Method and apparatus for nondestructively measuring micro defects in materials

摘要

A method and apparatus are disclosed for nondes­tructively measuring the density and orientation of crystalline and other micro defects on and directly below the surface of a properly prepared material such as a semiconductor wafer (10). The material surface (15) is illuminated with a probe beam (16) of electromagnetic radiation which is limited to a nondestructive power level or levels. Polarization and wavelength or wave­lengths of the electromagnetic radiation are selected according to certain characteristics of the material so that penetration depth is controlled. Specific orientation of the material with respect to the probe beam and a detector is required to detect that portion of the probe beam scattered from the defects of interest, surface or subsurface, without interference from other scatter sources and to identify the orientation of the defects. Maps of scatter intensity versus position are made according to the density of the defects encountered.