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Improved polycrystalline texturing composition and method

A composition and compound technology, applied in chemical instruments and methods, surface etching compositions, semiconductor devices, etc., can solve the problems of waste hazards, high industrial cost environment, dangerous exothermic reactions, etc. Efficiency and performance, effect of incident light reflectivity reduction

Active Publication Date: 2012-12-26
SUN CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is an exothermic reaction that can be dangerous to workers handling these acids
In addition, the flowing bath of the acid mixture involves a large amount of acid supplementation and generates a large amount of acid waste, which leads to high costs for the industry and waste hazards to the environment
Generally, a polysilicon semiconductor wafer treated with a mixture of hydrofluoric acid and nitric acid and having an average reflectance of 27% at a light wavelength of 400nm-1100nm is acceptable to the industry; however, the lower the reflectivity, the more solar cells efficient

Method used

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  • Improved polycrystalline texturing composition and method
  • Improved polycrystalline texturing composition and method
  • Improved polycrystalline texturing composition and method

Examples

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preparation example Construction

[0025] In the manufacture of photovoltaic devices or solar cells, the entire backside of the polycrystalline semiconductor wafer may be coated with metal, or part of the backside may be coated with metal to form a grid. This backside metallization can be accomplished using a variety of techniques and can be done prior to the metallization of the front side of the wafer. In one embodiment, a metallic coating is applied on the backside in the form of a conductive paste such as a silver-containing paste, an aluminum-containing paste or a silver-containing aluminum paste; however, other suitable pastes known in the art may also be used. Typically, these conductive pastes include conductive particles embedded in a glass matrix and an organic binder. Conductive paste can be applied to the wafer by various techniques such as screen printing. After applying the conductive paste, it is fired to remove the organic binder. Aluminum can be alloyed with silver when using a conductive pas...

Embodiment 1

[0048] An isotropic texturing aqueous solution includes 10% hydrofluoric acid and 50% nitric acid. The pH of the acidic mixture texturing solution is less than 1. Use a conventional analytical balance to weigh 125mm 2 bulk doped polysilicon wafers and record their weights. The wafer was then immersed in the aqueous isotropic texturing solution at 10°C for 3 minutes. The wafer was then removed from the solution, rinsed with deionized water for 1 minute and dried at room temperature. Weigh the wafer. Based on the weight loss during texturing, the area of ​​the wafer and the density of the silicon, the amount of etching on both sides of the wafer was calculated to be 4.5 μm using conventional methods. figure 1 5000X SEM of the surface of the textured wafer. There are no visible exposed grain boundaries.

[0049] Then utilize the MacBeth ColorEye TM A reflectometer measures the reflectivity of the wafer. Reflectance was recorded in 10 nm increments over the incident light ...

Embodiment 2

[0051] The following isotropic acidic aqueous texturing solutions were prepared.

[0052] Table 1

[0053] Element

Content-weight%

tetramethylammonium hydroxide

7.5％

hydrogen peroxide

1％

ammonium bifluoride

15％

water

margin

[0054] Weigh the bulk-doped polysilicon wafer and record its weight. It was then immersed in the solution at 80° C. for 10 minutes. The pH of the solution was 4. The wafer was then removed from the solution, rinsed with deionized water and air dried. The wafer was weighed and the amount of silicon etched from each side of the wafer was determined to be 4.73 μm. figure 2 Shown is the surface of the textured wafer. There are no visible exposed grain boundaries.

[0055] Then utilize the MacBeth ColorEye TM A reflectometer measures the reflectivity of the wafer. Reflectance was recorded in 10 nm increments over the wavelength range from 1100 nm down to 400 nm. The reflectomete...

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Abstract

An aqueous acidic composition which includes alkaline compounds, fluoride ions and oxidizing agents is provided for texturing polycrystalline semiconductors. Methods for texturing are also disclosed. The textured polycrystalline semiconductors have reduced reflectance of light incidence.

Description

technical field [0001] The present invention relates to an improved acidic polycrystalline semiconductor texturing composition and method. In particular, the present invention relates to an improved acidic polycrystalline semiconductor texturing composition and method that provide isotropic etching and reduce reflectance of incident light. Background technique [0002] Typically, polycrystalline semiconductor wafers are made of silicon or other similar ceramic materials and have grain sizes ranging from a few thousand angstroms to 2-3 μm. Such wafers can be used in the fabrication of optoelectronic devices, such as solar cells. A solar cell is a device that converts light energy, such as sunlight, incident on its surface into electrical energy. Polycrystalline silicon semiconductor wafers are produced using a chemical vapor deposition process in which silane is decomposed at high temperature onto the substrate surface to form an ingot or similar type of item. The ingot is...

Claims

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Application Information

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IPC IPC(8): C23F1/24C09K13/00H01L21/306
CPCH01L31/0236C09K13/08
Inventor R·K·巴尔C·欧康纳
Owner SUN CHEM CORP
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