Deposition of Phosphorus Doped Silicon Films by Thermal Decomposition of Disilane

Abstract

Phosphorus doped silicon films are deposited in the temperature range 520–665°C by thermal decomposition of Si₂H₆. It is found that (i) the deposition rate is not decreased by the addition of PH₃ in contrast with the deposition rate for the SiH₄ system and is about 100 times higher than that for the SiH₄ system for phosphorus concentration above 1×10²⁰ cm^-3, (ii) phosphorus concentration is proportional to the PH₃ partial pressure and to the –3/2 power of Si₂H₆ partial pressure. These characteristics mean that Si₂H₆ is suitable as a source gas to prepare the heavily phosphorus doped polycrystalline silicon for fabricating gate or emitter electrodes of LSI's.