Material removal and surface generation mechanisms in diamond wire sawing of silicon crystal

Silicon crystal is usually first cut into wafers in the applications of electronic devices and photovoltaic solar cells. At present, fixed abrasive wire sawing technology has been widely used in slicing. The mechanism of material removal and surface generation during wire sawing is the key basic problem to study the surface quality of sliced wafers, which is important to realize high-precision slicing. This paper presents theoretical analysis on the relationship between the average cutting depth of abrasives distributing in different positions along the wire circumferential surface and the process parameters. The wire sawing experiments of single crystal silicon were carried out, then the morphologies of sawn surface and swarf were observed, the surface roughness was measured and analyzed, the material removal and surface generation mechanism of single crystal silicon cut by electroplated diamond sawing wire were addressed. Research results show that there is an approximate nonlinear increasing relationship between the average cutting depth of the abrasives and the ratio of the workpiece feed speed to the wire speed, and the abrasives cutting depth and surface roughness of sliced wafers increases with the increasing of ratio value. It is difficult to obtain the sliced surface in a fully ductile mode of material removal in the actual wire sawing process because there are always a small amount of abrasives with high protrusion on the wire surface whose cutting depths are greater than the critical ductile regime cutting depth, but adopting a low ratio can make the generation of the sliced wafer surface in near-ductile or local-ductile material removal mode which can produce high quality wafer surface. This research is expected to be useful in optimizing the combination of process parameters in fixed abrasive diamond wire saw precision slicing of silicon wafers.