A method and device for interferometric measurement of surface topography

Abstract

The invention relates to the field of surface appearance measurement and discloses a method and device for surface appearance interference measurement based on combination of multi-wavelength alternation and phase shift scanning. The method comprises the following steps that 1: a light source is started; 2: images are collected; 3: the light source is switched; 4: whether the light source is switched successfully or not is judged, and if the answer is negative, the step 2 is conducted; if the answer is positive, the position of a reference mirror is changed and interference signals of laser with different wavelengths in different positions of the reference mirror are collected; 5: whether collection is completed or not is judged, and if the collection is not completed, the step 1 is conducted; if the collection is completed, the data signals are processed and sample appearance parameters are calculated and displayed. The device for the surface appearance interference measurement comprises a light source unit, an interference microscopic measurement unit, an image collecting unit, a multi-wavelength switch unit, a piezoelectric ceramic PZY driving unit and an image processing and control unit. According to the method and device for the surface appearance interference measurement, the advantages of wavelength scanning and the phase shift scanning are fully used, so that high-accuracy absolute measurement of surface appearance is achieved.

Description

technical field [0001] The invention relates to the field of surface topography measurement, and discloses a method and device for surface topography interferometry based on the combination of multi-wavelength rotation and phase shift scanning. Background technique [0002] Surface topography measurement plays an extremely important role in ultra-precision testing, especially in the semiconductor industry and optical device processing. At present, ultra-precision surface measurement methods are mainly divided into non-optical measurement and optical measurement. The non-optical measurement methods mainly include: stylus profilometry, scanning electron microscopy (SEM), scanning probe microscopy (SPM), etc.; Optical interferometry methods mainly include: white light phase-shifting interference, multi-wavelength interference and wavelength scanning, etc. [0003] Among non-optical measurement methods, stylus profilometry is a contact measurement method, which is likely to scr...

AI Technical Summary

Problems solved by technology

The dual-wavelength or multi-wavelength measurement method is to use the difference between the dual-wavelength and multi-wavelength measurement results to obtain the interference order, so as to obtain the true depth of the measured point, without wavelength switching, but the interference pattern is of low precision. The light intensity of the colored light is too weak, and the signal-to-noise ratio of the interference pattern is low

The optical interferometry technology based on wavelength scanning changes the wavelength by continuously changing the frequency of the RF driver, resulting in changing the relative phase difference while the absolute optical path difference remains unchanged. It does not require a corresponding driving device, but it cannot judge the surface topography. In the height direction, due to the impact of wavelength scanning range and resolution, the recognition range is difficult to improve

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