Bulk fin formation with vertical fin sidewall profile

摘要

Fabricating a semiconductor device includes providing a substrate, wherein the substrate is comprised of a base layer, a doped silicon layer on top of the base layer, and an undoped silicon layer on top of the doped silicon layer; forming a hard mask layer on top of the substrate; forming at least one mandrel on top of the hard mask layer; forming a spacer layer on top of exposed portions of the hard mask layer and the at least one mandrel; etching portions of the spacer layer; removing the at least one mandrel; etching regions of the hard mask layer and the undoped silicon layer not protected by remaining portions of the spacer layer to form at least one fin; and removing the remaining portions of the spacer layer.