AVS 49th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuA

Paper TF-TuA4
ZrO@sub2@ Thin Film Growth by CVD from Tetrakis-diethylamino-zirconium for High-k Gate Dielectrics

Tuesday, November 5, 2002, 3:00 pm, Room C-101

Session: Atomic Layer Deposition - Oxides
Presenter: I. Nishinaka, University of Tokyo, Japan
Authors: I. Nishinaka, University of Tokyo, Japan
T. Kawamoto, University of Tokyo, Japan
Y. Shimogaki, University of Tokyo, Japan
Correspondent: Click to Email
In order to improve the performance of ULSI, the scale of MOS (Metal-Oxide-Semiconductor) transistor tends to be reduced. Gate dielectric scaling will require new insulating materials with high dielectric constants to provide increased capacitance without increasing the gate leakage current by direct tunneling. ZrO@sub2@ films were investigated as high-k gate insulators for possible gate dielectric applications. We employed tubular CVD reactor system to investigate the kinetics of ZrO@sub2@-CVD from tetrakis-diethylamio-zirconium (TDEAZ) as zirconium source. The growth rate profile in the tubular reactor strogly indicated that TDEAZ directly deposited on the surface and the decomposition of TDEAZ by gas phase reaction did not occur. The step coverage was constant independent of the substrate position, and the sticking probability at 340°C estimated from the step coverage profile by Monte Carlo simulations was 0.004. The as deposited film structure was amorphous at 300-340°C. As the films were subjected to the rapid thermal oxidation, the film structure changed amorphous into monoclinic and then into amorphous again by increasing the annealing temperature. This structural change resulted from the decrease of the residual nitrogen and carbon, and the increase of the silicon that diffused from the substrate into the ZrO@sub2@ films. After annealing at 1000°C, Si concentration in the film was about 40%, and Zr was 10%. The initial growth process of CVD by TDEAZ was investigated by changing the deoposition time, and surface coverages of Zr and Si were examined using XPS. The time dependencies of XPS signal intensities of these elements revealed that the ZrO@sub2@ film growth from TDEAZ is not island-like growth, but is layer-by-layer growth. This initial growth behavior may be applicable to ALD (Atomic Layer Deposition).