SEMICONDUCTOR DEVICE

A semiconductor device includes peripheral active patterns on a substrate, first and second peripheral trench regions adjacent the peripheral active patterns, a first isolation liner on inner surfaces of the first and second peripheral trench regions, a second isolation liner on the first isolation liner in the first and second peripheral trench regions, and a device isolation layer on the second isolation liner in the first and second peripheral trench regions. The device isolation layer includes a seam therein in the second peripheral trench region. A width of the first peripheral trench region is greater than a width of the second peripheral trench region at a first height corresponding to top surfaces of the peripheral active patterns with respect to the substrate.