Study of silicon nitride deposition in III-N MOVPE reactors

•Si3N4 deposition from SiH4 and NH3 in III-N MOVPE reactors is studied.•Si3N4 deposition rate rises with temperature up to 1050–1100 °C.•Under any studied conditions Si3N4 deposition rate is linear with SiH4 concentration.•The higher the pressure is, the faster the Si3N4 deposition is.•Under H2 ambient deposition rate rapidly rises with NH3 flow and then gradually falls. Si3N4 deposition from silane and ammonia in a number of III-N MOVPE reactors of various sizes was studied in a wide range of reactor conditions. It was revealed that Si3N4 deposition rate depends on temperature, pressure, carrier gas type, and ammonia concentration. Deposition rate rises with temperature up to 1050–1100 °C in a manner typical for temperature-activated processes, but under any studied conditions, including the 800–850 °C range, it is strictly linear with SiH4 concentration indicating the absence of high-order parasitic reactions at high temperature and surface passivation at low temperature. For a low-volume reactor the higher the pressure is, the faster the deposition is both for N2 and H2 carrier gases. For large reactors the dependence is non-monotonic. At temperature above 900 °C using H2 as a carrier gas results in a higher Si3N4 deposition rate than when using N2. If nitrogen is used as a carrier gas, deposition rate gradually rises with ammonia concentration. If hydrogen is used, deposition rate rapidly rises with ammonia concentration and then gradually falls. If hydrogen-nitrogen mixture is used as a carrier gas, deposition rate changes in a linear manner with the mole fraction of hydrogen in the carrier gas.