Etching characteristics of hydrogenated amorphous carbon with different sp2/sp3 hybridization ratios in CF4/O2 plasmas. Issue 11 (26th August 2021)

• Record Type: Journal Article
• Authors: Li, Jie; Kim, Sun J.; Han, Seunghun; Kim, Yongjae; Chae, Heeyeop
• Is Part Of: Plasma processes and polymers. Volume 18:Issue 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-26
• Subjects: CF4/O2 plasma -- hydrogenated amorphous carbon -- plasma etching -- sp2/sp3 hybridization ratio -- thin film; Plasma polymerization -- Periodicals; Plasma-enhanced chemical vapor deposition -- Periodicals; Plasma chemistry -- Periodicals
• DOI: 10.1002/ppap.202100075
• Languages: English
• ISSNs: 1612-8850

Abstract

Abstract: Amorphous carbon is used as a hard mask for dielectric etching with a high aspect ratio in the fabrication processes of semiconductor devices. The dependence of the etching characteristics of hydrogenated amorphous carbon (a‐C:H) films on the sp 2 /sp 3 hybridization ratios was studied for CF4 /O2 plasma mixtures. The etch rate of sp 3 ‐rich a‐C:H is 33.7 times higher than that of sp 2 ‐rich a‐C:H in a plasma comprising 50% CF4 and 50% O2. The etch rate of the sp 2 ‐rich a‐C:H exhibits a linear correlation with the ion density of CF4 /O2 plasma, whereas that of the sp 3 ‐rich a‐C:H exhibits a second‐order exponential correlation with O radical density. A combined etch rate model was suggested to explain the etch rates of a‐C:H. Ion‐enhanced etching is identified as the dominant etching mechanism for the sp 2 ‐rich a‐C:H, whereas spontaneous chemical etching is the main reaction mechanism for the sp 3 ‐rich a‐C:H in CF4 /O2 plasmas. Abstract : A combined etch rate model of the ion‐enhanced etching mechanism and spontaneous radical etching was suggested to explain the etch rates of a‐C:H with different sp 2 /sp 3 ratios in CF4 /O2 plasmas. Ion‐enhanced etching is identified as the dominant etching mechanism for sp 2 ‐rich a‐C:H films, while spontaneous chemical etching is the main reaction mechanism for sp 3 ‐rich a‐C:H etching.