High germanium content silicon germanium fins

摘要

Thermal condensation is employed to obtain a finned structure including strained silicon germanium fins having vertical side walls and a germanium content that may be high relative to silicon. A hard mask is used directly on a low-germanium content silicon germanium layer. The hard mask is patterned and fins are formed beneath the hard mask from the silicon germanium layer. Thermal condensation in an oxidizing ambient causes the formation of regions beneath the hard mask that have a high germanium content. The hard mask is trimmed to a target critical dimension. The regions beneath the hard mask and adjoining oxide material are subjected to reactive ion etch, resulting in the formation of high-germanium content fins with planar, vertically extending sidewalls.

主权项

1. A method comprising:
obtaining a structure comprising a silicon germanium layer having a first germanium concentration and an electrically insulating layer adjoining the silicon germanium layer, the structure being obtained by:
obtaining a silicon-on-insulator structure including a substrate layer, a silicon layer, and the electrically insulating layer;forming an epitaxial silicon germanium layer on the silicon layer;causing thermal condensation in an oxidizing ambient of the epitaxial silicon germanium layer, thereby forming the silicon germanium layer on the electrically insulating layer and an oxide layer on the silicon germanium layer, andremoving the oxide layer; forming a hard mask on the silicon germanium layer; patterning the hard mask; forming a silicon germanium first fin from a portion of the silicon germanium layer beneath the patterned hard mask; causing thermal condensation in an oxidizing ambient of the silicon germanium first fin to form a germanium-containing region beneath the patterned hard mask having a second germanium concentration higher than the first germanium concentration and an oxide region adjoining the germanium-containing region; trimming the patterned hard mask, thereby forming a hard mask fin adjoining the germanium-containing region having a target critical dimension; removing the oxide region adjoining the germanium-containing region, and anisotropically etching the germanium-containing region down to or within the electrically insulating layer, thereby forming a germanium-containing second fin having the target critical dimension and planar, vertically extending sidewalls, the entirety of the second fin further consisting essentially of Si1-yGey where y is greater than 0.75.