Silicon etching solution for removing abrasive grains

Abstract

The invention relates to a silicon etching solution for removing abrasive grains. The etching solution is composed of nitric acid, hydroxylamine nitrate, fluorosulfonic acid, ammonium bifluoride, xenon difluoride, sulfuric acid, a thickening agent and deionized water. The thickening agent can be any one of polyacrylamide, hexanol, octanol, polyethylene glycol, polyvinylpyrrolidone and the like. Hydroxylamine nitrate and fluorosulfonic acid react to generate hydrofluoric acid, xenon difluoride is slowly decomposed in an acid environment to generate hydrofluoric acid, the concentration of hydrofluoric acid in the etching liquid composition is increased, the time-dependent change of the etching liquid composition can be inhibited, and the stable etching rate is maintained. The abrasive grainremoving etching solution can be directly used for the back roughening process of an abrasive disc, deep mechanical abrasive grains are etched, the polishing and abrasive grain removing procedure is omitted, the cost is saved, the production efficiency is improved, and meanwhile the stable etching service life can be maintained.

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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