Process for etching N, P, N+ and P+ type slugs and wafers

Abstract

A process for etching single crystal silicon semiconductor material of the N, P, N+ and P+ type slugs and wafers to delineate slip, lineage, dislocation, S-pit, twins, swirl and oxidation induced stacking fault defects involves the steps of: a) preparing a substantially metal-free etchant bath comprising nitric acid (70%), hydrofluoric acid (49%) and between approximately 35% to 98% by weight of glacial acetic acid (HAc) as a diluent, the minimum useful concentration of nitric acid being % Nitric acid.sub.min. =16.67›1-(% HAc/100)! and the maximum useful concentration of nitric acid being % Nitric acid.sub.max. =66.67›1-(% HAc/100)!, the minimum useful concentration of hydrofluoric acid being % HF.sub.min. =100%-% HAc % HNO.sub.3 max. and the maximum useful concentration of hydrofluoric acid being % HF.sub.max. -100%-% HAc-HNO.sub.2min. b) activating the etchant bath by generating NO.sub.x therein and allowing the temperature of the bath to rise to approximately 25.degree. to 34.degree. C.; c) brining the semiconductor material in a clean and damage-free condition into contact with the bath maintained at the said temperature; d) agitating the bath by bubbling an inert gas therethrough and maintaining the semiconductor material in contact with the resultant agitated bath and for a period of time sufficient to remove at least approximately 0.5 micron of silicon therefrom; and e) quenching the resultant etching of the semiconductor material by rinsing with water.

Dependencies are inferred from the claim text.