A method of forming a semiconductor device, and a product formed thereby, is provided. The method includes forming a pattern in a mask layer using, for example, double patterning or multi-patterning techniques. The mask is treated to smooth or round sharp corners. In an embodiment in which a positive pattern is formed in the mask, the treatment may comprise a plasma process or an isotropic wet etch. In an embodiment in which a negative pattern is formed in the mask, the treatment may comprise formation of conformal layer over the mask pattern. The conformal layer will have the effect of rounding the sharp corners. Other techniques may be used to smooth or round the corners of the mask.