IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Dielectrics Monday Sessions
       Session DI-MoA

Paper DI-MoA3
High Dielectric Constant Material as an Alternative Gate Dielectric in MOSCAP and MOSFET Applications

Monday, October 29, 2001, 2:40 pm, Room 130

Session: High K Dielectrics I
Presenter: Y.S. Lin, University of California, Los Angeles
Authors: Y.S. Lin, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
ZrO@sub 2@ is investigated in this study to replace SiO@sub 2@ as the gate dielectric material in metal-oxide-semiconductor devices. ZrO@sub 2@ films were deposited on P-type Si (100) wafers by a rapid thermal chemical vapor deposition process using Zr(OC@sub 4@H@sub 9@)@sub 4@ as the precursor and oxygen as the oxidant. The two chemistries were introduced sequentially into the reactor with purging and evacuation in between. The deposited films were stoichiometric, uniform and extremely smooth based on X-ray photoemission, ellipsometry, and atomic force microscopy measurements. The high-resolution transmission electron micrograph showed a polycrystalline ZrO@sub 2@ film (monoclinic) and an interfacial amorphous ZrSi@sub x@O@sub y@ layer on the silicon substrate. This interfacial layer is confirmed to be zirconium silicate based on the thermodynamic calculation, chemical etching resistance, and medium energy ion scattering analysis. Excellent step coverage was observed by depositing ZrO@sub 2@ over 300 nm features with an aspect ratio of 4. The conformal deposition profile can be simulated by the Monte Carlo method with a sticking coefficient on the order of 10@super -4@. In-situ transmission infrared analysis is used to examine the chemically absorbed surface species during the deposition process with various chemical exposures. Isotope labeling of oxygen is underway to assess the effect of the oxidation/annealing processes on film composition and electrical performance. The dielectric constant of RT-CVD ZrO@sub 2@ was 15-18, and the capacitance-voltage measurement showed a hysteresis around 100 mV, which was slightly higher than desired <45 mV value. The interface state density was ~ 1.2x10@super 11@ cm@super -2@eV@super -1@, as determined by capacitance measure at various frequencies. NMOS transistors are made with n@super +@ polysilicon gate, and good turn-on characteristic and low leakage current density of 2x10@super -7@ A/cm@super 2@ at - 1.5V were observed.