AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoM

Paper PS2-MoM5
Highly Anisotropic and Damage-free Gate Electrode Patterning in Neutral Beam Etching Using F@sub 2@ Based Gas Chemistry

Monday, November 15, 2004, 9:40 am, Room 213B

Session: Silicon Etching
Presenter: S. Noda, Tohoku University, Japan
Authors: S. Noda, Tohoku University, Japan
Y. Hoshino, Showa Denko K.K., Japan
T. Ozaki, Tohoku University, Japan
S. Samukawa, Tohoku University, Japan
Correspondent: Click to Email
Neutral beam etching is a promising candidate for the damage-free processing of semiconductor devices. To realize high-performance etching processes, we developed a new neutral beam etching system. In this system, highly efficient neutral beams could be obtained by accelerating negative ions generated in the pulse-time-modulated plasma. Damage-free 50 nm poly-Si gate electrode patterning has already been accomplished by our system using the Cl@sub 2@/SF@sub 6@ mixture gas chemistry@footnote 1@. In this gas chemistry, accelerated Cl and F atoms contributed to the etching reaction and the etching profiles were controlled by changing the gas flow ratio. However, the etching rate and the pattern profile were drastically varied with changing the gas flow ratio. Especially, by increasing the SF@sub 6@ flow rate, both the etching rate and the side etching increased rapidly. There were trade-off between the etching rate and etching profile in the SF@sub 6@ based gas chemistry. Namely, SF@sub 6@ plasma generated a large amount of F radicals. To settle this problem, F@sub 2@ gas plasma was investigated to generate the fast F atom beam efficiently with maintaining low density of F radical. In comparison between F@sub 2@ and SF@sub 6@, great differences were observed in the etching characteristics. Even in the case of pure F@sub 2@ gas chemistry, the etching anisotropy drastically increased and the side etching of poly-Si hardly occurred. It is caused by elimination of the F radical generation and increase of negative ion (F@super -@) generation in the F@sub 2@ plasma. Using this feature, more flexible and precise control will be achieved in the neutral beam etching method. @FootnoteText@ S. Noda et al., to be published in J. Vac. Sci. and Technol. A, Jul/Aug (2004).