Numerical Study On Micro-nano Processing Of Three-body Abrasive Grains Of Hard And Brittle Materials Based On Molecular Dynamics

Silicon(Si)wafers are widely used in the construction of integrated circuits in the semiconductor industry.With the application of large-scale and ultra-large-scale integrated devices,there is an urgent need for Si wafers of larger size and thinner thickness,so that high output and good performance of integrated circuits can be expected.In order to achieve high cost efficiency in wafer processing,fine polishing or grinding systems,many researchers have studied it.Ultra-precision abrasive polishing is a modern ultra-precision mechanical removal technology based on the nanometer scale.This requires very strict processing technology,experimental environment,and ultra-precision machining of machine tools,making experimental processing difficult.However,molecular dynamics simulation methods can meet these requirements.As a computer calculation method,molecular dynamics simulation has become a very reliable tool for studying the detection and analysis of processing mechanisms of various materials on the nanometer scale.In the nano-machining process of single-crystal silicon,in order to study factors such as material processing effect,resource loss,tool wear,dislocation nucleation and emission,crack formation and propagation mechanism,this article carried out three-body abrasive particles by establishing a three-dimensional MD model Nanoindentation single crystal silicon,three-body abrasive particles polished single-crystal silicon under graphene lubrication,and structured abrasive particles three-body polished single-crystal silicon.The main work of the thesis is as follows:(1)For the first time,a large-scale MD simulation was carried out using abrasive grain nanoindentation single crystal silicon with different rotation angular velocities,and the changes of stress,temperature and potential energy in the nanoindentation area were analyzed.In addition,we also conducted a detailed numerical analysis of the t hree-body diamond abrasive nanoindentation single crystal silicon atoms by studying dislocations,workpiece coordination number,defect atoms,and loading.The study in this chapter aims to reveal the changes and trends in the physical quantities of nano-indented single crystal silicon by studying the rotation speed of the abrasive particles.(2)For the first time,discuss the coordination number of silicon atoms in the workpiece by abrasive grains with different polishing speeds / depths,surface morphology during processing,damage degree of subsurface layer,friction coefficient,and stress,temperature,potential energy in the polishing area with polishing Change in distance.It is tried to find that the changes of the two variables,polishing depth and speed,on the above-mentioned physical quantities finally explain the super-lubricating effect of single-layer graphene on three-body polished single-crystal silicon.(3)The first study of ultra-precision mechanical three-body polishing and revealed the mechanism of nano-structured diamond abrasive particles polishing the surface.In order to clarify the advantages and disadvantages of nanostructured abrasive particles,the phase transformation process of workpiece atoms,dislocations,structured abrasive particles and unstructured abrasive particles in the nano-polishing algorithm(DXA),surface morphology,atomic displacement,temperature distribution and polishing The calculation results such as force are discussed.