Patent ID: 11973128
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  B | IPC H

Claim 16:
17. A method, comprising:
providing a workpiece comprising:
a substrate,
a fin-shaped active region over the substrate and including a channel region and a source/drain region, the fin-shaped active region comprising a plurality of channel layers interleaved by a plurality of sacrificial layers, a thickness of each of the plurality of channel layers is greater than a thickness of each of the plurality of sacrificial layers, and
a dummy gate stack over the channel region;

recessing the source/drain region to form a source/drain trench exposing sidewalls of the plurality of channel layers and the plurality of sacrificial layers;
performing an etching process to partially etch the plurality of sacrificial layers, wherein the performing of the etching process further etches the plurality of channel layers to form inner spacer recesses, and upon completion of the performing of the etching process, at least one of the plurality of channel layers includes a tilted top surface and a tilted bottom surface, such that the inner spacer recesses partially extend vertically into the plurality of channel layers;
forming inner spacer features in the inner spacer recesses;
forming a source/drain feature in the source/drain trench;
removing the dummy gate stack to form a gate trench;
selectively removing the plurality of sacrificial layers to form a first plurality of openings in the channel region;
after the selective removing, performing an etching process to trim the plurality of channel layers and enlarge the first plurality of openings; and
forming a gate structure having a first portion in the gate trench and a second portion in the enlarged first plurality of openings, the gate structure comprising a work function layer,
wherein one of the inner spacer features comprises a first sidewall surface in direct contact with the source/drain feature and a second sidewall surface in direct contact with the second portion of the gate structure, wherein the second portion of the gate structure comprises a seam enclosed in the work function layer, and wherein, in a cross-sectional view, a height of the first sidewall surface is greater than a height of the second sidewall surface.