Epitaxial channel

Abstract

Some embodiments of the present disclosure relate to an epitaxially grown replacement channel region within a transistor, which mitigates the variations within the channel of the transistor due to fluctuations in the manufacturing processes. The replacement channel region is formed by recessing source/drain and channel regions of the semiconductor substrate, and epitaxially growing a replacement channel region within the recess, which comprises epitaxially growing a lower epitaxial channel region over a bottom surface of the recess, and epitaxially growing an upper epitaxial channel region over a bottom surface of the recess. The lower epitaxial channel region retards dopant back diffusion from the upper epitaxial channel region, resulting in a steep retrograde dopant profile within the replacement channel region. The upper epitaxial channel region increases carrier mobility within the channel. The replacement channel region provides improved drive current, thereby enabling better performance and higher yield.