| 摘要 |
Optical monitoring of the lateral dimensions of a pattern disposed on a substrate in the form of a wafer or mask is accomplished by testing for the lateral dimensions of a diffraction grating test pattern disposed adjacent the pattern. A beam of monochromatic light such as from a laser is diffracted by the test pattern and detectors determine the intensity of the diffracted beams. The detectors are disposed in a plane orthogonal to the plane of the test pattern and to the direction of the grating lines. The detectors are selectively spaced from each other according to the periodicity d of the grating and the width of the grating lines a is determined from a relationship of the detected intensities of the beams. |
