| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for the measurement of a surface shape, wherein the surface of a wafer or the step shape of an optical element or the like and the surface shape such as the face roughness, the face shape or the like of a surface can be measured with high accuracy in a noncontact manner, without being subjected to a restriction, regarding the step of an object to be measured, or without being influenced by a phase shift, even if the depth of focus is small in a state that a beam diameter is narrowed down. SOLUTION: Two beams as a condensed laser beam and an uncondensed laser beam, which are composed of two-wavelength laser beams are made incident on the wafer 19. The condensed beam controls a wafer (z) stage 30, on which the wafer 19 is placed in such a way that it is focused on the wafer 19. Two beams of reflected light from the wafer 19 and beams of reference light L1, L2 which are composed of the dual-wavelength laser beams are made to interfere in heterodyne. The surface shape on the surface of the wafer 19 is measured directly in a noncontact manner, on the basis of a phase difference signal. |
