A semiconductor device includes a channel layer on a substrate; cell trench patterns in the channel layer; and a source pattern on the cell trench patterns. The source pattern includes: grooves, each having inclined sidewalls and bottom that extends in a horizontal direction in a portion of the channel layer between the cell trench patterns, source regions at the inclined sidewalls of the grooves, source isolation regions at the bottoms of the grooves, and a source electrode at interior regions of the grooves and that has a planar upper surface.