Patent ID: 11862709
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  B | IPC H

Claim 9:
10. A method, comprising:
receiving a substrate;
forming a first semiconductor layer over the substrate;
forming a second semiconductor layer having a first region over the first semiconductor layer, a second region over the first region, and a third region over the second region, the first region and the third region each include a first germanium concentration, and the second region includes a second germanium concentration smaller than the first germanium concentration;
forming a third semiconductor layer over the second semiconductor layer;
forming a source/drain trench extending through the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer;
laterally and selectively etching the second semiconductor layer to form an opening between an end portion of the first semiconductor layer and an end portion of the third semiconductor layer, the opening having a first interface with the etched second semiconductor layer;
forming a spacer in the opening; and
forming a source/drain feature in the source/drain trench.