Molecular Dynamics Simulation Of The Process In The Chemical Mechanical Polishing Of Cubic Silicon Carbide

Silicon carbide(SiC)is a atomic crystal,which is the third generation of semiconductor materials and has developed rapidly in recent years.Silicon carbide has many properties such as large band gap,high thermal conductivity,high breakdown field strength,low dielectric constant and strong anti radiation.It is widly used in the field of MEMS,high energy semiconductor devices etc.The great hardness of silicon carbide makes it difficult to be processed,chemical mechanical polishing(CMP)is the only method to realize global planarization at present.The cutting depth of CMP is nanometer or sub nanometer.Because of the size effect,the traditional cutting theory can not explain the change of material surface in CMP process very well.Molecular dynamics(MD)simulation technology is the ideal research methods to explore the microscopic mechanism and atomic scale process with its high spatial resolution.The MD simulation is widely used in the field of tribology,nanomechanics and crystallography.Firstly,establish an atomic model composed of a diamond abrasive particle and cubic silicon carbide substrate.CMP will be simplified to the process of the embedded abrasive particle scratching on the workpiece.The changes of material morphology,crystal structure,temperature,cutting force and potential energy can be obtained at the atomic level with the method of MD simulation.Adjust the polishing parameters,such as scratching velocity,scratching depth and abrasive size to analyze the changes in macroscopic quantities.Extract the number of atoms above the workpiece surface to analyze the removal rate,and summarize the way to improve the removal rate and the quality of the surface of the material.Secondly,consider the influence of different external factors on the process of CMP.Establish an atomic model with SiC layer for substrate and amorphous silica layer for surface to simulate the effect of oxide film in the scratching process and compare the change of temperature,force and the Material deformation mechanism.Study the effect of ultrasonic vibration in the process of CMP by imposing a harmonic vibration to the abrasive.Analyze the influence of vibration frequency and amplitude variation on tangential force,normal force,and the workpiece surface.The influence of relaxation phenomenon on potential energy and surface quality is analyzed.Finally,nano-indentation,nano-scratch and macroscopic scratch experiments are studied to obtain the relationship among the depth,load and friction.Combine with the results at various scales,the simulation results are proved.