Patent ID: 7909678

Claim:
A method of making thin silicon wafers from a silicon block with a reduced wafer fracture rate, said silicon block having lateral surfaces, said method comprising the steps of: a) providing a coarse grained cylindrical grinding tool with cylindrical walls comprising coarse grains embedded in a matrix material and a fine grained cylindrical grinding tool with cylindrical walls comprising fine grains embedded in said matrix material, wherein said matrix material is selected from the group consisting of soft metal, polymers and resins, and wherein said coarse grains or said fine grains are diamond grains, silicon carbide grains or silicon nitride grains, said coarse grains have mean diameters that are at least 80 μm, and said fine grains have mean diameters that are not greater than 40 μm; b) coarse grinding the lateral surfaces of the silicon block with said coarse grained cylindrical grinding tool; c) after the coarse grinding of step b), fine grinding the lateral surface of the silicon block with said fine grained cylindrical grinding tool; d) grinding off a layer that has a thickness of 20 μm to 400 μm from said lateral surfaces of said silicon block by the grinding of step b) and step c) in order to remove subsurface defects that cause fractures; and e) after the grinding of step b) and of step c), cutting a plurality of said silicon wafers from said silicon block; whereby edge surfaces of the silicon wafers are formed from said lateral surfaces of said silicon block and fracture of said silicon wafers by said cutting is minimized.