"Measurement of Silicon Strength as Affected by Wafer Back Processing"

The distribution of strength of silicon chips has been measured by bending a chip between a soft ball and pad. The chip strength is controlled by flaws introduced by processing and the critical flaws can be located and analyzed after the chip breaks. The flaw sizes can be predicted reasonably well from the fracture toughness of silicon. Wafer back etching strengthens the chip, but the response depends on whether the wafer was lapped or ground.