Deposition of Phosphorus Doped Silicon Films by Thermal Decomposition of Disilane

Phosphorus doped silicon films are deposited in the temperature range 520–665°C by thermal decomposition of Si 2 H 6 . It is found that (i) the deposition rate is not decreased by the addition of PH 3 in contrast with the deposition rate for the SiH 4 system and is about 100 times higher than that for the SiH 4 system for phosphorus concentration above 1×10 20 cm -3 , (ii) phosphorus concentration is proportional to the PH 3 partial pressure and to the –3/2 power of Si 2 H 6 partial pressure. These characteristics mean that Si 2 H 6 is suitable as a source gas to prepare the heavily phosphorus doped polycrystalline silicon for fabricating gate or emitter electrodes of LSI's.