| 摘要 |
PURPOSE:To enable measurement of the precision of superposition by a measuring machine by using patterns for visual inspection, by a method wherein only first and second discrete pattern groups are scanned by a light beam, edge positions of the patterns are determined by sensing reflected lights therefrom and the precision of superposition of layers of the first and second patterns is determined on the basis of the edge positions. CONSTITUTION:A laser light flux of a light source 1 is scanned by a reciprocating mirror 14, shifted in the direction perpendicular to the scanning direction by a parallel flat plate 15, transmitted through a beam splitter 3, reflected by a total reflection mirror 4 and cast on an objective lens 5. The light converged by the lens 5 is imaged on a sample 7 and made to scan. A reflected light from the sample 7 enters a reflected light detector 8. A signal obtained through photoelectric conversion by the detector 8 is converted into a digital signal and then taken in a memory 12 synchronously with an interference signal of an interferometer 10. Data in the memory 12 are processed by CPU 13 so as to determine edge positions, the precision of superposition is calculated and a measured value is displayed in CRT and the like. |
