US Patent 9472618 Nanowire field effect transistor device having a replacement gate

One embodiment of the instant disclosure provides a transistor device that comprises: a semiconductor substrate; a buffer layer formed in a fin structure over the semiconductor substrate; a nanowire formed over the buffer layer, having at least a middle portion suspended over the buffer layer by an undercutting, the nanowire including a source and a drain region respectively defined at distal portions thereof and a channel region defined in the suspended portion of the nanowire and connecting the source and drain regions; and a gate structure surrounding at least a portion of the suspended portion of the nanowire.