AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA8
Silicon Etching using Large Diameter Neutral Beam Source

Wednesday, October 20, 2010, 4:20 pm, Room Galisteo

Session: Neutral Beam Processing
Presenter: T. Kubota, BEANS Project 3D BEANS Center and University of Tokyo, Japan
Authors: T. Kubota, BEANS Project 3D BEANS Center and University of Tokyo, Japan
S. Ueki, BEANS Project 3D BEANS Center, Japan
O. Nukaga, BEANS Project 3D BEANS Center and University of Tokyo, Japan
M. Sugiyama, BEANS Project 3D BEANS Center and University of Tokyo, Japan
H. Ohtake, Tohoku University, Japan
S. Samukawa, BEANS Project 3D BEANS Center and Tohoku University, Japan
Correspondent: Click to Email
Plasma etching is widely used for fabricating semiconductor electronic devices, microelectomechanical systems (MEMS), but plasma etching is known to cause damages due to the charge-up and UV irradiation. To overcome plasma-induced damages, neutral beam is widely studied by several groups in the world. Samukawa proposed a neutral beam source using negative ions in plasma and carbon aperture plate for neutralization [S. Samukawa, K. Sakamoto, and K. Ichiki, Jpn. J. Appl. Phys., 40, L779 (2001)]. The neutral beam source achieved high neutralization efficiency by using negative ions from pulse-time modulation plasma, and UV irradiation was drastically reduced. To apply this neutral beam source to mass production, we developed a large-diameter neutral beam source by using an 8-inch-diameter inductively coupled plasma etcher (Panasonic Factory Solutions Co., Ltd. E620) as an ion source. We measured flux and energy of neutral particles, ions, and photons and it was revealed that an argon neutral beam flux of more than 1 mA/cm2 in the equivalent current density and a neutralization efficiency of more than 99%. Spatial uniformity of the neutral beam flux was within ±6%. Si etching with vertical profile using an F2-based neutral beam was achieved with a high etch rate of about 100 nm/min. The spatial uniformity of the etch rate was better than ±5%. The etch rate was increased by applying bias power to the neutralization aperture plate, demonstrating that an accelerated neutral beam was successful in operation. This neutral beam source will enable the usage of damage-free neutral beam processes for practical use in the near future. A part of this work was supported by the New Energy and Industrial Technology Development Organization (NEDO). This work is partly supported by Formation of Innovation Center for Fusion of Advanced Technologies, Special Coordination Funds for Promoting Science and Technology, Ministry of Education, Culture, Sports, Science and Technology.