US Patent 9685554 Fin field effect transistor and semiconductor device

A FinFET including a gate stack, a semiconductor fin embedded in the gate stack, a source and a drain disposed is provided. The semiconductor fin extends along a widthwise direction of the gate stack and has a first concave and a second concave exposed at sidewalls of the gate stack respectively. The source and drain are disposed at two opposite sides of the gate stack. The source includes a first ridge portion embedded in the first concave and the drain includes a second ridge portion embedded in the second concave, wherein the first and second ridge portions extend along a height direction of the semiconductor fin.