Profile control of isolation structures in semiconductor devices

Abstract

A semiconductor device with doped shallow trench isolation (STI) structures and a method of fabricating the same are disclosed. The method includes forming a fin structure on a substrate, forming a superlattice structure with first and second nanostructured layers arranged in an alternating configuration on the fin structure, depositing an oxide liner surrounding the superlattice structure and the fin structure in a first deposition process, forming a dopant source liner on the oxide liner, depositing an oxide fill layer on the dopant source liner in a second deposition process different from the first deposition process, performing a doping process to form a doped oxide liner and a doped oxide fill layer, removing portions of the doped oxide liner, the doped oxide fill layer, and the dopant source liner from sidewalls of the superlattice structure, and forming a gate structure on the fin structure and surrounding the first nanostructured layers.