| With the rapid development of modern electronics,communications and optics and other industries,world demand for semiconductors,optical crystal and other materials is growing.At present,the main way to obtain high precise surface of these materials is the free abrasive polishing.The polishing solution and abrasive will fast leave the processing area under the effect of centrifugal force.Which lead to uneven distribution of the polishing solution and abrasive and low polishing efficiency.In order to overcome the shortcomings of the traditional polishing method,this paper puts forward dielectrophoresis polishing method.In this paper,the principle of dielectrophoresis polishing method is studied.Based on the basic theory of electrostatic field,to calculate the electric dipole moment of the ideal spherical abrasive,and then deduce the dielectrophoresis force expression of the ideal spherical abrasive in the non-uniform electric field.It lays the foundation for studying affecting factors of dielectrophoresis polishing.For dielectrophoresis polishing experimental study,this paper designs experimental equipment for dielectrophoresis polishing.It includes two parts,the power for generating non-uniform electric field of dielectrophorisis.and the polishing apparatus for manufacturing workpiece.The power can output frequency from 0Hz to 50 Hz,amplitude from 0V to 3000 Hz square-wave voltage.When the power connects to the electrodes of the polishing apparatus,dielectrophoresis polishing was achieved.Go through simulation of the non-uniform electric field under different electrode shapes by COMSOL,the electric field intensity square gradient was obtained.It can reflect the dielectrophoresis force of abrasive in the non-uniform electric field under different electrode shapes.After analyzing the dielectrophoresis force of abrasive in the non-uniform electric field under different electrode shapes,it is concluded that the polishing effect is the best for3 inch silicon wafer under the circle electrode of 60 mm in diameter.Through studying for voltage,frequency,processing load and polishing speed,it draws a conclusion that frequency 40 Hz,voltage 1500 V,processing load 4000 g and pad speed60r/min is the best experiment condition.By the contrast experiment of the dielectrophoresis polishing and the traditional polishing,it is concluded that,compared with the traditional polishing,the surface roughness on wafer polished by dielectrophoresis polishing decreases more quickly and the removal rate is higher.In other words,the dielectrophoresis polishing is superior to the traditional polishing. |
