| 摘要 |
PURPOSE: To uniquely determine a groove shape on an object to be measured by utilizing only diffraction light rays from the object to be measured by injecting a plurality of linear polarized lights with differently polarized states to the object to be measured. CONSTITUTION: Incidence light IL, linearly polarized light which is emitted out of a light source 1 and whose polarization direction is determined to be parallel polarized light by a 1/2λplate 2 and a motor 6, is radiated toward a substrate 3, which is an object to be measured. The intensities of zero-order diffraction light DL0 , a primary diffraction light DL1 , and a secondary diffraction light DL2 are measured by scanning a detector 4 and based on the obtained data, a CPU 5 calculates the intensity ratio of the diffraction light rays DL1 and DL0 of parallel polarized incidence light, the intensity ratio of the diffraction light DL2 and DL1 , and the width the depth of a groove. Then, the polarization state is changed to a vertical polarization incidence by rotating the 1/2λplate 2, for example, 45 deg. and the intensity ratio of the diffraction light DL1 and DL0 of the vertically polarized incidence light and the intensity ratio of the diffraction light DL2 and DL1 and the width and the depth of the groove are calculated by scanning the detector 4 inversely to the scanning at the time of the incidence of parallel polarized light. The CPU 5 determines the width and the depth of the groove of an object to be measured by comparing these data.
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