A method of manufacturing a semiconductor device includes forming a plurality of fin structures on a substrate, the plurality of fin structures including a diffusion region, forming an epitaxial layer on the plurality of fin structures in an area of the diffusion region such that a height of the upper surface of the epitaxial layer over plurality of fin structures is substantially equal to the height of the upper surface of the epitaxial layer between the plurality of fin structures, and planarizing the upper surface of the epitaxial layer by one of etch back and reflow annealing.