|AVS 54th International Symposium|
|Plasma Science and Technology||Tuesday Sessions|
|Session:||Plasma Etching for Advanced Interconnects II|
|Presenter:||E. Soda, Selete, Japan|
|Authors:||E. Soda, Selete, Japan
S. Kondo, Selete, Japan
Y. Ichihashi, Tohoku University, Japan
A. Sato, Tohoku University, Japan
H. Ohtake, Tohoku University, Japan
S. Samukawa, Tohoku University, Japan
S. Saito, Selete, Japan
|Correspondent:||Click to Email|
The CF3I gas has been developed to reduce the recent global warming1 because it has a low global warming potential (GWP) of 1.0 while most of conventional etching gases have considerably higher potentials of more than 1000 (CF4: 6500, C4F8: 8700). The feasibility of CF3I plasma etching and its damage to the porous low-k film (SiOC, k=2.6) were studied in this work. When an SiOC film was exposed to the CF3I plasma, increase in the k-value and decrease in CH3 group of the film (FTIR) were found to be suppressed compared with those caused by conventional CF4 plasma because intensity of the ultra violet (UV) light in CF3I plasma was lower than that of CF4 plasma. To investigate etching property of CF3I gas, we used a photolithography patterned wafer with the resist mask of 200-nm pitch size. As a result, the etching profile of CF3I plasma was comparable with that of CF4 plasma. Since the etching selectivity (SiOC/ArF) of CF3I plasma was higher than that of CF4 plasma, the remaining resist thickness after etching increased, thereby line edge roughness (LER) was suppressed. Moreover, the pulse operation in CF3I plasma drastically increased etching rate and minimized UV damage to the low-k film because injection of negative ions in pulsed plasma enhanced the low-k film etching. Accordingly, we found that CF3I plasma is one of the promising candidates for low-damage and highly selective low-k etching. This work is supported by the New Energy and Industrial Technology Development Organization (NEDO).
1N. Nagasaki et al., "The Development of a Novel Catalytic Technology for CF3I Manufacture", Halon Options Technical Working Conference, May 2000.