Patent ID: 9324843
Filing Date: 2016-04-26
CPC Classification: H01L

Claim Text:
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: 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 Si