Patent ID: 6895342

Claim:
A non-destructive method for characterizing a test sample of a sputter target material defining a surface, said method using one or more calibration values and comprising the steps of: a) sequentially irradiating the test sample with sonic energy at a plurality of positions on the surface; b) detecting echoes induced by the sonic energy; c) discriminating texture-related backscattering noise from the echoes to obtain modified amplitude signals; d) comparing the modified amplitude signals with the one or more calibration values to detect i) flaw data points at certain positions of the plurality of positions where comparison of the modified amplitude signals with the one or more calibration values indicates at least one flaw, and ii) no-flaw data points at other positions of the plurality of positions where comparison of the modified amplitude signals with the at least one calibration value indicates no flaw; e) binding groups of the flaw data points corresponding to single large flaws so as to generate an adjusted set of flaw data points in which each group of the groups of flaw data points is replaced with a single, most significant data point; f) counting members of the adjusted set of flaw data points to determine at least one flaw count C F ; g) determining a total number of data points C DP ; and h) calculating a cleanliness factor F c =(C F /C DP )×10 6 .