METHOD OF PREVENTING EPITAXY CREEPING UNDER THE SPACER

摘要

After forming a gate spacer on each sidewall of a sacrificial gate structure, portions of each dielectric fin cap portion underneath the gate spacer is intentionally etched and undercut regions that are formed are filled and pinched off with a dielectric material of a conformal dielectric liner. Portions of the conformal dielectric liner in the undercut regions are not subject to the undercut during an epitaxial pre-clean process performed prior to forming an epitaxial source region and an epitaxial drain region on opposite sides of the sacrificial gate structure and remain in the undercut regions after forming the epitaxial source region and the epitaxial drain region.

主权项

1. A method of forming a semiconductor structure comprising:
etching a semiconductor substrate to form a plurality of fin structures, each of the plurality of the fin structures having a dielectric fin cap atop the fin structure; forming a sacrificial gate structure over the dielectric fin caps; forming a gate spacer on each sidewall of the sacrificial gate structure; forming a dielectric fin cap portion by removing portions of each of the dielectric fin caps that are not covered by the sacrificial gate structure or the gate spacer; laterally etching each of the dielectric fin cap portions to provide an undercut region underneath each gate spacer; forming a dielectric liner portion within each of the undercut regions; forming an epitaxial source region and an epitaxial drain region on portions of the fin structures that are not covered by the sacrificial gate structure, the gate spacers and the dielectric liner portions; removing the sacrificial gate structure to expose remaining portions of the dielectric fin cap portions; and removing the remaining portions of the dielectric fin cap portions to form a gate cavity, wherein the dielectric liner portions remain in the undercut regions during said forming the epitaxial source region and the epitaxial drain region.