Structure and method for highly strained germanium channel fins for high mobility pfinfets

Abstract

A method is provided that includes providing a material stack of, from bottom to top, a relaxed and n-type doped silicon germanium alloy layer and a relaxed silicon germanium alloy layer, each layer having a uniform germanium content, on a surface of a relaxed and graded silicon germanium alloy buffer layer that is located within a pFET device region of a semiconductor substrate. Next, the relaxed silicon germanium alloy layer is patterned to provide at least one relaxed silicon germanium alloy fin having the uniform germanium content on the relaxed and n-type doped silicon germanium alloy layer. A strained germanium layer is then formed surrounding the at least one relaxed silicon germanium alloy fin. A portion of the strained germanium layer and the at least one relaxed silicon germanium alloy fin can be used as composited channel material for fabricating a pFinFET device.