Study On The Formation Mechanism And Inhibition Methods Of Scratch Damage On The Wafer Surface Of Magnetorheological Plane Finishing

The semiconductor wafer manufacturing field has extremely high processing requirements on the surface of the workpiece,especially for the new generation of compound semiconductor materials such as Si C,Ga As and Ga N,etc.,making it possible to achieve a high surface and high-flatness.The magnetorheological polishing technology is applied to the semiconductor wafer processing,which can obtain higher surface processing quality and processing efficiency.However,during the magnetorheological plane finishing,the ferromagnetic particles and abrasive particles in the polishing liquid agglomerate to form large-sized particles due to the interaction between the magnetic field and the workpiece.The rheological properties of the magnetorheological fluid will make the large agglomerated particles also be entrapped to cut the surface of the wafer,which will cause irregular surface scratch damage.Research on the formation mechanism of scratch damage on the wafer surface can effectively grasp the cause of the scratch formation and play an effective supporting role in constructing the analysis of the scratch damage process in MRF.It is of great significance to broaden the application range and realize the industrial application of the magnetorheological plane finishing.In this paper,the exploration of the formation mechanism and suppression methods of scratch damage on the wafer surface have been carried out:(1)Propose corresponding characterization methods according to the scratch damage characteristics of the wafer surface during the magnetorheological plane finishing.Study the formation factors of scratch damage on the wafer surface during plane finishing,clarify the relationship between agglomerated particles and wafers,and establish a nano-scratch model of agglomerated particles and wafers.The molecular dynamics method is used to simulate the scratching process of materials,to explore the formation mechanism of scratch damage on the wafer surface of during the magnetorheological plane finishing,and to study the impact on the scratches of agglomerated particles and finishing process.(2)Establish the relationship between the effect of agglomerated particles on the amount of scratch characterization,and combine it with the process parameters to realize the study of the scratch morphology of the wafer surface during the magnetorheological planar finishing.By establishing the movement trajectory model of agglomerated particles on the wafer surface,the influence of different polishing process parameters on the formation of scratches is simulated,and the correspondence between scratch characteristics and process parameters is analyzed.Combined with the material removal model in the finishing process,the scratch damage morphology of the wafer surface affected by the agglomerated particles in the presence of agglomerated particles is established.(3)The orthogonal experimental design method was used to study the significance of the influence of different polishing process parameters on the formation of scratches,and the law of influence on the characterization of scratches.Further carry out magnetorheological plane polishing experiments to study the surface quality of semiconductor wafer materials and the number of surface scratch shapes under different process parameters to obtain the optimal process parameters that can inhibit the formation of scratches.