A semiconductor device includes a substrate, first and second isolation layers, an insulation layer pattern, and a gate structure. The substrate has a cell region and a peripheral region. The first isolation layer is buried in a first upper portion of the substrate in the peripheral region. The second isolation layer is buried in a second upper portion of the substrate in the cell region, and extends along a first direction substantially parallel to a top surface of the substrate. The insulation layer pattern is buried in the first upper portion, and extends along a second direction substantially parallel to the top surface of the substrate and substantially perpendicular to the first direction. The insulation layer pattern has a lower surface higher than a lower surface of the second isolation layer, and applies a stress to a portion of the substrate adjacent thereto.