Surface shape measuring apparatus

Surface states have traditionally been measured with apparatuses such as an atomic force microscope (AFM), and these measurements have been high in resolution but low in speed. In conventional apparatuses for inspecting the foreign matter sticking to a wafer surface, and for inspecting defects present on the wafer surface, the inspection has had a tendency to be restricted in a region of the highest noise level arising from the roughness of the surface, the surface state, and/or crystal orientations, and thereby to reduce detection sensitivity in a region of lower noise levels. In these conventional techniques, signal processing of the light scattered from the object to be inspected has been based only upon the intensity of the light. This invention acquires three-dimensional data by, during such signal processing, adding detection intervals and the frequency of detection, as well as the intensity of light. The invention measures surface roughness of a target object (wafer) by creating region-specific three-dimensional maps from the three-dimensional data, then estimating the surface state of the wafer from analytical results, processing this estimated surface state as physical quantities, and analyzing the data.