AVS 52nd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS-MoP

Paper PS-MoP9
Plasma Etching of High-k and Metal Gate Materials in High-Density Chlorine-Containing Plasmas

Monday, October 31, 2005, 5:00 pm, Room Exhibit Hall C&D

Session: Plasma Science and Technology Poster Session
Presenter: K. Nakamura, Kyoto University, Japan
Authors: K. Nakamura, Kyoto University, Japan
T. Kitagawa, Kyoto University, Japan
K. Osari, Kyoto University, Japan
K. Takahashi, Kyoto University, Japan
K. Ono, Kyoto University, Japan
Correspondent: Click to Email
As ultra large scale integrated circuit dimensions continue to be scaled down, high dielectric constant (high-k) materials such as HfO@sub 2@, ZrO@sub 2@, Al@sub 2@O@sub 3@, etc. are being required as gate dielectric to maintain the gate capacitance in smaller size. Moreover, for a gate stack with high-k dielectrics, gate electrodes of conventional polycrystalline silicon (poly-Si) tend to cause some problems of the depletion layer present in doped poly-Si gate materials, thus being replaced by metal electrodes such as Pt, Ru, TaN, TiN etc. For the fabrication of high-k gate stacks, an understanding the etching characteristics and mechanisms is indispensable for high-k dielectrics as well as metal electrodes. However, only a few studies have recently been concerned with their etching for the application to high-k gate stacks. In this study, we have investigated the etching of high-k materials of HfO@sub 2@ and metal electrode materials of Pt and TaN using high-density chlorine-containing plasmas excited by electron cyclotron resonance. The etching of HfO@sub 2@ etching was performed in BCl@sub 3@ plasmas at around 10 mTorr without rf biasing, giving a high etch selectivity (>>1) over Si and SiO@sub 2@ was obtained. At lower pressures, some deposition was found to occur on all material surfaces. The etching of Pt was performed in Ar/O@sub 2@ plasmas with high rf biasing, where highly selective Pt etching was achieved over HfO@sub 2@, Si, and SiO@sub 2@ by adding O@sub 2@ to Ar. Moreover, the etching of TaN was performed in Ar/Cl@sub 2@ plasmas, where high etch rates and high etch selectivity of TaN over HfO@sub 2@, Si and SiO@sub 2@ were obtained with low rf biasing. The etched profiles of Pt and TaN were also investigated; the etched profile of Pt was positive tapered, while the profile of TaN was found to be almost anisotropic. This work was supported by NEDO/MIRAI project and by Taiyo Nippon Sanso Corp.