US 12,002,854 B2
Semiconductor device and method of manufacture
Heng-Wen Ting, Pingtung (TW); Kei-Wei Chen, Tainan (TW); Chii-Horng Li, Zhubei (TW); Pei-Ren Jeng, Chu-Bei (TW); Hsueh-Chang Sung, Zhubei (TW); Yen-Ru Lee, Hsinchu (TW); and Chun-An Lin, Tainan (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Nov. 8, 2021, as Appl. No. 17/520,983.
Application 17/520,983 is a division of application No. 16/548,430, filed on Aug. 22, 2019, granted, now 11,171,209.
Claims priority of provisional application 62/737,698, filed on Sep. 27, 2018.
Prior Publication US 2022/0059655 A1, Feb. 24, 2022
Int. Cl. H01L 29/08 (2006.01); H01L 21/02 (2006.01); H01L 29/66 (2006.01); H01L 29/78 (2006.01)
CPC H01L 29/0847 (2013.01) [H01L 21/02532 (2013.01); H01L 29/66545 (2013.01); H01L 29/6681 (2013.01); H01L 29/785 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A device comprising:
a fin extending from a substrate;
a gate stack over the fin;
a source/drain region in the fin adjacent the gate stack, the source/drain region comprising:
a first source/drain layer having a germanium concentration of that is lower than 40 atomic percent and having a thickness of less than 10 nm;
a second source/drain layer over the first source/drain layer, the second source/drain layer having a germanium concentration of 40 to 50 atomic percent and having a thickness that is less than 25 nm;
a third source/drain layer over the second source/drain layer, the third source/drain layer having a germanium concentration of 60 to 80 atomic percent;
a fourth source/drain layer over the third source/drain layer, the fourth source/drain layer having a germanium concentration that is less than 40 atomic percent, wherein each of the first source/drain layer, the second source/drain layer, the third source/drain layer and the fourth source/drain layer comprise facets, and wherein a topmost point of the first source/drain layer is lower than a bottommost point of the third source/drain layer and a bottommost point of the fourth source/drain layer; and
a source/drain contact contacting the source/drain region.