Alkaline etching solution for semiconductor wafers and alkaline etching method
View Patent ↗Alkaline etching solutions capable of improving a surface roughness even with a relatively low alkaline concentration, contain bromate or both bromate and nitrate. An alkaline etching method using the solution produces silicon wafers with improved surface roughness.
1. A method of etching a silicon wafer with an alkaline solution, comprising etching the silicon wafer with a caustic alkaline aqueous solution containing bromate and nitrate.
2. The method of claim 1 , wherein the bromate is sodium bromate.
3. The method of claim 1 , wherein the nitrate is sodium nitrate.
4. A method of manufacturing a silicon wafer, comprising the step of etching the semiconductor silicon wafer by the method of claim 1 , wherein the wafer after etching has a surface roughness Ra equal to or smaller than 0.27 μm.
5. The method of claim 1 , wherein the caustic alkaline aqueous solution comprises an alkali hydroxide in a concentration of 20-60% by weight.
6. The method of claim 5 , wherein the caustic alkaline aqueous solution comprises an alkali hydroxide in a concentration of 45-50% by weight.
7. The method of claim 1 , wherein the concentration of the bromate is 0.01 to 10% by weight.
8. The method of claim 1 , wherein the concentration of the nitrate is 0.01 to 10% by weight.
9. The method of claim 1 , wherein the nitrate and the bromate are present in equimolar amounts.