Formation of a channel semiconductor alloy by forming a hard mask layer stack and applying a plasma-based mask patterning process

Abstract

When forming sophisticated high-k metal gate electrode structures, a threshold adjusting semiconductor alloy may be formed on the basis of selective epitaxial growth techniques and a hard mask comprising at least two hard mask layers. The hard mask may be patterned on the basis of a plasma-based etch process, thereby providing superior uniformity during the further processing upon depositing the threshold adjusting semiconductor material. In some illustrative embodiments, one hard mask layer is removed prior to actually selectively depositing the threshold adjusting semiconductor material.