US 11,942,556 B2
Semiconductor device and manufacturing method thereof
Yu-Ru Lin, Hsinchu (TW); Shu-Han Chen, Hsinchu (TW); Yi-Shao Li, Hsinchu (TW); Chun-Heng Chen, Hsinchu (TW); and Chi On Chui, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed by TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed on Apr. 8, 2021, as Appl. No. 17/225,306.
Prior Publication US 2022/0328698 A1, Oct. 13, 2022
Int. Cl. H01L 29/06 (2006.01); H01L 21/02 (2006.01); H01L 21/3065 (2006.01); H01L 29/417 (2006.01); H01L 29/423 (2006.01); H01L 29/66 (2006.01); H01L 29/786 (2006.01)
CPC H01L 29/78696 (2013.01) [H01L 21/0259 (2013.01); H01L 21/3065 (2013.01); H01L 29/0665 (2013.01); H01L 29/41733 (2013.01); H01L 29/42392 (2013.01); H01L 29/66545 (2013.01); H01L 29/66553 (2013.01); H01L 29/66636 (2013.01); H01L 29/66742 (2013.01); H01L 29/78618 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
forming an epitaxial stack over a substrate, wherein the epitaxial stack comprises a first sacrificial layer, a first channel layer, a second sacrificial layer, and a second channel layer sequentially over the substrate, and a thickness of the first channel layer is greater than a thickness of the second channel layer;
patterning the epitaxial stack to be a fin structure;
forming a dummy gate structure across the fin structure such that the dummy gate structure covers a first portion of the fin structure while second portions of the fin structure are exposed;
removing the exposed second portions of the fin structure;
forming source/drain epitaxial structures on opposite end surfaces of the first and second channel layers in the first portion of the fin structure;
removing the dummy gate structure to expose the first portion of the fin structure;
removing the first and second sacrificial layers in the exposed first portion of the fin structure while leaving the first and second channel layers in the exposed first portion of the fin structure suspended above the substrate;
after removing the first and second sacrificial layers, forming recesses respectively in the first and second channel layers, wherein a depth of the recess in the second channel layer is greater than a depth of the recess in the first channel layer; and
after forming the recesses respectively in the first and second channel layers, forming a gate structure in the recesses to surround each of the suspended first and second channel layers.