Surface profile measuring method and apparatus thereof

Abstract

A surface profile measuring method is disclosed, a wide band optical source is split via the beam splitter and then irradiates separately on the surface of the object to be detected and a reference plane, the reflected lights come from the two surfaces interfere with each other, the distance between the object surface and the beam splitter is changed by a fixed step to generate a interference pattern whose height value is corresponding with the light intensity. Then the interference pattern is scanned to find out the first interference fringe which is in respect with the maximum light intensity. And then the second interference fringe which has the most perfect symmetrical characteristic is be found out from the first interference fringe and its nearby fringes based on the symmetry principle of the interference pattern. Based on the second interference fringe, the position with zero optical path difference where is in corresponding with the wave crest of the second interference fringe can be calculated by the phase compensation method, that is the height value of the object surface which is to be detected.

Description

technical field [0001] The present invention relates to a surface profile measuring method (Surface Profile Measuring Method) and its measuring device, in particular to a surface profile measuring method and its measuring device in a non-contact manner by using a broadband light source. Background technique [0002] The shape measurement device that uses the characteristics of white light interferometry to measure the surface shape of objects in a non-contact manner is widely used in products that require high precision, such as: semiconductor wafers, glass for liquid crystal displays panel etc. [0003] Please refer to FIG. 1 , which is a schematic diagram of a typical non-contact shape measurement device. As shown in the figure, the profile measurement device has a broadband light source 10, a collimation lens (collimation lens) 20, a 45-degree beam splitter (Splitter) 30, an imaging eyepiece 40, an image sensing device 50, an An interference microscope objective lens se...

AI Technical Summary

Problems solved by technology

[0012] Basically, this method has the following disadvantages: 1. The calculation of fringe comparison is huge, and it takes a lot of time; 2. This method is not good against noise. Once there is obvious noise near the zero-order interference fringe, the If the interference fringe with the largest light intensity contrast deviates from the zero-order interference fringe, then the zero optical path difference position obtained by subsequent calculations will be different from the actual zero optical path difference position by an integer multiple of the phase difference of 360 degrees

It is worth noting that although this method can accurately calculate the surface topography of the object to be measured, the amount of data generated by the frequency domain conversion and the least square approximation method is very large, and it takes a considerable amount of time

[0014] As mentioned above, in the process of estimating zero optical path difference, the known methods either cannot effectively eliminate the influence of noise, which is prone to errors, or generate a huge amount of data in the calculation process, which consumes a lot of time, and cannot At the same time, the accuracy of measurement and the speed of calculation are taken into account

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