US 12,131,946 B2
Method to form contacts with multiple depth by enhanced CESL
Min-Hwa Chi, Qingdao (CN); Zhaosheng Meng, Qingdao (CN); and Xian Zhang, Qingdao (CN)
Assigned to SiEn (QingDao) Integrated Circuits Co., Ltd., Qingdao (CN)
Filed by SiEn (QingDao) Integrated Circuits Co., Ltd., Shandong (CN)
Filed on Jan. 25, 2022, as Appl. No. 17/584,210.
Claims priority of application No. 202110140864.3 (CN), filed on Feb. 2, 2021.
Prior Publication US 2022/0246470 A1, Aug. 4, 2022
Int. Cl. H01L 21/768 (2006.01); H01L 21/311 (2006.01); H01L 29/40 (2006.01)
CPC H01L 21/76877 (2013.01) [H01L 21/31133 (2013.01); H01L 21/31138 (2013.01); H01L 21/76802 (2013.01); H01L 21/76829 (2013.01); H01L 29/401 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of forming contact holes of a CMOS (Complementary Metal-Oxide-Semiconductor) device, comprising steps of:
forming a device layer on a substrate, the device layer comprising a gate and an active area, the gate and the active area being positioned on different planes with different depths;
forming an etching stop layer on the gate and the active area;
forming a carbon cap layer on the etching stop layer or forming or a carbon rich layer at a surface of the etching stop layer;
forming an interlayered dielectric layer on the carbon cap layer or the carbon rich layer;
etching the interlayered dielectric layer with at least one etching gas until forming a first part of the contact holes on the etching stop layer, wherein at least one of the first part of the contact holes, which is on the gate, has a depth less than that of at least another one of the first part of the contact holes, which is on the active area, and polymer is formed at a bottom of the at least one of the first part of the contact holes, which is on the gate, when the at least one etching gas acts on the carbon cap layer or the carbon rich layer;
removing the polymer; and
keeping etching the etching stop layer until forming a second part of the contact holes on the gate and the active area, the contact holes comprising the first and second parts of the contact holes.