Patent ID: 8740670

Claim:
A method of machining a sapphire substrate comprising: grinding a first surface of a sapphire substrate using a first fixed abrasive, and grinding a second surface of the sapphire substrate, opposite the first surface, wherein the first fixed abrasive is self dressing; grinding said first surface of the sapphire substrate using a second fixed abrasive, wherein the second fixed abrasive has a smaller average grain size than the first fixed abrasive, the second fixed abrasive being self-dressing; and wherein after grinding the sapphire substrate using the second fixed abrasive, the sapphire substrate comprises a normalized total thickness variation (nTTV) is not greater than about 0.037 μm/cm 2 , a normalized bow (nBow) not greater than 0.100 μm/cm 2 , and a normalized flatness (nFlatness) of not greater than 0.100 μm/cm 2 .