Study On The Application Of Linnik Microscopic White Light Spectral Interferometry

With the development of science and technology and the continuous advancement of micro-nano processing technology,the high-precision measurement of for micronano structure has become a hotspot of research.In order for micro-nano device to realize its function,high-precision and fast measurement of various characteristics of the device is very important.At present,there are many kinds of measurement methods with mechanical scanning processes.However,the measurement time is long,and the results are easily affected by environmental vibrations,consequently the measurement speed and accuracy cannot be considered simultaneously.For the above-mentioned problems,in order to achieve high-precision rapid measurement,this thesis studies the application of Linnik microscopic white light spectral interferometry.A method for rapid measurement of large step heights is proposed to ensure measurement accuracy while significantly reducing measurement time by means of non-scanning measurement.A spectral synchronous phase shift interferometry method is proposed.The phase shift is introduced based on the polarization principle.The measurement speed is improved by reducing the amount of data required to extract the phase.Therefore,the main work of this thesis is as follows:1.A method for rapid measurement of large step heights is proposed.The effects of the optical path difference of the measurement position and the step measurement position on the measurement results are studied.The rapid measurement is realized by the non-scanning approach.The measurement accuracy reaches nanometer,the data processing time is within 1 second,and the repeatability is good.Compared with the one-dimensional linear scanning step measurement method and white light vertical scanning interference method,the accuracy is the same,but the measurement time is significantly shortened.2.The Linnik microscopic white light spectral interference system is designed and built.The system is compatible with various measurement methods such as white light vertical scanning interference,white light spectral interference and synchronous phase shift interference,and the flexibility and diversity of the system are improved.3.A spectral synchronous phase shift interferometry method based on the principle of polarization is studied,the two-step phase shift method is used to extract the phase.Through simulation experiments,the effects of light intensity,spectral shape and phase difference of the two frames of phase shift signals on the measurement results are studied.It is determined that the two frames of phase shift signals are normalized to effectively reduce the impact on the measurement results.At the same time,the differences in measurement accuracy and calculation time of two-step phase shift method,five-step phase shift method and Fourier transform method,are compared by simulation experiments.Finally,the absolute distance verification measurement is carried out,which proves that the system has nanometer precision,which proves the feasibility of the measurement system and measurement method.The results of the simulation experiments are in good agreement with the experimental results.