Ultrafine ductile-mode dicing technology for SiC substrate with metal film using PCD blade

For cutting a SiC substrate coated with a metal film stably, a novel ductile-mode dicing process was developed using a blade made of a single body of poly-crystalline diamond (PCD) with only 50 mu m in thickness. It is difficult for a conventional diamond blade with metal binder to cut the SiC substrate in a straight line accurately due to insufficient buckling strength. In addition, self-sharpening effect of the cutting edge is suppressed by adhesion of metal film to blade surface. In this study, a rake face and a flank face of the cutting edge were formed by irradiating pulsed laser light tangentially to the cutting edge. Under the high speed rotation condition of 30,000 rpm (500 s(-1)), the developed PCD blade acts on the workpiece with the continuous cutting edge in a stable posture due to the inertial force of the rotation, and the depth of cut per a cutting edge is about 5 nm. Under these conditions, the ultrafine cutting tip of the metal film also becomes on the order of nanometers. 4H-SiC substrate 350 mu m in thickness with Au / Ni / Ti film was cut using the developed PCD blade. Under the half cut condition, there was no chipping or crack on the surface, and the bottom of the groove was finished in a mirror state. Under the full cut condition with a width of 50 mu m, the SiC substrate and the metal film were cut at once, and any crack did not occur at the interface between SiC and the metal film. As the result, it was demonstrated that ductile mode machining was realized and the metal film did not adhere to the cutting edge.