FINFET FIN FIELD EFFECT TRANSISTOR FINFET DEVICE STRUCTURE AND METHOD FOR FORMING THE SAME

摘要

A semiconductor device structure and a forming method thereof are provided. A fin field effect transistor (FinFET) device structure includes: a fin structure formed over a substrate; and a gate structure traversing over the fin structure. The gate structure includes a gate electrode layer which includes: an upper portion above the fin structure; and a lower portion below the fin structure. The upper portion has an upper end surface having a first width, and the lower portion has a lower end surface having a second width, wherein the first width is wider than the second width.