AVS 53rd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2+TF-WeM

Paper PS2+TF-WeM3
PECVD Synthesis and Optimization of High @kappa@ Dielectric Structures

Wednesday, November 15, 2006, 8:40 am, Room 2011

Session: Plasma Deposition
Presenter: C.A. Wolden, Colorado School of Mines
Authors: W. Yang, Colorado School of Mines
M. Seman, Colorado School of Mines
C.A. Wolden, Colorado School of Mines
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Alternative dielectrics with high dielectric constants (@kappa@) are required to reduce turn-on voltage and leakage current in conventional as well as thin film transistor technology. The latter application requires processing routes with a low thermal budget. To that end plasma-enhanced chemical vapor deposition processes were developed to fabricate high @kappa@ dielectrics including TiO@sub 2@ and Ta@sub 2@O@sub 5@. The deposition rate was found to be weakly activated, enabling low temperature deposition. The deposition rate was a strong function of the atomic oxygen density, reflecting a competition between plasma-phase oxidation of the precursor and its participation in film growth. Metal-insulator-silicon (MIS) structures were fabricated and characterized using both C-V and I-V measurements. Annealing was found to both enhance @kappa@ and significantly attenuate the leakage current. Under optimized conditions the dielectric performance of MIS devices was superior to that of SiO@sub 2@ control samples with the same equivalent oxide thickness. The leakage current density was correlated to the presence of oxide charge defects in the dielectric, as measured using the flat band voltage shift. By appropriate control of plasma power and oxygen concentration, the flat band voltage shift was minimized and the electrical performance of as-deposited films approached those of annealed samples.