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Kinetics of the tungsten hexafluoride-silane reaction for the chemical vapor deposition of tungsten

Thesis/Dissertation ·
OSTI ID:7019704

In this study, the kinetics of the low-pressure chemical vapor deposition (LPCVD) of tungsten by silane reduction of tungsten hexafluoride on Si(100) surfaces was studied. A single-wafer, cold-wall reactor was sued for the experiments. The SiH[sub 4]/WF[sub 6] ratio was 1.0. The pressure and temperature range were 1-10 torr and 137-385[degree]C, respectively. Kinetic data were obtained in the absence of mass-transfer effects. The film thicknesses were measured by gravimetry. Scanning electron microscopy (SEM), Auger electron spectroscopy (AES), x-ray diffraction (XRD), and resistivity measurements were used to analyze the W films. For the horizontal substrate position and 4-minute reaction times, the apparent activation energies were determined to be 0.35 eV/atom for 10 torr, 0.17 eV/atom for 3 torr, and 0.08 eV/atom for 1 torr. Lower temperatures and higher pressures produced porous films, while higher temperatures and lower pressures resulted in continuous films with smoother surfaces. As the Si-W interface, a W(110) preferential orientation was observed. As the W films grew thicker, W orientation switched from (110) to (100). Apparent activation energy seems to change with thickness.

Research Organization:
Montana State Univ., Bozeman, MT (United States)
OSTI ID:
7019704
Country of Publication:
United States
Language:
English