Patent ID: 8528407
Filing Date: 2013-09-10
Classification: G01N,H01L

Abstract:
1. A method for testing for a crack in a wafer, comprising the steps of: coupling a broad-band actuator to the wafer; connecting a plurality of sweeping frequencies to the broad-band actuator for vibrating the wafer with sweeping frequencies within a plurality of independent frequency bands; coupling at least one acoustic sensor to the wafer for simultaneously measuring a measured peak frequency, a measured amplitude and a measured bandwidth of a resonant frequency curve of the vibrating wafer; comparing the measured peak frequency, the measured amplitude and the measured bandwidth of the resonant frequency curve of the vibrating wafer with a reference peak frequency, a reference amplitude and a reference bandwidth of a reference resonant frequency curve to determine a crack in the wafer; and rejecting the wafer in the event the wafer produces a change in any two of the measured peak frequency, the measured amplitude and the measured bandwidth of the resonant frequency curve relative to the reference frequency, the reference amplitude and the reference bandwidth of the reference resonant frequency curve.