Atomic layer controlled deposition of silicon nitride and in situ growth observation by infrared reflection absorption spectroscopy

We have previously reported that silicon nitride films can be grown by repetitive plasma nitridation of Si using a NH3 remote-plasma and deposition of Si by a SiH2Cl2 thermal reaction. For this process, the deposition rate is self-limited at nearly half-molecular-layer (ML) per one deposition cycle. In this paper, the growth mechanism of the atomic layer deposition (ALD) of silicon nitride has been investigated by in situ Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS). The AFM observation showed that the surface microroughness of the ALD grown silicon nitride film on the thermal CVD Si3N4 is very large, which suggests the islands growth. On the other hand, the roughness is almost maintained after the growth on the hydrogen terminated Si and SiO2 substrates. These results are explained taking account the surface hydrogen atoms. Furthermore, in order to reduce the ion energy of the NH3 plasma, the effect of the magnetic field is investigated.