Integrated circuit semiconductor devices including a metal oxide semiconductor (mos) transistor

Abstract

A semiconductor device includes a first region having a first active pattern with first protrusion portions and first recess portions, and a second region having a second active pattern with second protrusion portions and second recess portions. First gate patterns are on the first protrusion portions. Second gate patterns are on the second protrusion portions. A first source/drain region is on one of the first recess portion of the first active pattern between two of the first gate patterns. The first source/drain region has a first reinforcing epitaxial layer at an upper portion thereof. A second source/drain region is on one of the second recess portions of the second active pattern between two of the second gate patterns. The second source/drain region has a second reinforcing epitaxial layer having an epitaxial growth surface that is shaped differently than a first epitaxial growth surface of the first reinforcing epitaxial layer.