Patent ID: 11908922
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. A method comprising:
forming a mask layer over a substrate;
patterning the mask layer to expose portions of the substrate;
etching the substrate by using the patterned mask layer as an etch mask to form a plurality of pyramid protrusions at a top surface of the substrate, wherein a top surface of one of the plurality of pyramid protrusions has a (100) crystal orientation;
removing the patterned mask layer;
forming a first epitaxial layer over and in contact with the plurality of pyramid protrusions of the substrate, wherein the first epitaxial layer is a single piece of continuous material;
forming a second epitaxial layer over the first epitaxial layer, wherein the second epitaxial layer is a single piece of continuous material, and the first epitaxial layer is in contact with the substrate and the second epitaxial layer; and
forming a transistor over and partially embedded in the second epitaxial layer.