Abstract
Advanced lapping tools have been required to raise the yield rate of silicon wafer. Silicon is brittle material because the fracture toughness of monocrystalline silicon is 0.8 MPam^<1/2>. Therefore, to lap silicon wafer in the ductile mode, it is important to ensure the microscopic incision below 0.1 μm. The present authors propose Partial Functionally Graded Ceramics (PFGC) as an advanced lapping tool. PFGC can make microscopic surface asperity with polishing substances because there is stiffness distribution formed by partial electron beam irradiation in the surface of PFGC. To determine the most suitable distribution of surface-hardened layer, FEM analyses on microscopic surface asperity between PFGC and silicon were conducted with two parameters; the width of electron beam irradiation and the distance of surface-hardened layer. Microscopic surface asperity formed by PFGC was evaluated to be much smaller than the above microscopic incision. So it was found that the most suitable distribution depends on the angle and the number of microscopic surface asperity. The most suitable distribution of surface-hardened layer was evaluated that the width of electron beam irradiation is nearly 0 μm and the distance of electron beam irradiation is 20 μm.
