US Patent 9786774 Metal gate of gate-all-around transistor

The disclosure relates to a semiconductor device. An exemplary structure for a semiconductor device comprises a nanowire structure comprising a channel region between a source region and a drain region; and a metal gate surrounding a portion the channel region, wherein the metal gate comprising a first gate portion adjacent to the source region having a first thickness and a second gate portion adjacent to the drain region having a second thickness less than the first thickness.