MATERIAL REMOVAL MECHANISM OF ABRASION-ASSISTED WEDM FOR SINGLE-CRYSTAL SILICON

抄録

Single-crystal silicon is widely used as a substrate material for integrated circuits. Typically, the wafer is cut by a wire saw with fixed diamond abrasive owning to the wire saw’s narrow kerf and low cutting force. However, the wafer has a large number of scratches by contact cutting with the wire saw, and the material removal rate (MRR) of the wire saw still needs to be improved. This paper proposes the abrasion-assisted wire electrical discharge machining (A-WEDM) process for single-crystal silicon and investigates the micro-cutting mechanism of A-WEDM by collecting and analyzing the discharge waveform during processing, observing the workpiece surface topography after processing, and comparing the diamond protrusion height and the discharge gap width. In addition, the paper also compares the difference in process performance between the wire saw machining and A-WEDM. The experimental results show that the maximum discharge gap is 57 μm, i.e., the distance between the workpiece and wire core where discharge first occurs in the initial stage of machining. When the machining is in a stable stage, within each voltage pulse material is removed under the coupling effect of discharge and diamond abrasive grinding. In each pulse interval, the electrical discharge effect stops, but the diamond abrasive grinding action still exists, thereby removing part of the recast layer and craters generated by the electrical discharge. Compared with the wire saw machining, A-WEDM has fewer scratches and higher MRR, however, the surface roughness is higher than when using wire saw machining alone.