Structures and formation methods of a semiconductor device structure are provided. The semiconductor device structure includes a fin structure over a semiconductor substrate. The fin structure includes a first surface and a second surface. The first surface is inclined to the second surface. The semiconductor device structure also includes a passivation layer covering the first surface and the second surface of the fin structure. The thickness of a first portion of the passivation layer covering the first surface is substantially the same as that of a second portion of the passivation layer covering the second surface.