Etching solution for silicon wafer

Abstract

The invention discloses an etching solution for a silicon wafer. The etching solution is mainly prepared from electronic-grade nitric acid, electronic-grade hydrofluoric acid, electronic-grade sulfuric acid, electronic-grade phosphoric acid, electronic-grade acetic acid, a surfactant and ultrapure water, wherein the nitric acid serves as an oxidizing agent and can oxidize silicon into silicon oxide, the hydrofluoric acid serves as a dissolving agent and can dissolve and remove the silicon oxide so as to realize etching of the silicon wafer, the sulfuric acid can improve the viscosity of the solution, stabilize the reaction rate, not change the etching morphology and improve the etching uniformity, the phosphoric acid can also improve the viscosity of the solution, improve the mass transferresistance, decrease the etching rate and not change the etching morphology, the acetic acid serves as a diluent and can reduce the ionization degree of the nitric acid, inhibit the oxidation capacity of the nitric acid, decrease the reaction rate and influence the surface morphology after etching, and the surfactant can reduce the surface tension of the solution and improve the surface morphology of the etched silicon wafer. The etching solution has the advantages of being stable and controllable in etching rate and uniform and flat in etching surface.

Description

technical field [0001] The invention relates to an etching solution in the manufacturing process of silicon wafers, which satisfies the design and manufacturing requirements of semiconductor chips by chemically treating the surface of the silicon wafers. Background technique [0002] Semiconductor silicon wafer manufacturing is a multi-stage manufacturing process. The processing of ingots into silicon wafers requires processes such as cutting, chamfering, grinding, corrosion, and polishing. In the silicon wafer processing process, the quality output of subsequent processes It may be related to the manufacturing defects of the previous process, and even some quality problems will always be inherited by many subsequent processes, and finally flow to the client. [0003] Silicon wafers used in the semiconductor industry need to have good flatness and low surface defects, but the silicon wafers obtained after cutting and grinding often have poor flatness and mechanical processin...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, it is difficult to control the etching rate and surface by using nitric acid and hydrofluoric acid systems, and it is necessary to add other components to improve the performance of the etching solution

For example, Patent Document 1 adopts two-step wet etching to thin the back of the wafer. First, the silicon substrate is etched with a mixture of hydrofluoric acid, nitric acid, phosphoric acid and sulfuric acid to expose the epitaxial layer, and then hydrofluoric acid, nitric acid The silicon substrate and the exposed epitaxial layer are selectively etched with a mixture of acetic acid and ultra-thin and uniform wafers, but the two-step wet etching adds processing steps and is more complicated to operate

Patent Document 2 uses a mixed solution of nitric acid, hydrofluoric acid, and sulfuric acid to etch a silicon substrate, but this etching solution helps to roughen the surface of the silicon substrate, and a surface with good flatness cannot be obtained