Effect of crystallographic orientation and employment of different cutting tools on micro-end-milling of monocrystalline silicon

This article presents the research on the effect of crystallographic orientation and different cutting tool effect during micro-milling of (001) silicon wafer. Excessive generation of undesirable surface and subsurface damages often occurs when machined at thick depth of cut of several hundreds of microns. Up-milling operations along <100> and <110> directions were performed on a (001) wafer, and the results show that machining surfaces along <100> were of better quality than those of <110> and are in agreement with previous studies. In addition, comparative studies of diamond-coated, chemical vapour–deposited and single crystal diamond end-mills were performed along [ 0 1 ¯ 0 ] at 150 µm deep. Results have shown that diamond-coated tool generates the least edge chipping. This might be due to the large negative rake angle creating highly compressive hydrostatic pressure in the cutting zone and therefore suppressing the crack propagation. Furthermore, no visible defects were detected on the bottom-machined surface when machined by chemical vapour–deposited and single crystal diamond end-mills. Surface edge chipping however remains a challenge, even though micro-milling were performed along <100> with single crystal diamond end-mill. Apart from milling along <100>, protection to the top silicon surface is required to achieve fracture-free quality micro-milled silicon.