Selective Wet and Dry Etching of Hydrogenated Amorphous Silicon and Related Materials

The etch rate in aqueous KOH solutions and in CF4-O2 plasmas was measured for hydrogenated amorphous silicon (a-Si) as a function of preparation conditions, and was compared to that of silicon in the hydrogen-free amorphous, polycrystalline, and crystalline form. The rate depends strongly on hydrogen content in wet etching and moderately in plasma etching. In analogy to crystalline silicon, the plasma etch rate of a-Si exhibits a strong dependence on the Fermi level. © 1988, The Electrochemical Society, Inc. All rights reserved.