A kind of silicon etchant for removing grain

Abstract

The invention relates to a silicon etchant for removing grain. The etching solution is composed of nitric acid, hydroxylamine nitrate, fluorosulfonic acid, ammonium bifluoride, xenon difluoride, sulfuric acid, thickener and deionized water. Wherein the thickener can be any one of polyacrylamide, hexanol, octanol, polyethylene glycol, polyvinylpyrrolidone, etc. In the present invention, hydroxylammonium nitrate reacts with fluorosulfonic acid to generate hydrofluoric acid, and xenon difluoride slowly decomposes to generate hydrofluoric acid in an acidic environment, all of which increase the concentration of hydrofluoric acid in the etching solution composition, and can inhibit the combination of the above etching solutions. The time-dependent change of the material maintains a stable etching rate. The anti-grinding etchant of the present invention can be directly used in the roughening process of the back of the abrasive disc to etch away the deep mechanical grains, omitting the polishing and de-grinding process, saving costs, improving production efficiency, and maintaining stability etching life.

Description

technical field [0001] The invention belongs to the cross-technical field of wet electronic chemicals and roughening processing on the back of wafers, and in particular relates to a silicon etchant for removing abrasive grains. Background technique [0002] In the manufacture of integrated circuit chips, it is necessary to inject metal on the back of the silicon chip. This metal layer can be used as a metal layer for electrodes, bonding, and heat conduction, thereby achieving the effect of heat dissipation and reducing resistance. However, the backside of the wafer needs to be roughened before the backside metallization process, otherwise the surface of the silicon wafer is too smooth, it is difficult for metal ions to adhere and stay on the surface, and it is difficult for the metal layer to be closely connected with the substrate, which will lead to peeling of the metal layer and increase in resistance , Affect the reliability of semiconductor devices. There are already s...

AI Technical Summary

Problems solved by technology

Patent Document 1 has a low etching rate and a small amount of removal per unit time. It is only suitable for silicon wafers treated with chemical wafer thinning liquid, and cannot meet the etching requirements for mechanically abrasive wafers with deep grinding lines.

Therefore, Patent Document 2 first uses 10-16% HF, 20-30% HNO 3 ,15%-25% H 2 SO 4 ,14-20%H 3 PO 4 and 20%-30% water etching mixture for damage etching to remove mechanical wear marks; then use 3%-7% HF, 3%-7% HNO 3 , 75%-85% H 2 SO 4 , 5%-15% water etching mixture to make a rough surface, if only the damage etching solution is used to treat the silicon wafer, because the etching rate is too fast and difficult to control, resulting in uneven etching surface and poor stability of the solution, if only using If the above-mentioned etching solution for making rough surfaces is etched, there will still be abrasive lines after etching, so it must go through two processes

In addition, due to the differences in the process equipment for grinding silicon wafers from different manufacturers, some silicon wafers have deep grinding lines. Wafer thinning fluid is used for mechanical grinding, such a lengthy and complicated process will increase the cost of manufacturing

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