MRR Simulation And Experiment Research For Lapping Process Of SIC Monocrystal Wafers

With the rise of artificial intelligence and cloud computing and other science and technology,semiconductor chips made of SiC monocrystal materials play a more and more important role.They are mainly used in electronic devices,optical devices,aerospace,defense production and other fields.SiC crystal has two characteristics of high hardness and high brittleness.It belongs to difficult to processing materials.Therefore,how to efficiently process the material under the premise of guaranteeing the quality is the main research direction of this material.Lapping as an important precision processing methods,this paper uses diamond lapping paste,lapping SiC monocrystal material.The removal mechanism is diamond abrasive particles as the lapping tool for the crystal surface of the fine cutting and scribing.The Material Removal Rate(MRR)as a breakthrough in the study of processing efficiency,a new MRR mathematical model is established to make the theoretical material removal rate closer to the actual material removal rate,and MRR model contains a number of process parameters,such as lapping pressure,lappign pan speed and hardness,etc..Based on the existing MRR model,in order to improve the SiC monocrystal wafer lapping theory,the processing process of a single abrasive particle is studied according to the contact condition of SiC monocrystal wafer and abrasive particles and the contact state between the abrasive particles and the lapping pan.The lapping process is based on the lapping pressure of the abrasive particles,and the extrusion and embedding stage is carried out,then the carving stage is carried out.A new MRR model of material removal rate in lapping process was established.The new model was simulated by MATLAB,and the influence of process parameters on removal rate was studied.In the process of lapping SiC wafers,when the cutting depth is less than the critical cutting depth,the removal state of SiC monocrystal wafer is shown as the shaping grinding.And the rotation of the lappign pan will cause the abrasive particles to produce centrifugal force,which results in the abrasives to undergo a certain degree of torque and spin.In this paper,a three-dimensional model of the contact between the sphere and the plastic plane is established,and the two cases that sphere under normal load and torque or sphere only under normal load.On this basis,the embedded depth of spherical abrasive particles with or without torque was analyzed.According to the difference of embedded depth,the influence of spin motion and torque on the material removal rate was obtained.The ZYP400 lapping equipment is used as the experimental platform,the experimental research based on the lapping theory and MRR model,and then the experimental results were compared with the existing MRR model and the new MRR model,and finally it is found that the extrusion embedded stage new MRR model is more close to the experimental results than the initial MRR model,and proves the feasibility and superiority of the new model.At the same time,the influence mechanism of the lapping parameters on the material removal rate and the influence on the final surface quality were obtained.The theoretical and experimental research on lapping has made an important basis for the prediction and control of the processing efficiency and surface quality of SiC monocrystal wafer and other brittle materials.It has certain theoretical and reference significance.