TW201624741A - Crystalline silicon solar energy chip with low specular gloss and low reflectivity - Google Patents

Abstract

A crystalline silicon solar energy chip with low specular gloss and low reflectivity is disclosed, which comprises: a chip body; a micro-scale structure formed by a roughening treatment for plural micro-scale pores to distribute on the surface of chip body in a pore array; and a nano-scale structure formed by a roughening treatment for plural nano-scale pores to disperse uniformly in the micro-scale structure and the local surface of the chip body, thereby forming a multi-scale texture, and forming a composite structure with the micro-scale structure. Accordingly, the micro-scale pore arrangement structure is applied by the present invention as the substrate to reduce the surface specular gloss (85 DEG < 50 G.U.), and the nano-scale pore-like surface structure is etched on the substrate to form the multi-scale texture, thereby forming the composite structure to reduce the surface reflectivity of wafer.

Description

Crystalline germanium wafer with low gloss and low reflectivity

The invention relates to a crystalline germanium solar germanium wafer with low gloss and low reflectivity, in particular to a micro-scale pore-shaped arrangement as a substrate for reducing the surface gloss of the wafer, and then etching on the substrate. A nano-scale pore-like surface structure forms a multi-scale roughening, forming a composite structure to reduce the surface reflectance of the wafer.

At present, the mainstream of commercial solar cells is crystalline germanium solar cells, which are divided into single crystal germanium (c-Si), mono-like c-Si and polycrystalline (m-Si) crystalline germanium solar cells, which are composed of polycrystalline twins. The wafer-made polycrystalline silicon solar cell has a fast wafer and battery fabrication process, and the cost is lower than that of the single crystal crystallization solar cell. Currently, it is the highest product for commercial solar cells. While single crystal crystallization solar cells have been proven to have higher photoelectric conversion efficiencies relative to polycrystalline solar cells, uneven surface appearance has been one of the main reasons for limiting their development.

Polycrystalline germanium solar cells, currently commercially mass-produced wet acid etching (mixed acid of nitric acid and hydrofluoric acid) to produce a surface texture structure, has a very high competitive advantage in process time cost; however, the use of wet acid When the surface woven structure is etched, the pile surface is disordered, and the white-gray grain is presented. Further, for a part of the surface, the wafer is too flat (low surface roughness) (for example: The film cut by the diamond wire), the wet acid etching method will not effectively reduce the light reflectivity, which is the main reason for further improving its efficiency.

Diamond wire cut is cheaper than traditional mortar cuts. In the past few years, the solar industry has been experimenting with diamond cutting to reduce manufacturing costs, but traditional wet acid etching cannot be effective. Diamond wire cutting solar enamel wafer surface produces low reflection and low gloss appearance, so it has not been accepted by most customers under the consideration of efficiency and appearance factors.

As shown in Figure 5, in order to compare the wafer patterns of different slicing methods, Figure (B) shows the appearance of commercial diamond wire slices, and the comparison chart (A) traditional carbonized mortar mortar slices, the surface average gloss and reflectivity are relatively high. The comparison between the average reflectance and the average gloss is shown in Table 6 below.

Table 6

The commercial wet acid etching process, as shown in Figure 6, has an etch weight of about 0.32 to 0.42 g. It can be seen from Table 7 below that conventional wet acid etching cannot effectively reduce the average reflectance and gloss of polycrystalline germanium wafers. Degree, thus limiting the improvement of battery efficiency.

Table 7

In recent years, in order to escape the traditional wet acid etching, the reflectivity cannot be effectively reduced. Many studies have been carried out to produce nano-scale (roughness less than 900 nm) surface structure by dry etching such as reactive ion etching (RIE). To get a lower reflectivity. However, the nanostructures are formed separately on the wafer surface of the diamond wire slice by using different process conditions. It can be seen from Table 8 and Table 7 that although the average surface reflectance can be effectively reduced, the surface still has an excessively high average gloss; Therefore, the surface appearance of low gloss and low reflection cannot be obtained by the existence of a nanostructure alone.

Table eight

In view of the two main problems encountered in the commercial use of the diamond wire sliced solar wafers at present:

1. Conventional wet acid etching cannot increase the amount of incident light more effectively, resulting in a limitation of efficiency improvement space.

2. Has a high surface gloss.

Therefore, the user-like users cannot meet the needs of the user in actual use.

The main object of the present invention is to overcome the above problems encountered in the prior art and to provide a micron-ordered hole-arranged structure as a substrate to reduce the surface gloss of the wafer, and then to form a nano-scaled surface structure on the substrate. Multi-scale roughening, forming a composite structure to reduce the surface reflectance of the wafer with low gloss and low reflectivity crystalline germanium solar germanium wafers.

For the purpose of the above, the present invention is a low-gloss and low-reflectivity crystalline germanium solar germanium wafer comprising: a wafer body; a micron-scale structure, wherein a plurality of micron-sized holes are presented by a roughening process. a pore-like distribution on the surface of the wafer body to form the micron-scale structure; and a nano-scale structure, wherein a plurality of nano-scale pores are uniformly dispersed in the micro-scale structure and a partial surface of the wafer body by a roughening treatment Roughening of multiple scales and forming a composite structure with the micron-scale structure.

In the above embodiment of the invention, the wafer system is a polycrystalline germanium (m-Si) or mono-like c-Si material.

In the above embodiment of the present invention, the roughening treatment of the micro-scale structure is performed by physically etching or chemically etching the surface of the wafer body; the physical etching is laser, sand blasting, sputter etching, or ion beam Ion Beam Etching, which is a wet chemical acid or alkali etching combined with an etch mask, and the wet chemical used is a combination of various acids or bases, and the acid wet chemical system is Nitric acid, acetic acid, hydrofluoric acid, sulfuric acid, or a mixed acid of any combination, the base wet chemical is potassium hydroxide or sodium hydroxide.

In the above embodiment of the present invention, the roughening treatment of the nano-scale structure is performed by plasma etching, or reactive ion etching (RIE), and the micro-scale structure and the surface of the wafer body. .

In the above embodiment of the invention, the nanostructure is formed by dry etching using a gas containing a chlorine-based gas, a fluorine-based gas, an oxygen-based gas, and hydrogen.

In the above embodiment of the present invention, the fluorine-containing gas system may be sulfur hexafluoride (SF ₆ ), carbon tetrafluoride (CF ₄ ), nitrogen trifluoride (NF ₃ ), and fluorine gas (F _{2 ).} And at least one or more gases of the chlorine-containing gas system may be at least one of chlorine (Cl ₂ ), carbon tetrachloride (CCl ₄ ), and chloroform (CHCl ₃ ), and The oxygen-containing gas system may be at least one of nitrous oxide (N ₂ O), oxygen (O ₂ ), and ozone (O ₃ ).

In the above embodiment of the present invention, the micron-sized holes in the micron-scale structure may be in the shape of a circle, a polygon, a concentric circle, a geometric figure, or a combination of the above various patterns.

In the above embodiment of the invention, the average distance between the geometric centers of adjacent micron-sized holes in each column is less than 200 micrometers (μm).

In the above embodiment of the present invention, the plurality of micron-sized holes are arranged in a straight line, a regular repeating arrangement, a staggered arrangement, or a uniform plum-like arrangement between the columns and the columns.

In the above embodiment of the present invention, the diameter of each micron-sized hole in the micron-scale structure is between 5 and 200 μm, and the vertical depth of each micron-sized hole is between 3 and 30 μm.

In the above embodiment of the present invention, the micron-scale structure formed by the plurality of micron-sized holes occupies more than 50% of the surface area of the wafer body.

In the above embodiment of the invention, the average roughness of the nanostructure is between 5 and 900 nm.

In the above embodiment of the present invention, the diameter of each nanometer-scale hole in the nano-scale structure is between 300 and 500 nm, and the vertical depth of each nano-scale hole is less than 900 nm.

In the above embodiment of the invention, the surface gloss is less than 50 G.U. at a light incident angle of 85°.

In the above embodiment of the present invention, the reflectance between the wavelength bands of the solar spectrum of 300 to 1100 nm can be reduced.

In addition to the above embodiments, the present invention has a low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer, which may be another embodiment including: a wafer body; a micron-scale structure, by a roughness The micro-scale holes are arranged in a row on the surface of the wafer body to form the micro-scale structure; and the multi-layer anti-reflection layer is formed on the surface of the wafer body and covers the plurality of micro-scale holes in the micro-scale structure. .

In the above embodiment of the invention, the multilayer anti-reflective layer is yttrium oxide (SiO _x ), tantalum nitride (SiN _x ), or titanium dioxide (TiO ₂ ).

In the above embodiment of the invention, the average distance between the geometric centers of adjacent micron-sized holes in each column is less than 200 μm.

In the above embodiment of the present invention, the diameter of each micron-sized hole in the micron-scale structure is between 5 and 200 μm, and the vertical depth of each micron-sized hole is between 3 and 30 μm.

In the above embodiment of the present invention, the micron-scale structure formed by the plurality of micron-sized holes occupies more than 50% of the surface area of the wafer body.

1‧‧‧chip body

2‧‧‧micron structure

21‧‧‧micron holes

3‧‧‧n-level structure

31‧‧‧Neon-class holes

4‧‧‧Anti-reflective layer

Fig. 1 is a partially enlarged schematic view showing the structure of a first embodiment of the present invention.

Fig. 2A is a SEM (1) diagram of the nanostructure of the present invention.

Figure 2B is a SEM (b) diagram of the nanostructure of the present invention.

Fig. 3 is a schematic view showing the manufacturing process of the first embodiment of the present invention.

Figure 4 is a cross-sectional view showing the structure of a second embodiment of the present invention.

Figure 5 is a diagram of a wafer with different slicing methods.

Figure 6 is a schematic diagram showing the manufacturing process of a conventional polycrystalline crystallization solar cell.

Please refer to FIG. 1 to FIG. 4, which are respectively a partially enlarged schematic view of the structure of the first embodiment of the present invention, an SEM (1) diagram of the nanostructure of the present invention, and a SEM of the nanostructure of the present invention. (2) A schematic diagram of a manufacturing process of the first embodiment of the present invention and a schematic cross-sectional view of a second embodiment of the present invention. As shown in the figure: the present invention is a low-gloss and low-reflectivity crystalline germanium solar germanium wafer comprising a wafer body 1, a micro-scale structure 2, and a nano-scale (nano-scale). Structure 3 is constructed.

The wafer body 1 mentioned above may be a polycrystalline germanium (m-Si) or a mono-like c-Si material.

The micron-scale structure 2 is such that a plurality of micro-scale holes 21 are arranged in a row of holes on the surface of the wafer body 1 by a roughening process such as physical etching or chemical etching (with an etch mask), and between columns and columns The lines are arranged in a straight line, regularly arranged in a regular arrangement, staggered, or arranged in a uniform plum shape (as shown in Fig. 1), and the average distance between geometric centers of adjacent micron-sized holes 21 in each column is less than 200 micrometers (μm). Thereby, a micron-scale structure 2 constituting 50% or more of the surface area of the wafer body 1 is formed. The plurality of micro-scale holes 21 are semi-recessed holes, and the shape thereof may be a circle, a polygon, a concentric circle, a geometric figure, or a combination of the above various patterns. The diameter of each micron-sized hole 21 is between 5 and 200. Mm, and the vertical depth of each micron-sized hole 21 is between 3 and 30 μm. The physical etching is laser, sand blasting, Sputter Etching, or Ion Beam Etching, and the chemical etching is a wet chemical acid or alkali etching with an etch mask, and is used. The wet chemical is a combination of various acids or bases, and the acid wet chemical is nitric acid, acetic acid, hydrofluoric acid, sulfuric acid, or a mixed acid of any combination, and the alkali wet chemical is hydrogen. Potassium oxide, or sodium hydroxide.

The nano-scale structure 3 is uniformly dispersed in the micro-scale structure by a roughening treatment such as plasma etching or reactive ion etching (RIE). 2 is formed with a partial surface of the wafer body 1 to form a multi-scale roughening, and forms a composite structure with the micro-scale structure 2. The nano-structure 3 can clearly see the nano-scaled surface (as shown in Figures 2A and 2B) via a Scanning Electron Microscope (SEM), and the average roughness (Roughness) is between 5 ～900 nm, the diameter of each nanometer hole 31 is between 300 and 500 nm, and the vertical depth of each nanometer hole 31 is less than 900 nm. The nanostructure 3 is formed by dry etching using a chlorine-containing gas, a fluorine-based gas, an oxygen-based gas, and hydrogen gas, and the fluorine-containing gas system may be six. a gas containing at least one of sulfur fluoride (SF ₆ ), carbon tetrafluoride (CF ₄ ), nitrogen trifluoride (NF ₃ ), and fluorine gas (F ₂ ) may be used in combination with the chlorine-containing gas system. At least one or more of chlorine (Cl ₂ ), carbon tetrachloride (CCl ₄ ), and chloroform (CHCl ₃ ), and the oxygen-containing gas system may be nitrous oxide (N ₂ O), At least one or more of oxygen (O ₂ ) and ozone (O ₃ ). As such, a novel device having a low gloss and low reflectivity crystalline germanium solar cell is constructed by the above disclosed device.

In a specific embodiment, the fabrication process of the micron and nano composite structure of the solar tantalum wafer of the present invention is as shown in FIG. 3. Compared with the conventional technology, as shown in the following Table 1, the present invention can simultaneously obtain low average reflection. Rate and gloss.

Table I

In addition to the composite structure described in the first embodiment, the present invention may also be the configuration of the second embodiment. As shown in FIG. 4, the present invention includes: a wafer body 1, a micron-scale structure 2 And a multilayer anti-reflection layer 4 is formed.

The wafer body 1 and the micron-scale structure 2 mentioned above are as described above.

The multilayer anti-reflective layer 4 is formed on the surface of the wafer body 1 and covers the plurality of micro-scale holes 21 in the micro-scale structure 2. The multilayer anti-reflective layer is yttrium oxide (SiO _x ), tantalum nitride (SiN _x ), or titanium dioxide (TiO ₂ ).

Even if the present invention exists in a micron structure, the presence of the micron structure can effectively produce a low surface gloss solar cell; as shown in Tables 2 and 3 below, the microstructure structure has a depth along the structure and the distance between the structures and the reflectance and the surface. The influence of gloss can be seen from the results presented in Table 2 and Table 3. When the width of the fixed micro-structure is 20 μm and 50 μm respectively, the surface gloss and reflectivity can be reduced simultaneously with the increase of the micro-structure depth; Ground, as the distance between the microstructures increases, the gloss and reflectivity also increase. With respect to the existence of the above-mentioned surface micro-single structure, Table 4 and Table 5 below show the existence of the composite structure, which can more effectively reduce the surface gloss and surface reflectance, wherein Table 4 is based on Table 2 to form a surface composite size on the wafer. The structure forms its optical data, and Table 5 forms its optical data according to Table 3 to form a surface composite size structure on the wafer.

Table II

Table 3

Table 4

Table 5

It can be seen from the above that the composite size surface structure of the present invention can effectively reduce the incident light reflectance and gloss (having less than 50 GU at a light incident angle of 85°), so as to solve the current diamond wire slice solar tantalum wafer in commercial use. There are two major problems with the inability to increase the amount of incident light more effectively, resulting in a space for efficiency improvement, and high surface gloss.

Thereby, the invention reduces the surface gloss of the wafer by using a micron-scale pore-arranged structure as a substrate, and reduces the surface reflectance of the wafer by using a nano-scale structure; wherein the nano-scaled surface is etched on the substrate to form a multi-scale roughness. And forming a solar cell structure having a composite structure, which has the following features:

1. Effectively reduce surface gloss (85° <50 G.U.).

2. Effectively reduce the reflectance of the solar spectrum from 300 to 1100 nm.

3. Increase the contact area between the electrode and the germanium wafer to reduce the battery contact resistance.

In summary, the present invention is a low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer, which can effectively improve various disadvantages of the conventional use, and reduce the surface gloss of the wafer by using a micro-scale hole-shaped arrangement as a substrate. Degree, and then etching a nano-scale pore-like surface structure to form a multi-scale roughening, forming a composite structure to reduce the surface reflectance of the wafer, thereby The invention can be made more progressive, more practical, and more in line with the needs of the user. It has indeed met the requirements of the invention patent application and has filed a patent application according to law.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto; therefore, the simple equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the invention are modified. All should remain within the scope of the invention patent.

1‧‧‧chip body

2‧‧‧micron structure

21‧‧‧micron holes

3‧‧‧n-level structure

31‧‧‧Neon-class holes

Claims (20)

[Item 1] A low-gloss ratio and low reflectivity crystalline germanium solar germanium wafer, comprising:
a wafer body;
a micro-scale structure in which a plurality of micro-scale holes are arranged in a row on the surface of the wafer body to form the micro-scale structure by a roughening treatment; and a nano-scale structure, A plurality of nano-scale holes are uniformly dispersed in the micro-scale structure and a partial surface of the wafer body by a roughening process to form a multi-scale roughening, and form a composite structure with the micro-scale structure. (composited structure). [Item 2] A low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to the first aspect of the patent application, wherein the wafer system is a polycrystalline germanium (m-Si) or a mono-like c-Si material. . [Item 3] a low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to claim 1, wherein the micron-scale roughening treatment is performed by physically etching or chemically etching the surface of the wafer body; It is laser, sandblasting, Sputter Etching, or Ion Beam Etching, which is a wet chemical acid or alkali etching with an etch mask, and the wet chemical used. It is a combination of various acids or bases, and the wet chemical of acid is nitric acid, acetic acid, hydrofluoric acid, sulfuric acid, or a mixed acid of any combination, and the wet chemical of the base is potassium hydroxide or hydrogen. Sodium oxide. [Item 4] A low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to claim 1, wherein the nanostructure is roughened by plasma etching or reactive ions. Reactive Ion Etching (RIE) The micron-scale structure and the surface of the wafer body. [Item 5] a low-gloss ratio and low-reflectivity crystalline ruthenium solar wafer according to item 4 of the patent application scope, wherein the nano-scale structure is a gas containing a chlorine-based gas, a fluorine-based gas, or an oxygen-based gas. And hydrogen gas is formed by dry etching. [Item 6] According to claim 5, the low-gloss ratio and low reflectivity crystalline germanium solar germanium wafer, wherein the fluorine-containing gas system may be sulfur hexafluoride (SF ₆ ) or carbon tetrafluoride (CF). ₄ ), at least one or more of nitrogen trifluoride (NF ₃ ) and fluorine gas (F ₂ ), and the chlorine-containing gas system may be chlorine gas (Cl ₂ ) or carbon tetrachloride (CCl ₄ ). And at least one of chloroform (CHCl ₃ ) and the oxygen-containing gas system may be at least one of nitrous oxide (N ₂ O), oxygen (O ₂ ), and ozone (O ₃ ) Above gas. [Item 7] A low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to claim 1, wherein the micron-scale pores of the micron-scale structure may be circular, polygonal, concentric, or geometric. Or a combination of the above various graphics. [Item 8] The low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to claim 1, wherein the plurality of micron-sized holes have an average distance between geometric centers of adjacent micro-scale holes in each column of less than 200 micrometers. (μm). [Item 9] a low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to the first aspect of the patent application, wherein the plurality of micrometer-sized pores are arranged in a row, a regular repeat, a staggered arrangement, or It is arranged in a uniform plum shape. [Item 10] A low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to claim 1, wherein the micron-sized structure has a diameter of 5 to 200 μm per micrometer. The vertical depth of the graded holes is between 3 and 30 μm. [Item 11] The low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to the first aspect of the patent application, wherein the micron-scale structure formed by the plurality of micron-sized pores occupies more than 50% of the surface area of the wafer body. [Item 12] According to claim 1, the low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafers have an average roughness of 5 to 900 nm. [Item 13] The low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to the first aspect of the patent application, wherein the nanometer-scale pores of the nano-scale structure are between 300 and 500 nm, and each The vertical depth of a nanometer-scale hole is less than 900 nm. [Item 14] According to the scope of claim 1, the low gloss and low reflectivity crystalline germanium solar germanium wafer has a surface gloss of less than 50 G.U. at a light incident angle of 85°. [Item 15] According to the scope of claim 1, the low-gloss ratio and low-reflectivity crystallization solar 矽 wafer can reduce the reflectance between the solar spectrum of 300 to 1100 nm. [Item 16] A low-gloss ratio and low reflectivity crystalline germanium solar germanium wafer, comprising:
a wafer body;
a micron-scale structure, wherein a plurality of micron-sized holes are arranged in a hole shape on the surface of the wafer body to form the micro-scale structure by a roughening treatment; and a multi-layer anti-reflection layer is formed on the surface of the wafer body and covered with The micron-scale structure is on a plurality of micron-sized holes. [Item 17] a low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to claim 16, wherein the multilayer anti-reflective layer is cerium oxide (SiO _x ), tantalum nitride (SiN _x ), or titanium dioxide. (TiO ₂ ). [Item 18] The low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer according to claim 16 wherein the average distance between the geometric centers of adjacent micron-sized holes in each column is less than 200 μm. . [Item 19] A low-luminosity and low-reflectivity crystalline germanium solar germanium wafer according to claim 16 wherein the diameter of each micron-sized hole in the micron-scale structure is between 5 and 200 μm, and each micrometer The vertical depth of the graded holes is between 3 and 30 μm. [Item 20] According to claim 16 of the patent application, there is a low-gloss ratio and low-reflectivity crystalline germanium solar germanium wafer, wherein the micron-scale structure formed by the plurality of micron-sized pores occupies more than 50% of the surface area of the wafer body.