Device for measuring surface roughness of material surface of planar measuring object i.e. mirror, in e.g. semiconductor industry, has determining unit for determining surface roughness based on interference fringe contrasts

摘要

The device (500) has a light source (200) i.e. multi-wavelength laser, for emitting coherent light with multiple wavelengths. An interferometer (100) is attached at the light source for receiving two interferograms (203) of a material surface (109) to be examined with two synthetic wavelengths provided by two wavelength distances. A contrast detecting unit detects two interference fringe contrasts of the interferograms. A determining unit determines surface roughness based on the interference fringe contrasts. A wavelength setting unit (204) sets the wavelengths of the coherent light. The interferometer is selected from a group comprising a Michelson interferometer, a Mach-Zehnder interferometer and a speckle interferometer. An independent claim is also included for a method for measuring surface roughness of a material surface to be examined.