US Patent 11670681 Method of forming fully strained channels

A method includes forming an N well and a P well in a substrate; depositing a first layer having silicon over the N well and the P well; depositing a first dielectric layer over the first layer; forming a resist pattern over the first dielectric layer, the resist pattern providing an opening directly above the N well; etching the first dielectric layer and the first layer through the opening, leaving a first portion of the first layer over the N well; removing the resist pattern; and epitaxially growing a second layer having silicon germanium (SiGe) over the first portion of the first layer. The epitaxially growing the second layer includes steps of (a) performing a baking process, (b) depositing a silicon seed layer, and (c) depositing a SiGe layer over the silicon seed layer, wherein the steps (a), (b), and (c) are performed under about a same temperature.