Method for Producing Textures or Polishes on the Surface of Monocrystalline Silicon Wafers

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This invention describes a method for texturing or polishing the surfaces of monocrystalline silicon wafers using an anisotropic etching process with aqueous solutions containing hydrofluoric acid (HF), hydrochloric acid (HCl), and selected oxidizing agents, or using HF with gaseous chlorine. The process is effective at near-room temperatures, uses less toxic and easily available materials, and allows for both cleaning and surface modification in a single step. It can generate desirable surface morphologies, such as square-based pyramids, suitable for applications like solar cells, and is effective irrespective of the wafer cutting method.

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• Manufacturing high-efficiency monocrystalline silicon solar cells with anti-reflective textured surfaces.
• Polishing and cleaning silicon wafers for semiconductor device fabrication.
• Inline processing of silicon wafers for photovoltaic or microelectronic industries.
• Processing silicon wafers cut by different methods (e.g., diamond-wire-sawn, SiC-slurry-sawn) to obtain uniform surface textures.
• Reduction of steps in wafer surface preparation by combining cleaning, texturing, and polishing.

BenefitsContent extracted from patent full text and abstract with AI.

• Enables the use of economical, easily accessible, and less toxic chemicals.
• Achieves efficient etching at or near room temperature, reducing energy consumption.
• Simultaneously cleans and textures or polishes the silicon wafer surface, saving process steps and time.
• Reduces the emission of toxic gases and minimizes wastewater production compared to traditional methods.
• Yields higher etching (removal) rates than standard alkaline solutions, allowing for faster and potentially inline manufacturing.
• Applicable to wafers prepared by various cutting techniques with comparable results.

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Inventors & Applicants

Patent Abstract

The invention relates to a method for producing textures or polishes on the surface of monocrystalline silicon wafers by means of anisotropic etching processes. The problem addressed by the invention is that of developing a method for producing textures or polishes on the surface of monocrystalline silicon wafers in which economical, easily accessible, non-toxic raw materials can be used, which can be performed near room temperature in an energy-saving manner, in which the cleaning and the texturing or polishing of the wafer surface occur simultaneously, in which less toxic exhaust gases are released and smaller amounts of waste water are produced, by means of which a higher removal rate than with the use of alkaline solutions can be achieved such that in-line processing is possible, and which produces comparable textures on both SiC-slurry-sawed silicon wafers and diamond-wire-sawed silicon wafers. Surprisingly, it was found that pyramids having a square base are produced when aqueous mixtures of hydrofluoric acid (HF), hydrochloric acid (HCl), and an added oxidant or aqueous solutions of hydrofluoric acid (HF) and fed chlorine (Cl2) are used as etching solutions in the treatment of monocrystalline silicon (100) wafers. Ammonium peroxodisulfate ((NH4)2S2O8), sodium peroxodisulfate (Na2S2O8), hydrogen peroxide (H2O2), potassium permanganate (KMnO4), ozone (O3), and nitric acid (HNO3) were preferably used as oxidants.