Improvement of process parameters for polycrystalline silicon carbide low pressure chemical vapor deposition on 150Â mm silicon substrate using monomethylsilane as precursor

This work shows a systematic approach using design of experiments (DoE) for the integration of the deposition process for polycrystalline 3C-SiC from 100 mm to 150 mm wafers in a vertical low pressure chemical vapor deposition furnace. The approach aims at developing n-doped SiC thin films on silicon substrates with low stress and low resistivity showing high uniformity of growth rate across boat and wafer. The 3C-SiC films are prepared using monomethylsilane (MMS) as the main precursor, dichlorosilane (DCS) as an additional Si source, ammonia (NH3) as dopant and hydrogen (H2) as diluting gas. The experimental parameters are temperature, pressure, DCS flow and NH3 flow. Flow rates of MMS and H2 are kept constant, resulting in a two factorial DoE approach of 16 experiments. The analyzed response parameters are thickness, stress, and resistivity, including the thickness uniformity across boat and wafer. A strong influence of NH3 (dopant) is found on the deposition rate, resistivity and stress of the film. Increasing the NH3 flow from 1 to 2 sccm leads to a decrease in the deposition rate by a factor of three. The improved 3C-SiC film with the intended parameters obtained within the experiments showed a resistivity as low as 75 mΩ cm and a low stress of 306 MPa with the lowest deposition temperature of 775 °C.