US Patent 6900094 Method of selective removal of SiGe alloys

A method is disclosed of forming buried channel devices and surface channel devices on a heterostructure semiconductor substrate. In an embodiment, the method includes the steps of providing a structure including a first layer having a first oxidation rate disposed over a second layer having a second oxidation rate wherein the first oxidation rate is greater than the second oxidation rate, reacting said first layer to form a sacrificial layer, and removing said sacrificial layer to expose said second layer.