AVS 46th International Symposium
    Thin Films Division Tuesday Sessions
       Session TF-TuM

Paper TF-TuM6
Atomic Layer Deposition of Tungsten and Tungsten Nitride Using Sequential Surface Reactions

Tuesday, October 26, 1999, 10:00 am, Room 615

Session: Advanced Thin Film Formation Chemistry
Presenter: J.W. Klaus, University of Colorado, Boulder
Authors: J.W. Klaus, University of Colorado, Boulder
S.J. Ferro, University of Colorado, Boulder
S.M. George, University of Colorado, Boulder
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The deposition of ultrathin and conformal films on high aspect ratio structures is important for forming conducting layers and diffusion barriers. Thin films of tungsten (W) and tungsten nitride (W@sub 2@N) were deposited with atomic layer control using sequential surface reactions. The tungsten growth was accomplished by separating the binary reaction WF@sub 6@ + Si@sub 2@H@sub 6@ --> W + 2SiHF@sub 3@ + 2H@sub 2@ into two half-reactions. The tungsten nitride growth was performed by dividing the binary reaction 2WF@sub 6@ + NH@sub 3@ --> W@sub 2@N + 3HF + 9/2F@sub 2@ into two half-reactions. Successive exposure to WF@sub 6@ and Si@sub 2@H@sub 6@ (NH@sub 3@) in an ABAB... binary reaction sequence produced W (W@sub 2@N) deposition at substrate temperatures between 425-600 K (600-800K). The W deposition rate was 2.49 Å/AB cycle for WF@sub 6@ and Si@sub 2@H@sub 6@ reactant exposures > 800 L and 1600 L, respectively. The WN deposition rate was 2.55 Å/AB cycle for WF@sub 6@ and NH@sub 3@ reactant exposures > 3000 L and 10,000 L, respectively. Atomic force micrographs of the deposited films on Si(100) were remarkably flat indicating smooth and conformal deposition. These results for W represent the first demonstration of atomic layer deposition of conformal single-element films using sequential surface reactions. Similar surface chemical strategies may facilitate the atomic layer growth of other metals besides tungsten.