Initial stage of semiinsulating polycrystalline silicon film growth

An experimental investigation is conducted into the initial stage of deposition for semiinsulating polycrystalline silicon (SIPOS) versus undoped polycrystalline silicon, with the N2O-to-SiH4 flow-rate ratios ranging from 0 to 0.23. It is shown that adding N2O to SiH4 does not change the pattern of the process. The initial stage is found to consist of a period of island growth followed by a period of coalescence, ending with the formation of a continuous film. Islands arise with a horizontal size of up to 95 nm. The minimum thickness of a continuous film is about 5 nm for SIPOS as against 22 ± 4 nm for undoped polycrystalline silicon.