Chemically vapor deposited tungsten silicide films using dichlorosilane in a single-wafer reactor: Growth, properties, and thermal stability
- Applied Materials, Santa Clara, CA (United States). Applied Conductor Technology Div.
- IBM, Burlington, VT (United States). General Technology Div.
Compositionally uniform (in depth and in lateral position) chemically vapor deposited WSi{sub x} films were deposited on 200 mm Si wafers in a single-wafer in a single-wafer reactor using SiH{sub 2}Cl{sub 2}/WF{sub 6} chemistry. A process window was found to produce highly uniform compositions in the range of 2.2 {le} x {le} 2.6, regardless of the nucleation surface, SiO{sub 2} or poly-Si. 900 C annealing in {sub 2} of such films deposited on P-doped poly-Si resulted in a uniform reduction of x to a value of 2.1 to 2.2. In contrast, as deposited dichlorosilane-WSi{sub x} films which are Si-poor at the interface, were found to develop a high concentration of Si in the middle layer of the annealed structure. The as-deposited resistivity was found to increase linearly with x with a value of {approximately}750 {mu}{Omega} {center_dot} cm for x {approx} 2.5. Upon annealing, the resistivities decreased to values in the range of 80 to 110 {mu}{Omega} {center_dot} cm. The as-deposited films were predominantly in the hexagonal structure of WSi{sub 2}, which transformed to the tetragonal structure upon annealing at temperatures higher than 600 C. As-deposited stresses were in the range of (1.3 to 1.6) {center_dot} 10{sup 10} dyne/cm{sup 2}, and upon annealing reduced to {approximately}1 {center_dot} 10{sup 10} dyne/cm{sup 2}. The films had a very good step coverage even at high aspect ratios and did not crack or peel off upon annealing. The films contained relatively low levels of impurities: F {approximately} 6 {center_dot} 10{sup 16} to 2 {center_dot} 10{sup 17} and Cl {approximately} 5 {center_dot} 10{sup 17} to 1 {center_dot} 10{sup 19} atom/cm{sup 3}. This systematic study reviews the correlations between the structural, compositional, mechanical, and electrical properties of the as-deposited and the annealed silicide films.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 142196
- Journal Information:
- Journal of the Electrochemical Society, Vol. 140, Issue 12; Other Information: PBD: Dec 1993
- Country of Publication:
- United States
- Language:
- English
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