US 11,894,435 B2
Contact plug structure of semiconductor device and method of forming same
Pei-Yu Chou, Hsinchu (TW); Jr-Hung Li, Chupei (TW); and Tze-Liang Lee, Hsinchu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Mar. 5, 2021, as Appl. No. 17/193,626.
Claims priority of provisional application 63/091,971, filed on Oct. 15, 2020.
Prior Publication US 2022/0123115 A1, Apr. 21, 2022
Int. Cl. H01L 29/417 (2006.01); H01L 23/535 (2006.01); H01L 29/40 (2006.01); H01L 29/78 (2006.01); H01L 21/768 (2006.01)
CPC H01L 29/41791 (2013.01) [H01L 21/76832 (2013.01); H01L 21/76897 (2013.01); H01L 23/535 (2013.01); H01L 29/401 (2013.01); H01L 29/7851 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
forming a gate stack over a substrate;
recessing the gate stack to form a first recess;
forming a cap layer over the gate stack in the first recess, the cap layer comprising a first material over the gate stack and a second material over the first material, the second material being different from the first material, wherein forming the cap layer comprises:
filling the first recess with the first material; and
performing an oxygen addition process on an upper portion of the first material, the oxygen addition process converting the upper portion of the first material into the second material;
forming a first conductive feature adjacent the gate stack; and
forming a second conductive feature over the first conductive feature, the second conductive feature being in physical contact with a topmost surface of the cap layer and a topmost surface of the first conductive feature.