Morphology control of a silicon nitride thick film derived from polysilazane precursor using UV curing and IR heat treatment

Abstract

Silicon nitride (Si₃N₄) has excellent thermo-mechanical properties, and can be used as heat dissipation substrate for various devices. Si₃N₄ thin films are generally synthesised by chemical vapour deposition (CVD) or plasma-enhanced CVD. The use of polysilazanes (PSZs) as a precursor to the synthesis of Si₃N₄ has attracted significant attention because of their high mouldability and processability. In this study, Si₃N₄ thick films were prepared on silicon wafers or aluminium substrates by a spin- or dip-coating liquid PSZ, followed by UV curing and IR heat treatment under various conditions. The effects of the heat treatment conditions on the Si₃N₄ thick film surface were analysed by optical microscopy, X-ray diffraction, and scanning electron microscopy. An almost single phase of Si₃N₄ was synthesised successfully on the single crystalline silicon with UV curing at 400°C for 30 min and IR heating at 800°C in N₂ atmosphere.