Simulation And Experimental Research On Precision Polishing Of Single Crystal Diamond

With the rapid development of semiconductor industry,all kinds of electronic devices are gradually developing in the direction of miniaturization,high temperature resistance,high power and high frequency,etc.As the next generation semiconductor materials,diamond materials with excellent properties have a broader development prospect.In the traditional polishing technology,low efficiency,high cost and poor quality have become important and difficult problems in the field of diamond polishing.Based on the mechanical polishing method,this paper carries out simulation analysis and experimental research on the polishing process of single crystal diamond substrate from both theoretical and experimental aspects.The material surface and subsurface in the polishing process are analyzed by molecular dynamics simulation method,and the influence rules of four groups of process parameters on diamond surface quality are obtained,which can guide the optimization and improvement of polishing process parameters.The single crystal diamond substrate with good surface quality is obtained through experiments.The specific research contents of this paper are as follows:First,the simulation and analysis of polishing single crystal diamond substrate.The polishing system model is established by LAMMPS software,and the suitable potential function,system and integral algorithm are determined.Around the surface and subsurface damage of diamond substrate,the effects of atomic accumulation and amorphous phase transition on materials during polishing are studied by OVITO software.Based on the above simulation model,the effects of different polishing processes(polishing depth,abrasive particle size,polishing speed and polishing pressure)on surface formation and subsurface damage are studied.Through the analysis of the simulation results,it can be concluded that reducing the polishing depth,reducing the abrasive particle size,increasing the polishing speed and reducing the polishing pressure can improve the surface quality of diamond substrate.Through the comparison of the effects of the above polishing process parameters,it is found that the abrasive particle size,polishing depth and polishing pressure have great influence on the polishing process,while the polishing speed has little influence on the material surface removal and subsurface damage.Second,the experiment and analysis of polishing single crystal diamond substrate.The effects of abrasive particle size,polishing time and measuring method on the polishing effect of diamond substrate were obtained by orthogonal polishing experiment.The experimental results show that the variation of diamond substrate surface quality with abrasive particle size is consistent with the simulation results.Through the measurement of the surface roughness of diamond substrate under different polishing time,it is found that the material removal effect is the most obvious in the first ten minutes of polishing,and the surface roughness value decreases greatly,and the polishing efficiency decreases with the increase of polishing time.The efficient polishing of diamond substrate surface can be achieved by using small grain size abrasive,and the surface roughness can be effectively reduced to less than 1nm in the range of 5 μm × 5 μm.When using atomic force microscope for surface testing,the measurement method and the cleanliness of the substrate will affect the measurement results of the substrate;through the Raman spectrometer test,it is found that the surface compressive stress of diamond substrate changes with the decrease of surface roughness.In summary,firstly,the influence of four groups of parameters on the polishing effect is obtained by molecular dynamics simulation.Secondly,the surface roughness of single crystal diamond substrate is lower than that of 1nm by orthogonal polishing experiment.Finally,the measurement of surface residual stress provides an idea for the analysis of surface quality of diamond substrate.