CN102651408A - A solar substrate for improved burst strength - Google Patents

Abstract

The invention discloses a solar substrate for improving rupture strength, which comprises an upper surface, a plurality of first convex structures and a plurality of first concave regions. The first protruding structures are formed on the upper surface. Each first concave region is formed around the first convex structures. The combination of the first convex structure and the first concave region improves the rupture strength of the solar substrate, thereby resisting the high-tension bending.

Description

A solar substrate for improved burst strength

technical field

The present invention relates to a solar substrate, and more particularly to a solar substrate for improving fracture strength.

Background technique

Generally speaking, conventional solar cells mostly use semiconductor wafers such as silicon as substrates. However, since silicon and other semiconductor wafers are hard and brittle materials, they are easily impacted by external forces, especially those caused by the solar cell assembly process, resulting in cracking of silicon and other semiconductor wafers. In addition to solar cells, silicon wafers are widely used in the manufacture of many semiconductor components. In addition, due to the shortage of silicon raw materials due to the increase in demand for semiconductor components, how to avoid undue waste of silicon raw materials (such as cracking due to external impact) and improve the yield of the process is an urgent problem to be solved. Taking a solar cell as an example, if the solar cell can be fabricated on a substrate with high rupture strength, the possibility of substrate cracking during the subsequent assembly process of the solar cell can be reduced.

Please refer to FIG. 1A and FIG. 1B . 1A to FIG. 1B are pictures taken during the process of testing the rupture strength of a conventional silicon wafer test piece. Silicon wafer coupons are made of single crystal silicon. When the test piece is stressed, the stress will be concentrated in the local area of the test piece, and when the stress gradually increases, cracks will start to appear in these areas (especially the tensioned area). As the load increases, the phenomenon of crack propagation (crack propagation) tends to be obvious, and finally the test piece is broken into several pieces, as shown in Figure 1B.

Because the known silicon wafer test piece can produce the phenomenon that the stress concentrates on the local area of the test piece when it is stressed, if the silicon wafer test piece can be made to distribute the stress evenly on the whole test piece when it is stressed, then The rupture strength of the silicon wafer test piece is bound to be improved. Therefore, the main purpose of the present invention is to provide a solar substrate to solve the above problems.

Contents of the invention

An object of the present invention is to provide a solar substrate for improving the rupture strength, wherein a first protruding structure and a first recessed region are formed on the upper surface thereof, so as to enhance the rupture strength of the solar substrate.

According to a specific embodiment of the present invention, the present invention provides a solar substrate with high rupture strength, which includes an upper surface, a plurality of first protruding structures, and a plurality of first recessed regions. The first protruding structures are formed on the upper surface. Each first recessed area is formed around the first protruding structures. In the present invention, through the combination of the first protruding structure and the first concave region, the rupture strength of the solar substrate is improved, so as to resist high tension bending. In addition, the upper surface is the tension surface of the solar substrate. In addition, the solar substrate is an amorphous substrate, a single crystal substrate or a polycrystalline substrate, specifically, a single crystal substrate and a single crystal silicon substrate. Moreover, the first protruding structure may be a plurality of nanopillars or a plurality of nanoneedles, wherein the distance between the tops of two adjacent nanopillars or nanoneedles is between tens of nanometers and hundreds of nanometers.

According to another specific embodiment of the present invention, the solar substrate with high rupture strength of the present invention further has a lower surface, and the lower surface has a plurality of second raised structures and a plurality of second depressed regions, and each second depressed Regions are formed around the second protruding structures.

To sum up, the present invention provides a solar substrate for improving the rupture strength. The substrate has a combination of a first raised structure and a first recessed area, so that the stress intensity that the substrate can withstand is improved, and the solar energy is also improved. The rupture strength of the substrate, which can reduce the possibility of the solar substrate cracking in the subsequent process of making solar cells.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

Description of drawings

FIG. 1A and FIG. 1B are pictures taken during the process of testing the rupture strength of a conventional silicon wafer test piece.

FIG. 2A shows a cross-sectional view of a solar substrate according to an embodiment of the present invention.

FIG. 2B is a cross-sectional view of a solar substrate according to another embodiment of the present invention.

FIG. 2C is a cross-sectional view of a solar substrate according to another embodiment of the present invention.

FIG. 2D is a cross-sectional view of a solar substrate according to another embodiment of the present invention.

Fig. 3 is a picture of the appearance of the first protrusion structure of the solar substrate according to the present invention.

FIG. 4A and FIG. 4B are pictures taken during the test of the rupture strength of the solar substrate according to the present invention.

5A and 5B are the test data of the solar substrate according to the present invention in the rupture strength test.

FIG. 6A shows a cross-sectional view of a solar substrate according to the present invention when it is bent.

FIG. 6B illustrates actual data of the maximum stress that a raised structure can withstand for a solar substrate.

Explanation of reference signs:

1: Solar substrate

10a: Upper surface 10b: Lower surface

102: The first raised structure 122: The second raised structure

104: The first sunken area 124: The second sunken area

102a: Nanoneedles 102b: Nanocolumns

102a': Nanoneedle population 102b': Nanopillar population.

Detailed ways

Please refer to FIG. 2A . FIG. 2A is a cross-sectional view of a solar substrate according to a specific embodiment of the present invention. As shown in the figure, the solar substrate 1 of the present invention includes an upper surface 10a, a plurality of first protruding structures 102 and a plurality of first recessed regions 104 . Each first protruding structure 102 is formed on the upper surface 10a. Each first recessed area 104 is formed around the first protruding structures 102 . The above-mentioned components will be described in detail below.

The solar substrate 1 of the present invention is an amorphous substrate, a single crystal substrate or a polycrystalline substrate. In practice, the solar substrate 1 is often based on semiconductor wafers such as silicon, that is, the solar substrate 1 can be an amorphous silicon substrate, a single crystal silicon substrate, or a polycrystalline silicon substrate. Here, the present invention is not limited to the solar substrate 1 made of silicon, as long as the solar substrate 1 can be applied to the semiconductor manufacturing process of solar cells and can be processed later, it should belong to the purpose of the present invention. For example, the solar substrate 1 of the present invention can be made of glass (SiO ₂ ), silicon (Si), germanium (Ge), carbon (C), aluminum (Al), gallium nitride (GaN), gallium arsenide (GaAs) , gallium phosphide (GaP), aluminum nitride (AlN), sapphire, spinel, aluminum oxide (Al ₂ O ₃ ), silicon carbide (SiC), zinc oxide (ZnO), Magnesium oxide (MgO), lithium aluminum oxide (LiAlO ₂ ), lithium gallium oxide (LiGaO ₂ ) or magnesium aluminum oxide (MgAl ₂ O ₄ ), but not limited thereto. In addition, the solar substrate 1 of the present invention can be a P-type semiconductor layer, and an N-type semiconductor layer can be formed on the solar substrate 1 to subsequently manufacture a solar cell.

In addition, the upper surface 10 a of the solar substrate 1 can be further defined as a tension surface of the solar substrate 1 . Here, when pressure is applied to the surface of one side of the solar substrate 1, the surface that directly bears the pressure is the pressure receiving surface, and the pressure receiving surface shrinks and deforms inwardly due to the pressure; The back side is the tension surface, and the tension surface is stretched and deformed due to pressure. In practice, due to the structure of the solar substrate 1 in the present invention, when it is matched with a solar cell for subsequent fabrication, the rupture strength of the solar cell can be improved. Therefore, the present invention is not particularly limited to the upper surface 10a, as long as the rupture strength of the solar substrate 1 can be improved, any suitable surface of the solar substrate 1 can be the upper surface 10a.

Please refer to FIG. 2B , which is a cross-sectional view of a solar panel according to another embodiment of the present invention. As shown in the figure, the solar substrate 1 of the present invention further has a lower surface 10 b , a plurality of second protruding structures 122 and a plurality of recessed regions 124 . Each second recessed area 124 is formed around the second protruding structures 122 . The lower surface 10b of the solar substrate 1 of the present invention can be further defined as the pressure-bearing surface of the solar substrate 1 . In practice, the same manufacturing process can be used for the first protruding structure 102 and the second protruding structure 122 , so that the structure thicknesses on both sides of the solar substrate 1 are approximately equal.

From a microscopic point of view, the first protruding structure 102 further includes many nanostructures, and these nanostructures cooperate with the concave region 104 to increase the rupture strength of the solar substrate 1 .

Please refer to Figure 2A to Figure 2D. FIG. 2C is a cross-sectional view of a solar substrate according to another embodiment of the present invention. FIG. 2D is a cross-sectional view of a solar substrate according to another embodiment of the present invention. As shown in the figure, in the upper surface 10a of the solar substrate 1 of the present invention, the first raised structure 102 can be a plurality of nanostructures, and the shape of the nanostructures can be formed as a nanoneedle (nanotip) 102a in FIG. 2A or as shown in FIG. Nanopillar (nanorod or nanopillar) 102b in FIG. 2C. It is worth noting that the solar substrate 1 of the present invention has an upper surface 10a, and the nanoneedles 102a or nanopillars 102b are formed by etching downward from the upper surface 10a of the solar substrate 1 . The aforementioned etching can be any etching process suitable for the substrate of a solar cell, for example, the etching process can be an electrochemical etching process. However, the etching of the upper surface 10a of the solar substrate 1 is not limited to only producing nanoneedles 102a or only nanopillars 102b; on the contrary, nanoneedles 102a and nanopillars 102b can appear on the upper surface 10a at the same time.

In addition, besides the nanoneedles 102a and the nanopillars 102b can be separately formed on the upper surface 10a of the solar substrate 1, a plurality of nanoneedles 102a or a plurality of nanopillars 102b can also be connected to each other to form a nanoneedle group 102a' or a nanopillar Population 102b'. Wherein, the distance between the tops of two adjacent nanoneedles 102a and nanocolumns 102b can be between tens of nanometers and hundreds of nanometers, and each nanoneedle 102a and nanocolumn 102b can have a height of one micron level . Here, the distance between the tops of two adjacent nanoneedles 102a or nanopillars 102b can be defined as an aspect ratio R1 compared to the height of the nanoneedles 102a or nanopillars 102b, and the aspect ratio R1 can be determined by the etching process. It is determined by etching parameters, such as etching time and etching temperature. According to the experimental results, the aspect ratio R1 may be greater than 1.5. In a preferred embodiment, the aspect ratio R1 may be in the range of 2-4.

In other words, the solar substrate 1 of the present invention forms a plurality of nanoneedles 102a or nanopillars 102b on its upper surface 10a, so the nanoneedles 102a or nanopillars 102b can be made of the same material as the solar substrate 1 . In a specific embodiment, if the solar substrate 1 is a single crystal silicon substrate, the upper surface 10 a of the single crystal silicon substrate may have a crystallographic orientation of [100] or [111]. Through the formation of the nanoneedles 102a or the nanopillars 102b, the rupture strength of the solar substrate 1 itself is improved. It is worth mentioning that, if the solar substrate 1 is composed of multiple layers of different materials, the nanoneedles 102 a or the nanopillars 102 b can be any suitable material suitable for the substrate of the solar cell 1 .

On the other hand, the nanostructures formed on both sides of the solar substrate 10 can also be viewed from a microscopic point of view. Please refer to Figure 2B and Figure 2D. As shown in the figure, in the lower surface 10b of the solar substrate 1 of the present invention, the second protruding structure 122 can be a plurality of nanostructures, and the shape of the nanostructures can form the same nanoneedle (nanotip) 102a or 102a in FIG. 2A. As shown in FIG. 2C, a nanopillar (nanorod or nanopillar) 102b is omitted here. Here, compared with FIG. 2A and FIG. 2C , the embodiment disclosed in FIG. 2B and FIG. 2D that both surfaces have nanostructures can further improve the rupture strength of the solar substrate 1 of the present invention by about 15%. In other words, if both surfaces of the solar substrate 1 have nanostructures, the surface of the substrate 1 can withstand greater external force without breaking.

Also, see Figure 3. Fig. 3 is a picture of the appearance of the first protrusion structure of the solar substrate according to the present invention. The plurality of first protruding structures 102 of the present invention can be densely formed with nanoneedles 102 a and nanopillars 102 b on the upper surface 10 a of the solar substrate 1 . It should be noted that the nanoneedles 102 a and the nanopillars 102 b can be regularly or irregularly formed on the upper surface 10 a of the solar substrate 1 . In practical applications, the nanoneedles 102a and the nanopillars 102b can be formed through the aforementioned electrochemical etching process.

Moreover, the solar substrate 1 of the present invention may further include a first microstructure layer and a second microstructure layer (not shown in the figure), and the first microstructure layer may be formed on the upper surface 10a and the first protruding structure 102 , and the second microstructure layer is formed between the lower surface 10 b and the second protruding structure 122 .

The rupture strength of the solar substrate 1 of the present invention can be obtained through a three-point bending strength test. Please refer to FIG. 4A and FIG. 4B. FIG. 4A and FIG. 4B are pictures taken in the process of testing the rupture strength of the solar substrate 1 according to the present invention. In this testing process, the test piece is illustrated as a test piece of a single crystal silicon wafer, and the surface of the tested single crystal silicon wafer has a crystallographic orientation of [100] or [111].

As shown in FIGS. 4A to 4B , when the load on the test piece exceeds the limit, the test piece will be crushed and broken. This phenomenon indicates that the specimen ruptured after absorbing a large amount of energy. As can be inferred from the comparison of the breakage of bulletproof glass and ordinary glass, the test pieces in FIGS. 4A to 4B have a greater breaking strength than the test pieces in FIGS. 1A to 1B .

Please refer to FIG. 5A and FIG. 5B . 5A and 5B are the test data of the solar substrate in the burst strength test according to the present invention. The present invention is illustrated by taking solar substrates with [100] and [111] crystallographic orientations as an example. It should be noted that when the test piece bears a load, cracks usually appear on the tensioned surface and extend to other places. Therefore, the present invention tests the rupture strength of the substrate with nanostructures formed on the tensioned surface.

As shown in Figure 5A and Figure 5B, regardless of the crystal orientation of the silicon wafer [100] or [111], the measured fracture strength has been greatly improved, which proves the shattering fracture of the test piece in Figure 4A to Figure 4B Indeed, it means that the solar substrate according to the present invention has greater rupture strength than the conventional single crystal silicon wafer. In addition, the two surface types of silicon wafers have approximately the same Young's modulus, indicating that the solar substrate according to the present invention does not need to change the nature of the material, and only the surface treatment of the silicon wafer to form nanostructures can improve its rupture strength.

The possible reason why the rupture strength of the solar substrate of the present invention can be greatly improved by forming the first protruding structure or the second protruding structure and the first concave region or the second concave region on the upper or lower surface of the solar substrate of the present invention That is, when the solar substrate bears a load, the stress can be evenly distributed in the recessed area, instead of being distributed in a local area as traditionally.

For example, the traditional solar substrate with a thickness of 6 inches and 200 microns generally cannot be bent. However, the present invention enables the solar substrate of the present invention to produce a certain degree of deformation. See Figure 6A. FIG. 6A shows a cross-sectional view of a solar substrate according to the present invention when it is bent. As shown in FIG. 6A , when the solar substrate of the present invention is subjected to an external force, since the first or second protruding structure and the first or second concave region can disperse the stress received, the solar substrate of the present invention can be bent and deformed. In addition, the invention can further integrate the solar cell manufacturing process, so that the solar cell has greater industrial utilization value.

See Figure 6B. FIG. 6B illustrates actual data of the maximum stress that a raised structure can withstand for a solar substrate. As shown in Figure 6B, Type 1 indicates that the solar substrate is monocrystalline silicon and does not have a first protrusion structure; Type 2 indicates that the solar substrate is monocrystalline silicon and has first and second protrusions on both the tension surface and the pressure surface. Structure; type three means that the solar substrate is monocrystalline silicon and the pressure surface has a second convex structure; type four means that the solar substrate is monocrystalline silicon and the tension surface has a first convex structure. It can be seen from the above chart that when the tension surface of the solar substrate has the first convex structure, the stress intensity that the solar substrate can bear can be greatly improved, and when the tension surface and the pressure surface of the solar substrate both have the first convex structure When the first and second protrusion structures are used, the negative impact of external stress on the solar substrate can be further reduced.

To sum up, the solar substrate according to the present invention can bear a larger load and has excellent rupture strength compared with conventional solar substrates. Therefore, compared with the prior art, the solar substrate according to the present invention has a high bursting strength, so it is more resistant to the impact of external force without cracking. Thereby, the solar substrate according to the present invention can fully improve the yield rate of the manufacturing process, and avoid unnecessary waste of raw materials due to improper impact.

Through the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, the intention is to cover various changes and equivalent arrangements within the scope of the claimed patent scope of the present invention. Therefore, the scope of the claimed scope of the present invention should be interpreted in the broadest way based on the above description, so as to cover all possible changes and equivalent arrangements.

Claims (13)

1. A solar substrate for improving burst strength, comprising: an upper surface; a plurality of first raised structures formed on the upper surface; and A plurality of first recessed regions, each first recessed region is formed around the first raised structures; Wherein, the solar substrate has bends that resist high tension. 2. The solar substrate as claimed in claim 1, wherein the upper surface is a tension surface of the solar substrate. 3. The solar substrate as claimed in claim 1, wherein the solar substrate is an amorphous substrate, a single crystal substrate or a polycrystalline substrate. 4. The solar panel as claimed in claim 3, wherein the single crystal substrate is a single crystal silicon substrate. 5. The solar substrate as claimed in claim 1, wherein the first protrusion structures are a plurality of nanopillars or a plurality of nanoneedles. 6 . The solar substrate as claimed in claim 5 , wherein the distance between the tops of two adjacent nanopillars or nanoneedles is between tens of nanometers and hundreds of nanometers. 7. The solar substrate as claimed in claim 5, wherein the plurality of nanopillars or the plurality of nanoneedles are formed by an electrochemical etching process. 8. The solar substrate as claimed in claim 3, wherein the solar substrate is made of glass, silicon, germanium, carbon, aluminum, gallium nitride, gallium arsenide, gallium phosphide, aluminum nitride, sapphire, spinel , aluminum oxide, silicon carbide, zinc oxide, magnesium oxide, lithium aluminum dioxide, lithium gallium dioxide, and aluminum magnesium oxide made of one of the group. 9. The solar substrate as claimed in claim 1, wherein the solar substrate further has a lower surface, the lower surface has a plurality of second raised structures and a plurality of second recessed regions, each second recessed region is formed on the around the second raised structure. 10. The solar substrate as claimed in claim 9, wherein the lower surface is a pressure-bearing surface of the solar substrate. 11. The solar substrate as claimed in claim 1, wherein the solar substrate can be a P-type semiconductor layer, and an N-type semiconductor layer can be formed on the solar substrate. 12. The solar substrate as claimed in claim 1, wherein the solar substrate further comprises a first microstructure layer formed between the upper surface and the first protrusion structures. 13. The solar substrate as claimed in claim 9, wherein the solar substrate further comprises a second microstructure layer formed between the lower surface and the second protrusion structures.

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