A semiconductor device is formed to include a fin structure, a first trench at a first lateral end of the fin, a second trench at a second lateral end of the fin, and a filler filled on a first traverse side of the fin and a second traverse side of the fin. The filler is contained between the first trench and the second trench, and oxidized in-place to cause a stress to be exerted on the first and second traverse sides of the fin, the stress causing the fin to exhibit a tensile strain in a lateral running direction of the fin.