Isotropic Etching of n-Si(110) in KOH Solution under Applied Voltage.

Abstract

Isotropic chemical wet etching of n-Si (110) was investigated in KOH solution under applied voltage. It was shown that the isotropic etching was achieved in 32wt% KOH at 110 when an applied voltage to a Si wafer was larger than 0.6V (vs. Pt electrode), while the Si wafer was etched anisotropically without applying voltage. This result shows that the etching property, isotropic or anisotropic, is varied by applying voltage. The etching rates of Si (110) for the isotropic and the anisotropic etching were 0.1m/min and 9m/min, respectively at 110. In addition, the etching rate of the isotropic etching did not depend on the applied voltage when using n-Si. The cause of the isotropic etching in KOH solution was originated from etching through anodic oxide layer formed on the Si surface from a XPS-analysis and a temperature dependence of the etching rate.