White light interference measurement device and method based on sample space structure illumination

Abstract

The invention discloses a white light interference measurement device and method based on sample space structure illumination. A micro-display is added to an illumination system, and different space patterns can be projected to the surface of a sample; during measurement, a measurement area of the sample is divided according to an acquired sample image in combination with characteristics of the sample to form different illumination patterns; the illumination patterns are input into the micro-display, and asynchronous spatial illumination and white light interference measurement are carried outon adjacent areas, so as to avoid coherent interference signal interference caused by multiple reflections between adjacent points; and then, the plurality of groups of measured surface height distributions are combined to obtain the height distribution of the whole surface. Interference between adjacent points during white light interference measurement of samples such as a micro-groove array issuppressed by adopting a spatial pattern illumination method, and the samples can be quickly detected in a nondestructive manner.

Description

technical field [0001] The invention relates to the field of micro-nano measurement, in particular to a white light interferometric measurement device and method based on sample space structure illumination. Background technique [0002] White light interferometry can measure the roughness and microstructure profile of the surface, and the precision can reach the micro-nano level, which is a key technology in the field of micro-nano measurement. White light interference scans the sample surface vertically to obtain coherent interference signals at every point on the surface. The contrast of the coherent interference signal is maximized when the sample surface is at the same optical path as the reference mirror. Therefore, the height information of the point on the sample can be determined by analyzing the coherent interference signal of each point. Because white light interference analyzes the coherent interference signal at each point, it has high spatial resolution and h...

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Problems solved by technology

Microprobe scanning method ("B.Ju, Y.Chen, W.Zhang, et al.Note: long range and accurate measurement of deep trenchmicrostructures by a specialized scanning tunneling microscope, Rev.Scie.Instrum.2012,83:056106 ") There is no need to consider the multiple reflection interference of optical measurement methods, but limited by the length of the probe, contact force, and scanning speed, it can only measure microstructures with a depth of tens of microns, and it will scratch the surface of the sample, and the measurement time is long

The improved interferometric method is to treat the sample surface or plan the measurement process in the existing interference optical path, such as: coating the refractive index matching liquid on the sample surface to reduce the wavefront gradient ("D.Purcell, A.Suratkar, A.Davies , etal.Interferometric technique for faceted microstructure metrology using anindex matching liquid.Appl.Opt.2010,49:732"), but it can only be used for the detection of transmissive samples; establish multiple reflection models, plan from the bottom of the groove to the higher Low scanning range (“F. Fang, Z. Zeng, X. Zhang, etal. Measurement of micro-V-groove dihedral using white light interferometry, Opt. Commun. 2016, 359:297”), capable of measuring grooved surfaces , but the shape of a single facet cannot be measured because the light is reflected twice by the groove surface

The dual-system comparison method is to construct two interference microscopes with a specific angle for the groove at a specific angle, and the two interference microscopes measure the two surfaces of the micro-groove at an angle close to the normal direction at the same time (“T. Zhang, F. Gao ,H.Martin,et al.Amethod for inspecting near-right-angle V-groovesurfaces based on dual-probe wavelength scanning interferometry.Int.J.Adv.Manuf.Technol.2019,104:1"), thereby avoiding mutual interference , but the applicability of this method is not strong, it is only suitable for samples on the surface of micro grooves, and it cannot be applied to samples with multi-characteristic surfaces such as triangular pyramids

[0004] At present, the industry has not effectively solved the key parameters of microstructure array samples with high precision and small angles for non-destructive testing

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