Nanocutting Mechanism Of Silicon Carbide Investigated By Stress-assisted And Ion-implant-assisted Approaches

Single crystal silicon carbide is a typical third-generation semiconductor material,with its physical characteristics such as high breakdown voltage and high thermal conductivity,which are superior to traditional silicon.So single crystal silicon carbide is widely used in the research and development of electronic sensor devices with the characteristics of high temperature,high pressure,high frequency,radiation resistance and high power.As a result,it is an indispensable and important material in aviation,military,nuclear energy and civil advanced technology.However,due to the high hardness and brittleness of silicon carbide,it brings great challenges to the fabrication of single crystal silicon carbide,which limits the transformation of silicon carbide related research results.Therefore,it has become the focus of research to study the machining mechanism of single crystal silicon carbide to improve its processing technology and to realize high precision and low damage fabrication.In this paper,the nanocutting mechanism,stress-assisted machining mechanism and ion-implantassisted machining mechanism of single crystal 3C-SiC were studied based on molecular dynamics(MD)simulation,aiming at the related problems in the processing of single crystal silicon carbide.The main research contents and conclusions are as follows:(1)The taper cutting model of single crystal silicon carbide with continuous cutting depth was established,and the material removal forms at different stages were analyzed.Negative rake angle could produce necessary hydrostatic stress to achieve ductile removal by the extrusion in ductile regime machining.In ductile-brittle transition,dislocation movement was the main reason for plastic removal of silicon carbide,accompanied by the phenomenon of deformation localization characterized by cleavage.Based on the platform of scanning electron microscope online observation,the nanocutting experiments of 3C-SiC were carried out,and the MD simulation results were verified.(2)Based on molecular dynamics simulation,the effectiveness of the stressassisted machining method to improve the nanocutting performance of silicon carbide was studied.The improvement of cutting performance under different pre-stress was analyzed,and then the research on the mechanism of stress-assisted machining silicon carbide was carried out.It was found that the plastic removal ability of silicon carbide could be enhanced by the application of appropriate pre-stress.(3)MD simulation model of ion-implant-assisted machining silicon carbide was established.It was proved that ion-implant-assisted machining was helpful to improve the critical ductile-brittle transition cutting depth and the manufacturing integrity of nanocutting silicon carbide.