The Mechanical Properties Of Polycrystalline Silicon Carbide Films Determined Using Bulk Micromachined Diaphragms

摘要

This paper reports the determination of the Young's modulus and residual stress of polycrystalline silicon carbide (polySiC) thin films grown on as-deposited (610℃) and annealed (1280℃) polycrystalline silicon (polysilicon) substrates. These mechanical properties are determined by applying an interferometric load-deflection technique to suspended polySiC diaphragms that are fabricated by bulk micromachining. Data analysis of the load-deflection measurements reveals that the average Young's modulus of polySiC grown on as-deposited polysilicon is -350 Gpa, while the corresponding value for polySiC grown on annealed polysilicon is -460 Gpa. Furthermore, the residual stress of polySiC films is similar for both as-deposited and annealed polysilicon substrates at 440 Mpa (tensile). The relatively lower value of Young's modulus of polySiC films grown on as-deposited polysilicon is attributed to its highly textured, columnar-like grain microstructure.