Ultraviolet-assisted polishing of 2 inch SiC substrate

Silicon carbide (SiC) is a good candidate material for next-generation semiconductors for use in power devices. However, SiC substrates are very difficult to machine because of their mechanical hardness and marked chemical inertness. We developed a specular surface processing technology for super-high-hardness materials, such as a diamond and SiC. The new processing method uses a photochemical reaction for mechanical removal induced by ultraviolet ray irradiation. Here, we report a series of processes involved in final processing by UV-assisted polishing from pre-processing diamond lapping, to the SiC substrate with a 2-inch As-slice face. Pre-processing was performed with two steps of diamond lapping, which made a field with flatness of about 1μ m and a smooth surface of Ra 0.5 nm within 1 h from an As-slice face. By UV-assisted polishing, we were able to make a smooth surface of Ra 0.19 ? 0.28 nm and Rz 2.12 - 3.00 nm on the whole substrate, with a removal rate of 256 nm/h.