MEASURING INSTRUMENT OF INTERVAL BETWEEN IDENTIFICATION MARKS

• Main Authors: AYADA NAOKI, KUROKI YOUICHI, HAMAZAKI FUMIYOSHI, MATSUMURA TAKASHI
• Format: Patent
• Language: English
• Published: 12.12.1985
• Subjects: MEASURING; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS; MEASURING LENGTH, THICKNESS OR SIMILAR LINEARDIMENSIONS; PHYSICS; TESTING

PURPOSE:To enable more precise and stable measurement of the interval of identification marks by the means of detecting the signal position transmitted from the 1st identification mark and of setting uniformly the necessary timing for detecting the 2nd signal on that basis. CONSTITUTION:The value for detecting the signal transmitted from the 1st mask 1 is set up in advance and set to counters 20, 21. The peak detection of only the signal transmitted from a mark AM of the mask 1 is performed thereby and the peak position is stored in RAM24 and the peak value in RAM of the inside of a peak value detecting circuit 27. The value of a slice level setting circuit 26 is adequately set by the detected peak level and only the signal of AM is measured again. On the basis of the re-setting thereof CPU detects the AM position from a memory 24. The winding times of counters 20, 21 are then re-set and counters 28, 29 are preset in order that the mask signal comes at the time of the timing thereof. No influence is thus exerted by the noize, etc. of the signal to be detected by light-scanning both a wafer 2 and the mask 1 simultaneously after the setting-up of each timing.