Semiconductor device forming method and structure for retarding dopant-enhanced diffusion

Abstract

Methods and structure formed for retarding diffusion of a dopant into a channel of a strained Si—SiGe CMOS device are disclosed. The methods form a diffusion retardant region in a substrate including at least one diffusion retardant species such as xenon (Xe), and then form a channel layer over the diffusion retardant region. Each step is conducted prior to formation of a gate on the substrate. As a result, if necessary, the diffusion retardant region can be annealed and cleaned or etched to remove defects in the substrate to reduce external resistance and leakage of devices. The diffusion retardant region positioned under the channel slows down the diffusion of a dopant, e.g., arsenic (As). The invention is also applicable to other substrates.

Dependencies are inferred from the claim text.