Patent ID: 11923409
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  B | IPC H

Claim 6:
7. A device, comprising:
a semiconductor substrate,
a first semiconductor layer above the semiconductor substrate and extending in parallel to the semiconductor substrate;
a second semiconductor layer above the first semiconductor layer and extending in parallel to the first semiconductor layer
a third semiconductor layer above the second semiconductor layer and extending in parallel to the second semiconductor layer;
a gate structure having a first gate portion vertically between the semiconductor substrate and the first semiconductor layer, a second gate portion vertically between the first semiconductor layer and the second semiconductor layer, and a third gate portion vertically between the second semiconductor layer and the third semiconductor layer;
a source/drain feature connected to the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer;
a first spacer between the source/drain feature and the first gate portion;
a second spacer between source/drain feature and the second gate portion; and
a third spacer between the source/drain feature and the third gate portion,
wherein the source/drain feature has a first curved surface exposed in a first air gap between the first spacer and the source/drain feature, a second curved surface exposed in a second air gap between the second spacer and the source/drain feature, and a third curved surface exposed in a third air gap between the third spacer and the source/drain feature,
wherein the first curved surface includes an apex at a mid-height of the first air gap, the second curved surface includes an apex at a mid-height of the second air gap, and the third curved surface includes an apex at a mid-height of the third air gap, wherein the third curved surface has a greater curvature than the second curved surface, and the second curved surface has a greater curvature than the first curved surface,
wherein portions of the source/drain feature extend laterally such that the portions of the source/drain feature are vertically between the first and the second spacers and between the second and the third spacers.