Pulse electromagnetic field-assisted chemical mechanical polishing utilizing magnetic composite abrasives slurry and its polishing performance

Abstract

A polishing method assisted by an auxiliary pulse electromagnetic field was proposed, where the magnetic polymer microspheres/SiO composite abrasives were anchored on a smooth glass tool plate by the magnetic force, and the dependence between diameter of composite abrasives and morphology of tool plate was reduced. In polishing processes, the abrasives entered into the polishing area easily by mean of pulse electromagnetic force, and a high material removal rate was obtained. An electromagnet with contrapuntal structure was designed, and simulation calculations show that uniform distributions of magnetic flux density and electromagnetic force are achieved. Force analyses indicate that the electromagnetic force can help the magnetic polymer microspheres enter the polishing area from near-polishing area, and material is polished by magnetic composite abrasives in two-body abrasion wear mechanism. Owing to the pulse electromagnetic force, magnetic composite abrasives is deposited and entered into polishing area easily without the occurrence of magnetic abrasives aggregation. Experiments of polishing silica wafer, using a glass tool plate of Ra 1.1 μm surface roughness and pulse electromagnetic field with a certain frequency and duty cycle, have shown the superior characteristics. The material removal rate is increased from 137 nm/min to 288 nm/min with the assistance of the electromagnetic field of 5 Hz frequency and 50% duty cycle, and the surface roughness of wafer is decreased from Ra 405 nm to Ra 0.641 nm.