Theoretical And Experimental Studies On The Effect Of The Batwing Effect On The Three-dimensional Resolution Of White Light Interference Microscopy

Micro-nano structure detection methods continue to develop,and now mainly use the white light interference microscopy detection method,but due to the diffraction at the edge of the step,the batwing artifacts will appear at the edge of the step,which seriously affects the acquisition of height information.This phenomenon is particularly evident when the lateral dimension of the step reaches the resolution limit.Therefore,taking the batwing effect as an example,exploring the relationship between horizontal resolution and vertical resolution in white light interference microscopy imaging,to find an effective method to suppress or reduce the batwing effect,has important scientific significance and application value for the accurate extraction of three-dimensional microscopic information.This article explores the theoretical explanation of the batwing effect,the concept of detecting blind spots is analyzed in depth,and a series of standard step structures and periodic gratings are selected to study the relationship between batwing artifacts and step height,period and numerical aperture of the interference microscope objective.Through the experimental results,it can be found that the PSI(Phase shiftting interferometry)mode can accurately obtain the three-dimensional morphology of the low step height(the step height is less than a quarter of the wavelength),while the VSI(Vertical scanning interferometry)mode is suitable for the three-dimensional morphology of the high step height.PSI method has no batwing artifacts,and VSI method will bring batwing artifacts.With the increase of the numerical aperture of the objective lens,the batwing effect increases but is still in the order of nanometers.If batwing artifacts are removed,accurate height information can be obtained.This paper presents a high-precision and fast measurement algorithm-V-P fusion edge removal algorithm.Within a certain scan length,time-series vertical scanning is performed according to the phase step amount of ?/2,and an interferogram is stored corresponding to each step amount.The calculation process of the interferogram is integrated into the process of timesequential vertical scanning and storage of the interferogram to realize fast measurement.At the same time that the vertical scanning and recording of the interferogram are completed,the precise phase of the phase shift scanning of each pixel point in the air domain and the contrast of multiple interferograms are solved.The contrast of multiple interferograms is processed to obtain the vertical scanning coarse phase.Then,the fine phase and the coarse phase are fused to obtain the three-dimensional topography measurement result.Finally,the two-dimensional discrete difference algorithm is used to judge and eliminate the batwing error generated at the edge of the step shape in the sample to be tested,so that the shape curve can be restored more accurately,and the accuracy of the vertical and horizontal resolution is ensured.