A method for forming a pattern of a semiconductor device and a semiconductor device formed using the same are provided. The method includes forming a buffer layer on a substrate, forming a channel layer on the buffer layer, forming support patterns penetrating the channel layer, and forming channel fin patterns and a buffer pattern by patterning the channel layer and the buffer layer. The channel layer includes a material of which a lattice constant is different from that of the buffer layer, and each of the channel fin patterns has both sidewalls that are in contact with the support patterns and are opposite to each other.