Selective Molybdenum Deposition by LPCVD.

Molybdenum films have been deposited by Low Pressure Chemical Vapor Deposition (LPCVD) on patterned silicon substrates by the reduction of molybdenum hexafluoride in hydrogen and argon atmospheres. The deposition is extremely selective, with no presence of Mo observed on silicon dioxide surfaces over the temperature range 200-400C. The Mo deposition rates have been studied as a function of the reactive gas flow rates, the temperature, the nature of the ambient and the doping of Si substrate. Reduction by both hydrogen and silicon contribute to the deposition, with approximately equal, extremely high deposition rates. It is found that the resultant film thickness is proportional to the deposition time up to a thickness of 7microns; no self- timing thickness was observed.