US 12,255,102 B2
Methods of forming of inner spacer structure using semiconductor material with variable germanium concentration
Che-Lun Chang, Hsinchu (TW); Jiun-Ming Kuo, Taipei (TW); Ji-Yin Tsai, Hsinchu County (TW); and Yuan-Ching Peng, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Nov. 30, 2023, as Appl. No. 18/524,710.
Application 18/524,710 is a continuation of application No. 17/243,274, filed on Apr. 28, 2021, granted, now 11,862,709.
Prior Publication US 2024/0105814 A1, Mar. 28, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H01L 21/8234 (2006.01); H01L 21/02 (2006.01); H01L 21/306 (2006.01); H01L 29/06 (2006.01); H01L 29/423 (2006.01); H01L 29/49 (2006.01); H01L 29/66 (2006.01); H01L 29/786 (2006.01)
CPC H01L 21/823412 (2013.01) [H01L 21/02532 (2013.01); H01L 21/0259 (2013.01); H01L 21/30604 (2013.01); H01L 21/823431 (2013.01); H01L 21/823468 (2013.01); H01L 29/0665 (2013.01); H01L 29/42392 (2013.01); H01L 29/4908 (2013.01); H01L 29/4983 (2013.01); H01L 29/66545 (2013.01); H01L 29/66553 (2013.01); H01L 29/66636 (2013.01); H01L 29/66742 (2013.01); H01L 29/66795 (2013.01); H01L 29/78618 (2013.01); H01L 29/78696 (2013.01)] 20 Claims
OG exemplary drawing
 
17. A method, comprising:
forming over a substrate a stack that comprises a plurality of first layers interleaved by a plurality of second layers;
patterning the stack to form a fin-shaped structure comprising a channel region and a source/drain region;
forming a dummy gate stack over the channel region of the fin-shaped structure;
etching the source/drain region of the fin-shaped structure to form a source/drain trench that exposes sidewalls of the plurality of first layer and the plurality of second layers;
selectively and partially etching the sidewalls of the plurality of second layers to form inner spacer recesses;
forming inner spacer features in the inner spacer recesses; and
after the forming of the inner spacer features, forming a source/drain feature in the source/drain trench,
wherein each of the plurality of second layers comprises:
a bottom sublayer,
a middle sublayer over the bottom sublayer, and
a top sublayer over the middle sublayer,
wherein a first germanium (Ge) concentration in the middle sublayer is lower than a second germanium (Ge) concentration of the bottom sublayer or the top sublayer,
wherein the bottom sublayer comprises a first thickness,
wherein the middle sublayer comprises a second thickness,
wherein the top sublayer comprises a third thickness,
wherein the second thickness is greater than the first thickness or the third thickness.