Low-pressure chemical vapour deposition growth of epitaxial silicon selective to silicon nitride

The selective epitaxial growth of silicon through windows in a masking material has a wide range of applications for silicon based heterostructures. For many device structures, silicon deposition selective to silicon nitride is required. A novel low-pressure chemical vapour deposition growth process has been developed for epitaxial silicon growth which is selective to silicon nitride. The influence of pressure on the epitaxial quality was investigated. Substrate wafers were heated using a resistive graphite element at 850 °C. The gas chemistry consisted of a combination of SiH4 and SiH2Cl2 in a carrier gas stream of H2 in the ratio 5:1:20, respectively. Selective growth has been demonstrated at pressures from 50 mTorr to 2 Torr on 4 in. wafers, which were patterned with a series of silicon nitride bars.