Experimental Study Of Fracture Strength Of Microscale 3C-SiC By Cantilever Bending Test

SiC,widely regarded as high temperature semiconductor material,drew more and more attention in the field of MEMS devices operating under high temperature.At present,the research on the mechanical properties of micro scale SiC has achieved some progress,but there is still lack of a unified mechanical parameters standard,especially for the temperature characteristics at high temperature.In this paper,micro scale 3C-SiC material fracture strength is measured by bending test under high temperature.Scale effect of cantilever fracture is studied.Residual stress in 3C-SiC film is measured by measuring profile of cantilevers and Raman shift.The specific contents include the following:1.In the aspects of experiment designing,microcantilever bending test is designed based on the operation principle of NanoTest Xtreme and FT-MTA02 micromechanical testing system.The scale of microcantilever is designed and a method of calculating fracture strength is presented.2.In the aspects of sample preparation,a 2.4?m thick 3C-SiC thin film is fabricated using a chemical vapor deposition(CVD)on Si(100)and microcantilevers are fabricated by removing the film's supporting substrate using ICP etcher.In order to analyse error of fracture strength,residual stress is measured.The mean residual stress is-57 MPa and the gradient residual stress is-175 MPa.3.In the aspects of experiment measurement and analysis,bending strength of microcantilevers at different sizes are measured by FT-MTA02 at room temperature,and the Weibull average strength is 1550.58MPa-2106.20 MPa.Bending strength of microcantilevers at different sizes are measured by NanoTest Xtreme at different temperatures and the Weibull average strength is 1144.87MPa-1929.09 MPa.Size effect on Weibull average fracture strength of microscale 3C-SiC is discovered.Moreover it is discovered that fracture strength of microscale 3C-SiC decreasing significantly around 750?.