US Patent 10008568 Structure and formation method of semiconductor device structure

Structures and formation methods of a semiconductor device structure are provided. The semiconductor device structure includes a gate stack over a semiconductor substrate. The semiconductor device structure also includes a source/drain structure over the semiconductor substrate, and the source/drain structure includes a dopant. The semiconductor device structure further includes a channel region under the gate stack. In addition, the semiconductor device structure includes a semiconductor layer surrounding the source/drain structure. The semiconductor layer is configured to prevent the dopant from entering the channel region.