Transistor fabrication using double etch/refill process
A semiconductor fabrication process includes forming a gate electrode (120) overlying a gate dielectric (110) overlying a semiconductor substrate (102). First spacers (124) are formed on sidewalls of the gate electrode (120). First s/d trenches (130) are formed in the substrate (102) using the gate electrode (120) and first spacers (124) as a mask. The first s/d trenches (130) are filled with a first s/d structure (132). Second spacers (140) are formed on the gate electrode (120) sidewalls adjacent the first spacers (124). Second s/d trenches (150) are formed in the substrate (102) using the gate electrode (120) and the second spacers (140) as a mask. The second s/d trenches (150) are filled with a second s/d structure (152). Filling the first and second s/d trenches (130, 150) preferably includes growing the s/d structures using an epitaxial process. The s/d structures (132, 152) may be stress inducing structures such as silicon germanium for PMOS transistors and silicon carbon for NMOS transistors.
Freescale Semiconductor, Inc.
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Da Ted R. Bich-Yen Voon-Yew Jing
Zhang White Nguyen Thean Liu