Interdiffusion barrier layer is formed for a silicon and silicon-germanium composite gate e.g. of a CMOS device

摘要

A silicon and germanium interdiffusion barrier layer, for a silicon and silicon-germanium composite gate, is formed by nitriding and/or oxidizing a silicon film deposited on the silicon-germanium layer (4) before deposition of the gate silicon layer (7). A layer, for restricting silicon and germanium interdiffusion between a Si1-xGex (x = greater than 0 to 1) layer (4) and a silicon encapsulation layer (7) of a semiconductor device gate, is formed, before deposition of the silicon encapsulation layer, by depositing an amorphous or polycrystalline silicon thin film on the Si1-xGex layer (4) and either (a) treating the silicon layer with gaseous nitric oxide at 450-600 deg C and 103-105 Pa to obtain a nitrided silicon thin film (6); or (b) oxidizing the silicon layer to form a less than 1 nm thick silicon oxide surface film (6) and then optionally carrying out step (a).