METHOD AND APPARATUS FOR NONDESTRUCTIVELY MEASURING SUBSURFACE DEFECTS IN MATERIALS

摘要

METHOD AND APPARATUS FOR NONDESTRUCTIVELY MEASURING SUBSURFACE DEFECTS IN MATERIALS A method and apparatus are disclosed for nondestructively measuring the density and orientation of crystalline and other micro defects directly below the surface of a properly prepared material such as a semiconductor wafer. The material surface is illuminated with a probe beam of electromagnetic radiation which is limited to a nondestructive power level and with a wavelength, or wavelengths, 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 the detector is required to detect that portion of the probe beam scattered from the subsurface region without interference from the surface scatter and to identify the orientation of the defects. Maps of scatter intensity versus position are made according to the density of the defects in the subsurface.