JPS6423144A - Method for detecting flaw in thin film layer of crystal substrate - Google Patents

Abstract

PURPOSE:To inspect a crystal flow in a thin film layer without any destruction by projecting a laser beam on the thin film layer at a specific angle of incidence and generating a pseudo surface wave in the thin film layer. CONSTITUTION:The laser beam 100 from a laser source 34 is incident on a prism 22 through an optical system 36, but the angle theta of incidence can be adjusted finely and optionally by an angle adjusting mechanism 38 provided successively on the laser source 34. Here, the laser beam 100 is projected on the thin film layer at the angle of incidence in the vicinity of a critical angle and scattered or diffracted light from the defect is detected by a TV camera 40 above a wafer 20 according to the pseudo surface wave generated in the layer. Further, a pulse motor 32 is driven according to the line width of the signal from the image input device 42, a sample table 30 is fed successively by a specific movement quantity to scan the entire area of the thin film layer 100, and scattered light generated by the entire-area scanning is stored in a memory 48. Then, a two-dimensional image is read out optionally and the crystal flaw in the thin film layer is inspected easily and speedily without any destruction.