AVS 50th International Symposium
    High-k Gate Dielectrics and Devices Topical Conference Tuesday Sessions
       Session DI-TuP

Paper DI-TuP5
NH@sub 3@ Nitridation Effect on HfO@sub 2@-Al@sub 2@O@sub 3@ Films in the MOS Capacitor

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: C. Lee, Seoul National University, Korea
Authors: C. Lee, Seoul National University, Korea
J. Choi, Seoul National University, Korea
M. Cho, Seoul National University, Korea
C.S. Hwang, Seoul National University, Korea
H.J. Kim, Seoul National University, Korea
Correspondent: Click to Email
High-k gate dielectrics, such as HfO@sub 2@ and Al@sub 2@O@sub 3@, have been investigated as an alternative to SiO@sub 2@ for low power device due to high dielectric constant, thermodynamic compatibility of the interface with Si substrate, and a relatively large band gap. We investigated the nitrogen diffusion behavior and electrical characteristics, especially flat band voltage (V@sub fb@) shift and V@sub fb@ hysteresis by NH@sub 3@ nitridation of the MOS capacitors. The nitrided MOS capacitors include the various high-k gate dielectric stacks such as Pt gate/HfO@sub 2@/p-type Si, Pt gate/HfO@sub 2@-Al@sub 2@O@sub 3@/p-type Si, and Pt gate/capping Al@sub 2@O@sub 3@-HfO@sub 2@-Al@sub 2@O@sub 3@/p-type Si. HfO@sub 2@ and Al@sub 2@O@sub 3@ films were deposited on p-type epitaxial Si (100) wafers with a resistivity of 1 @ohm@cm by atomic layer deposition (ALD) technique using HfCl@sub 4@, Al(CH@sub 3@)@sub 3@ and H@sub 2@O at 300°C after RCA SC1 and HF cleaning. Post deposition annealing (PDA) of the samples was performed with rapid thermal annealing (RTA) at 700°C, 800°C, and 900°C in NH@sub 3@ for 30 seconds. Post-metallization annealing (PMA) of Pt-top electrodes was performed at 400°C for 30 min. under a 5% H@sub 2@ + 95% N@sub 2@ atmosphere. V@sub fb@ shifted negatively with increasing nitridation temperature, but it moved positively with increasing Al@sub 2@O@sub 3@ thickness. HfO@sub 2@-Al@sub 2@O@sub 3@ film showed excellent V@sub fb@ shift and hysteresis characteristics when it was post-metallization annealed in NH@sub 3@ at 800°C for 30 seconds. NH@sub 3@ nitridation effect on Pt gate/HfO@sub 2@-Al@sub 2@O@sub 3@/p-type Si MOS capacitors with increasing PDA temperature was analyzed by electrical evaluation, Auger Electron Spectroscopy (AES), atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM).