Analysis of Polymer Formation during SiO 2 Microwave Plasma Etching

• Published in: Japanese Journal of Applied Physics Vol. 34; no. 4S; p. 2132
• Main Authors: Gotoh, Yasushi, Tokuo Kure, Tokuo Kure
• Format: Journal Article
• Language: English
• Published: 01.04.1995
• DOI: 10.1143/JJAP.34.2132
• ISSN: 0021-4922

The mechanism of C x F y fluorocarbon deposition during SiO 2 etching is analyzed using a test sample with an overhang mask. For C 4 F 8 , CHF 3 , and CH 2 F 2 , only C x F y deposition was observed at 0 W of substrate-bias rf power, and the deposition profiles were similar. At a higher rf power, reaction phenomena changed to those of SiO 2 etching. The standard deviation σ of the etching-ion incident angle was measured as less than 2°. On the other hand, σ d e p o measured from the deposition profile was about 20°. This difference may be caused by surface migration. This migration is thought to be a key factor in excess deposition at the bottom of a high-aspect-ratio hole. Etching rates of the deposit increased in the order of C 4 F 8 >CHF 3 >CH 2 F 2 . Therefore, SiO 2 -etching gases, such as C 4 F 8 , which form easily removable deposits, reduce RIE lags for contact hole patterning.