METHOD FOR FORMING SILICON-GERMANIUM EPITAXIAL LAYER

摘要

A method for forming a SiGe epitaxial layer is described. A first SEG process is performed under a first condition, consuming about 1% to 20% of the total process time for forming the SiGe epitaxial layer. Then, a second SEG process is performed under a second condition, consuming about 99% to 80% of the total process time. The first condition and the second condition include different temperatures or pressures. The first and the second SEG processes each uses a reactant gas that includes at least a Si-containing gas and a Ge-containing gas.