SURFACE-MORPHOLOGY OF P-TYPE (100)SILICON ETCHED IN AQUEOUS ALKALINE-SOLUTION

We report on a study of the morphology of (100) silicon surfaces etche d in aqueous alkaline solutions. It is shown that the formation of pyr amidal hillocks during etching can be influenced in two different ways : by the presence of an oxidizing agent (ferricyanide or oxygen) in th e etchant solution, or by etching under anodic bias. In both cases pyr amid formation is suppressed without a significant change of the etch rate. The addition of ferricyanide does not markedly change the etchin g anisotropy. The formation, stability, and suppression of the pyramid s are discussed.