell substrate, characterized in that, in the substrate having the grooves, the grooves having mutually different directions are surrounded by different regions. 4. A structure of a corrugated solar cell substrate, characterized in that, in the substrate having grooves, a groove oriented in a specific direction is partially provided with a groove region having a direction different from the groove.