AVS 49th International Symposium
    Dielectrics Thursday Sessions
       Session DI+EL-ThM

Paper DI+EL-ThM8
Hafnium Oxide As an Alternative Gate Dielectric in MOSCAP and MOSFET Application

Thursday, November 7, 2002, 10:40 am, Room C-107

Session: Issues for Gate Dielectrics
Presenter: Y. Lin, University of California, Los Angeles
Authors: Y. Lin, University of California, Los Angeles
R. Puthenkovilakam, University of California, Los Angeles
J.P. Chang, University of California, Los Angeles
Correspondent: Click to Email
HfO@sub 2@ is investigated in this study to replace SiO@sub 2@ as the gate dielectric material in metal-oxide-semiconductor devices. HfO@sub 2@ films were deposited on P-type Si (100) wafers by an atomic layer chemical vapor deposition (AL-CVD) process using hafnium (IV) t-butoxide Hf(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 and uniform based on X-ray photoemission spectroscopic and ellipsometry. The X-ray diffraction analysis indicated the deposited film was amorphous, however, it showed an interfacial layer formation at on the silicon substrate based on the chemical etching resistance experiment. This interfacial layer will be examined by the high-resolution transmission electron and medium energy ion scattering analysis. The step coverage will also be examined by depositing HfO@sub 2@ on 200 nm features with an aspect ratio of 4. The thermal stability of HfO@sub 2@ thin film on silicon was examined by Synchrotron radiation x-ray photoemission spectroscopy. The HfO@sub 2@ thin films were thermally stable up to 950° C in vacuum. In-situ Infrared analysis and ellipsometer measurement are underway to enhance our ability to understand the surface reactions. Isotope labeling of oxygen will be perform to study the effect of the oxidation/annealing processes on film composition. The dielectric constant of HfO@sub 2@ was 18 from the C-V measurement, which was slightly lower than the bulk HfO@sub 2@ . In the C-V measurement a small hysteresis and the interface state density was approximately 5.22x10@super 11@ cm@super -2@ eV@super -1@ are observed. The leakage current is 2~3 order magnitude lower than SiO@sub 2@ at the same equivalent oxide thickness. NMOS transistors will be fabricating to exam the applicability of HfO@sub 2@ for MOSFET application.