| 摘要 |
PURPOSE:To measure a period at constant high accuracy all the time and to measure a film thickness by bringing the node part of an interference wave to the central part of a CCD array (linear sensor), obtaining a fundamental period, and computing the length of a gap based on the fundamental period. CONSTITUTION:A film thickness (g) of a mask 1 is inputted into a data processing computer 18. Then the corresponding amount of correction is computed. A command is outputted into a control 17. A stage 12 is moved so that the node part of an interference wave comes to the central part of the light receiving part of a CCD array. Then, monochromatic light 3 is projected and received with the CCD array 9. The optoelectronic transduced output of the array is inputted into the computer 18 through an I/O bus 19. The collected data are processed, and the signal levels are normalized. An envelop is obtained. A convex point of inflection is obtained on the envelope. Whether the node part is located at the center of the CCD array 9 is judged based on the X coordinate of the point of inflection. The stage 12 is moved, and fine adjustment is performed. |
