MOSFETs comprising source/drain regions with slanted upper surfaces, and method for fabricating the same

摘要

The present invention relates to improved metal-oxide-semiconductor field effect transistor (MOSFET) devices comprising source and drain (S/D) regions having slanted upper surfaces with respect to a substrate surface. Such S/D regions may comprise semiconductor structures that are epitaxially grown in surface recesses in a semiconductor substrate. The surface recesses preferable each has a bottom surface that is parallel to the substrate surface, which is oriented along one of a first set of equivalent crystal planes, and one or more sidewall surfaces that are oriented along a second, different set of equivalent crystal planes. The slanted upper surfaces of the S/D regions function to improve the stress profile in the channel region as well as to reduce contact resistance of the MOSFET. Such S/D regions with slanted upper surfaces can be readily formed by crystallographic etching of the semiconductor substrate, followed by epitaxial growth of a semiconductor material.