Patent ID: 11929409
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 17:
18. A method for forming a semiconductor device structure, comprising:
forming a first source/drain feature in a first region of a substrate, comprising:
forming a first epitaxial layer with a first dopant concentration;
forming a second epitaxial layer with a second dopant concentration on the first epitaxial layer, wherein the second epitaxial layer has a first cross-sectional profile; and
forming a third epitaxial layer with a third dopant concentration on the second epitaxial layer, wherein the third epitaxial layer has a first center portion and a first edge portion that has a height higher than the first center portion, and the third dopant concentration is greater than the second dopant concentration, and the second dopant concentration is greater than the first dopant concentration;

forming a second source/drain feature in the first region of the substrate, comprising:
forming a first epitaxial layer with a fourth dopant concentration;
forming a second epitaxial layer with a fifth dopant concentration on the first epitaxial layer of the second source/drain feature, wherein the second epitaxial layer of the second source/drain feature has a second cross-sectional profile that is substantially identical to the first cross-sectional profile; and
forming a third epitaxial layer with a sixth dopant concentration on the second epitaxial layer, wherein the third epitaxial layer has a second center portion and a second edge portion that has a height higher than the second center portion of the third epitaxial layer of the second source/drain feature, and the sixth dopant concentration is greater than the fifth dopant concentration, and the fifth dopant concentration is greater than the fourth dopant concentration;

forming a contact etch stop layer over the third epitaxial layer of the first and second source/drain features;
forming an interlayer dielectric on the contact etch stop layer;
forming a source/drain contact through the interlayer dielectric and the contact etch stop layer, the source/drain contact being in contact with at least a portion of the third epitaxial layer of the first and second source/drain features; and
forming a third source/drain feature in a second region of the substrate, comprising:
forming a first epitaxial layer with a seventh dopant concentration;
forming a second epitaxial layer with an eighth dopant concentration on the first epitaxial layer of the second source/drain feature, wherein the second epitaxial layer of the second source/drain feature has a third cross-sectional profile that is different than the first cross-sectional profile; and
forming a third epitaxial layer with a ninth dopant concentration on the second epitaxial layer, wherein the ninth dopant concentration is greater than the eighth dopant concentration, and the eighth dopant concentration is greater than the seventh dopant concentration.