A method of forming a semiconductor device having first and second fin structures on a substrate includes forming a first epitaxial region of the first fin structure and forming a second epitaxial region of the second fin structure. The method further includes forming a buffer region on the first epitaxial region of the first fin structure and performing an etch process to etch back a portion of the second epitaxial region. The buffer region helps to prevents etch back of a top surface of the first epitaxial region during the etch process. Further, a capping region is formed on the buffer region and the etched second epitaxial region.