AVS 47th International Symposium
    Dielectrics Wednesday Sessions
       Session DI+EL+MS-WeA

Paper DI+EL+MS-WeA6
Ultra-thin Zirconium Oxide Films Deposited by Rapid Thermal CVD for MOSFET Applications

Wednesday, October 4, 2000, 3:40 pm, Room 312

Session: Alternate Gate Dielectrics
Presenter: Y. Lin, University of California, Los Angeles
Authors: Y. Lin, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
The increasingly tighter process specifications for the next generation microelectronic devices dictate the usage of metal oxides such as zirconium oxide as insulators for better process control and a more reliable dielectric/silicon interface.@footnote 1@ Zirconium t-butoxide is used with O@sub 2@ in this work to deposit zirconium oxide in a RTCVD system. The deposition temperature can be rapidly ramped to and controlled at 400-600°C, and the physical properties of the ZrO@sub 2@ films are characterized by XPS, XRD, AFM, TEM, and spectroscopic ellipsometry to determine the film compositions, chemical states, film microstructures, morphology, thickness, and index of refraction. Amorphous and nearly stoichiometric ZrO@sub 2@ has been deposited with less than 0.2nm variation in thickness across a 4" wafer. The dielectric constant is 3-4 times greater than that of SiO@sub 2@. Leakage current of a ZrO@sub 2@ film with an effective oxide thickness of 10 Å is three orders of magnitude lower than that of a 10Å thermal SiO@sub 2@ film. Post-deposition annealing at 500-700°C is shown to be effective in removing the majority of the incorporated carbon and further reduce the leakage current. However, there exists an optimal carbon doping level where carbon effectively passivates the electrically active defects and reduces the leakage current. We propose a simple kinetic model to describe the heterogeneous reactions responsible for the film deposition. NMOS transistors are fabricated and tested to determine the dielectric constant, leakage current, I-V and C-V characteristics of the zirconium oxide films. Moreover, stress induced leakage current and time dependent dielectric breakdown will also be detailed to assess the material reliability for its applications in microelectronics. @FootnoteText@ @footnote 1@G. D. Wilk, and R. M. Wallace, "Electrical properties of hafnium silicate gate dielectrics deposited directly on silicon," Appl. Phys. Lett., 74(19), 2854(1999).