| 摘要 |
PURPOSE:To enable rational and economical surface inspection, by dividing the surface of a substrate into a plurality of regions with due regard to the density of patterns and comparing the foreign matter data obtained by laser scanning with the judging reference value set to each region. CONSTITUTION:As a substrate 1, for example, there is a mask blank and the surface of the mask blank is scanned by laser beam through a laser oscillator 3 for detecting the foreign matter adhered to the surface thereof, an optical system 4 and a vibration mirror 5 and the scattered light reflected from said surface is condensed by a light condenser 6 to be inputted to a foreign matter detection circuit 7 while a tolerant limit memory circuit is provided at every region of the master blank storing the tolerant limits of the quantity and the size of the foreign matter adhered to the surface of the master blank. The output from a detection circuit 7 is compared with the output from the memory circuit 11 at every region by a comparing circuit 12 and quality judgment is performed by a discrimination circuit 13. |
