WO2015081876A1

WO2015081876A1 - Solar battery surface texturing processing method

Info

Publication number: WO2015081876A1
Application number: PCT/CN2014/093051
Authority: WO
Inventors: 骆志炯
Original assignee: 骆志炯
Priority date: 2013-12-05
Filing date: 2014-12-04
Publication date: 2015-06-11
Also published as: CN104701407A; CN104701407B

Abstract

A solar battery surface texturing processing method comprises the following steps: a, providing a silicon wafer (1) and an etching agent (2); b, placing the silicon wafer in a reaction chamber in which the etching agent is placed or above the etching agent to perform chemical vapor etching, or immersing the silicon wafer in the etching agent to perform liquid phase etching; and c, repeating step b at least once. In this texturing processing method, better heterogeneity can be formed, and therefore a good porous layer can be obtained for a silicon wafer in another crystal orientation, thereby obtaining a lower luminous reflectance.

Description

Surface finishing treatment method for solar battery

Technical field

The invention relates to the field of preparation of crystalline silicon solar cells, and in particular to a surface texturing treatment method for a surface texturing treatment method of a solar cell.

Background technique

As an efficient green sustainable energy source, solar cells have been widely studied and utilized. However, since the manufacturing cost of solar cells is too high to replace traditional energy sources, cost reduction has become the biggest problem in solar cell applications. The cost of solar cells is closely related to the efficiency of the battery. Therefore, how to improve the conversion efficiency of the battery is the key to the further development of the solar cell industry. Conventional silicon wafers have a high refractive index, and their reflection loss can generally reach more than 40%. In the previous solar cell fabrication process, it was proposed to make a silicon wafer into a surface having a suede surface in order to increase the light trap rate, but such a The reflectivity of the silicon wafer is also about 10%.

Current mainstream silicon substrate texturing techniques include (1) single crystal silicon alkali texturing, (2) ion reactive etching (RIE) dry texturing, and (3) wet acid texturing.

Alkali texturing involves the reaction of anisotropic physical properties of a single crystal structure to form a randomly arranged pyramidal surface topography.

Ion reactive etching (RIE) is a dry method of fluffing. By the reaction of plasma, the generated ions bombard the surface of the silicon wafer to obtain a set surface topography to reduce the reflection of light. If you use a mask, you will get better results.

Wet acid velvet is the current mainstream velvet technology, which has a good effect compared to alkali velvet. The main advantage of wet acid velvet is low cost. Acid velvet uses HF/HNO3 combination to react with the surface of polycrystalline silicon to form a small crater-like morphology and reduce reflection. Therefore, it has good application value. However, at present, wet acid texturing is usually carried out by using KOH for single crystal silicon in the crystal orientation (100) and an acid such as HF/HNO3 as an etchant for polycrystalline silicon. However, neither of the two etchants can better etch the other crystalline single crystal silicon.

Therefore, it is necessary to propose a new method for surface-finishing the surface of a solar cell, which can process other single crystal silicon.

Summary of the invention

In order to solve the above technical problems, the present invention proposes a surface texturing processing method for a solar cell, specifically:

The invention provides a surface finishing treatment method for a solar cell, comprising the steps of: a, providing a silicon wafer and an etchant; b, placing the silicon wafer in a reaction chamber or a chamber in which the etchant is placed; Performing a chemical vapor etching over the etchant or immersing the silicon wafer in the etchant for liquid phase etching; c, repeating step b at least once.

Wherein, the etchant is: a mixture of HNO ₃ and H ₂ O having a concentration of 30-65% and a concentration of 45-85% in a weight ratio of substantially 1:3:8-1:8:3; H ₂ SO ₄ may be added to the etchant or one of HF or HNO ₃ may be replaced in whole or in part by H ₂ SO ₄ .

The invention also provides a surface finishing treatment method for a solar cell, comprising the steps of: a, providing a silicon wafer and a plurality of etchants; b, placing the silicon wafer in a certain etchant; Performing a chemical vapor etch in the reaction chamber or some kind of the etchant or immersing the silicon wafer in an etchant for liquid phase etching; c, repeating step b at least once, wherein in the repetition In the step, the same or different etchant used in the previous etching may be selected for chemical vapor etching or liquid phase etching.

Wherein, the etchant comprises: (1) a weight of 30-65% HF, a concentration of 45-85% of HNO ₃ and H ₂ O at a weight of substantially 1:3:8-1:8:3 (2) adding H ₂ SO _{4 to} the etchant described in (1) or replacing all of HF or HNO ₃ by H ₂ SO _{4 in} whole or in part.

In the surface finishing treatment method of the above two types of solar cells, the etchant includes silicon, germanium, or other semiconductor material in the chemical vapor phase etching step. In the chemical vapor phase etching step, the temperature of the etchant is set between 0 and 85 degrees.

The surface treatment method for the surface of the solar cell of the present invention can form better non-uniformity due to better chemical reaction and fogging under vapor phase etching, and therefore, can be used for other non-(100) crystal orientation silicon wafers. A better porous layer is obtained to achieve a lower light reflectance.

The chemical vapor vapor phase etching method of the present invention is simple and feasible, and can be used in combination with wet etching for better results.

The additional aspects and advantages of the invention will be set forth in part in the description which follows.

DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a schematic view showing a chemical weather etching of step b of an embodiment of a surface texturing treatment method for a solar cell of the present invention;

2 is a schematic view showing liquid phase etching of step b of an embodiment of a surface texturing treatment method for a solar cell of the present invention;

Fig. 3 is a view showing the effect of the field experiment of the present invention.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting. The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and arrangements of the specific examples are described below. Of course, they are merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in different examples. This repetition is for the purpose of simplicity and clarity, and is not in the nature of the description of the various embodiments and/or arrangements discussed. Moreover, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the applicability of other processes and/or the use of other materials. Additionally, the structure of the first feature described below "on" the second feature may include embodiments in which the first and second features are formed in direct contact, and may include additional features formed between the first and second features. Embodiments such that the first and second features may not be in direct contact.

According to an embodiment of the present invention, a method for surface-finishing a solar cell surface is provided, comprising: step a, providing an etchant and a silicon wafer. The etchant may be prepared by mixing HF with a concentration of 30-65%, HNO ₃ and H ₂ O at a concentration of 45-85% in a weight ratio of substantially 1:3:8-1:8:3. Alternatively, H ₂ SO ₄ may be added to the etchant or one of HF or HNO ₃ may be replaced in whole or in part by H ₂ SO ₄ . Preferably, an etchant is prepared by mixing HF having a concentration of 49%, HNO ₃ and H ₂ O having a concentration of 70% in a weight ratio of 1:5.3:3.3, and the etchant is in the chemical vapor phase. Silicon, germanium, or other semiconductor materials are included in the etching step. The silicon wafer has a thickness of 20 to 1000 microns. In particular, in the case of a single crystal, the crystal orientation of the light absorbing surface may be any crystal orientation.

Then, in step b, referring to FIG. 1 or FIG. 2, the silicon wafer 1 is placed above the etchant 2 for chemical vapor etching or the silicon wafer 1 is immersed in the etchant 2 Liquid phase etching. The step b may be a vapor phase etching or a liquid phase etching. For example, the temperature of the etchant is first set between 0 and 85 degrees, preferably ambient temperature, and then the light absorbing surface of the silicon wafer is directed toward the etchant for chemical vapor etching. Or referring to FIG. 2, the silicon wafer is immersed in the etchant for liquid phase etching. Preferably, in the chemical weather etching step, the etchant comprises silicon, germanium or other semiconductor materials.

In the step c, the step b may be repeated a plurality of times, that is, the silicon wafer may be subjected to multiple gas phase or liquid phase etching, for example, multiple gas phase and liquid phase etching may be performed, or, of course, Multiple single types of etching are performed, such as multiple vapor phase etching or multiple liquid phase etching.

As a second embodiment, the present invention further provides a method for surface-finishing a solar cell, comprising: step a, providing a silicon wafer and various etchants; and the etchant may be at a concentration of 30-65% HF, a concentration of 45-85% of HNO ₃ and H ₂ O are mixed in a weight ratio of substantially 1:3:8-1:8:3. Preferably, an etchant is prepared by mixing HF having a concentration of 49%, HNO ₃ and H ₂ O at a concentration of 70% in a weight ratio of 1:5.3:3.3, and other forms of etchant can be prepared. For example, H ₂ SO _{4 is} added to the above etchant or one of HF or HNO ₃ is completely or partially replaced by H ₂ SO ₄ . The etchant includes silicon, germanium, or other semiconductor material in the chemical vapor phase etching step. The silicon wafer has a thickness of 20 to 1000 microns. In particular, in the case of a single crystal, the crystal orientation of the light absorbing surface may be any crystal orientation.

Then, in step b, referring to FIG. 1 or FIG. 2, the silicon wafer 1 is placed on the etchant 2 for chemical vapor etching, or the silicon wafer 1 is immersed in the etchant 2. Liquid phase etching. The step b may be a vapor phase etching or a liquid phase etching. For example, first the temperature of the etchant A temperature between 0 and 85 degrees, preferably ambient temperature, is set, and then the light absorbing surface of the silicon wafer is directed toward the etchant for chemical vapor etching. Or referring to FIG. 2, the silicon wafer is immersed in the etchant for liquid phase etching. Preferably, in the chemical vapor phase etching step, the etchant comprises silicon, germanium or other semiconductor materials.

In the step c, the step b may be repeated a plurality of times, that is, the silicon wafer may be subjected to multiple gas phase or liquid phase etching, for example, multiple gas phase and liquid phase etching may be performed, or, of course, Performing multiple single-type etchings, such as multiple vapor phase etching or multiple liquid phase etching, in which the etchant may be selected to be the same as or different from the etchant used in the previous etching. Perform chemical vapor etching or liquid phase etching.

Referring to FIG. 3, "◆" represents a silicon wafer obtained by the conventional factory standard texturing, and "○" represents a silicon wafer obtained by chemical vapor phase etching according to the surface texturing treatment method of the present invention, and the horizontal axis is The thickness of the silicon wafer, and the vertical axis is the light reflectance of the silicon wafer. It can be seen from the figure that the silicon wafer sample after one vapor phase etching has a significantly lower light reflectance than the original sample.

The solar cell surface texturing treatment method of the present invention has been explained in detail above based on the first and second embodiments of the present invention. Due to better chemical reaction and better non-uniformity in the form of mist during vapor phase etching, a better porous layer can be obtained for other non-(100) crystal orientation silicon wafers, resulting in lower Light reflectivity.

While the invention has been described with respect to the preferred embodiments and the embodiments of the present invention, it is understood that various changes, substitutions and modifications may be made to the embodiments without departing from the spirit and scope of the invention. For other examples, those of ordinary skill in the art will readily appreciate that the order of process steps may vary while remaining within the scope of the invention.

Further, the scope of application of the present invention is not limited to the process, mechanism, manufacture, composition of matter, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be readily understood by those skilled in the art that the processes, mechanisms, manufactures, compositions, means, methods, or steps that are presently present or will be developed in the The corresponding embodiments described have substantially the same function or substantially the same results, which can be applied in accordance with the invention. Therefore, the appended claims are intended to cover such modifications, such structures, structures,

Claims

A method for surface texturing of a solar cell, comprising the steps of:

a, providing a silicon wafer and an etchant;

b. placing the silicon wafer in a reaction chamber in which the etchant is placed or above the etchant for chemical vapor etching or immersing the silicon wafer in the etchant for liquid phase etching;

c. Repeat step b at least once.
The method according to claim 1, wherein the etchant is: HF having a concentration of 30-65%, HNO 3 and H 2 O having a concentration of 45-85% at substantially 1:3:8. A weight ratio of -1:8:3 is mixed, or H 2 SO 4 may be added to the etchant or one of HF or HNO 3 may be completely or partially replaced by H 2 SO 4 .
A method for surface texturing of a solar cell, comprising the steps of:

a, providing silicon wafers and a variety of etchants;

b. placing the silicon wafer in a reaction chamber in which the etchant is placed or a certain etchant, performing chemical vapor etching or immersing the silicon wafer in an etchant. Phase etching

c. Repeat step b at least once, wherein in each of the repeating steps, the same or different etchant as that used in the previous etching may be selected for chemical vapor etching or liquid phase etching.
The method according to claim 3, wherein the etchant comprises: (1) HF from a concentration of 30-65%, HNO 3 and H 2 O at a concentration of 45-85% to substantially 1: 3:8-1:8:3 by weight ratio; (2) adding H 2 SO 4 to the etchant described in (1) or replacing HF or HNO 3 by H 2 SO 4 in whole or in part One kind.
The method of claims 1-4, wherein the etchant comprises silicon, germanium, or other semiconductor material in the chemical vapor phase etching step.
The method according to any of claims 1-4, characterized in that in the chemical vapor phase etching step, the temperature of the etchant is set between 0 and 85 degrees.