Apparatus for measuring the distribution of irregularities on a mirror surface

• Main Author: TAKASU; SHINICHIRO
• Format: Patent
• Language: English
• Published: 29.09.1981
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

An optical apparatus for measuring irregularities on the mirror surface of, for example, a silicon wafer used to provide a semiconductor integrated circuit. Irradiates on the mirror surface light fluxes arranged in a special form, for example, in the lattice form. By observing the pattern of light fluxes reflected from said mirror surface, one can measure the surface irregularities. A light flux issued from a light source is divided by a photomask or diffraction grating into first light fluxes irradiated all over the mirror surface and second light fluxes surrounding the respective first light fluxes in the continuous or discontinuous annular form, thereby ensuring the simultaneous measurement of the distribution of extensive irregularities over the entire mirror surface by the first light fluxes and the distribution of local irregularities on said mirror surface by the second light fluxes.