Abstract: A hard material-coated wafer that having a distortable substrate and a hard material film deposited thereon by a CVD method is provided. The substrate is substantially flat while in a free-standing state. However, deposition of the hard material film having a Vickers hardness of more than Hv3000 on the substrate causes the substrate to distort into a generally convex-shape. Specifically, the wafer is distorted to the film side with a distortion height H of -150 .mu.m to -2 .mu.m. The resulting wafer can have a total thickness that ranges from 0.1 mm to 2.1 mm; and a diameter that is bigger than 25 mm. Moreover, more than 50% of the film can be polished to a roughness less than Rmax 50 nm and Ra 20 nm.