Method and apparatus for performing film thickness measurements using white light scanning interferometry

A technology of interferometry and interferometer, which is applied in the direction of measuring devices, optical devices, instruments, etc., and can solve problems such as slow measurement speed applications

Active Publication Date: 2012-08-01
MITUTOYO CORP
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

[0014] However, in both cases, initial experiments with reflectance standards such as silicon show that these methods are limited due to their slow measurement speed and in terms of their possible applications

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  • Method and apparatus for performing film thickness measurements using white light scanning interferometry
  • Method and apparatus for performing film thickness measurements using white light scanning interferometry
  • Method and apparatus for performing film thickness measurements using white light scanning interferometry

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Embodiment Construction

[0054] Figure 2A A cross-sectional view is shown of a non-permeable substrate 1 on which a semi-transparent membrane 2 is provided. The invention aims at measuring the thickness of the film 2 initially independently of the height profile of the substrate 1 , but in a special embodiment also together with the height profile.

[0055] also, Figure 2B show with Figure 2A Similar view where the second semi-permeable layer 3 has been applied on the first semi-permeable layer 2 . The refractive index of the second layer 3 is different from the refractive index of the first permeable layer 2 .

[0056] figure 1 The entire Mirau-type interferometer denoted by 4 is drawn. This interferometer 4 comprises a light source 5 suitable for generating white light, a first lens 6 , a first mirror 7 and a second lens 8 , these units being suitable for generating a parallel light beam 9 . The parallel light beam 9 can also be generated by other components. The parallel beam 9 is reflect...

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Abstract

The invention relates to a method and an apparatus for measuring the thickness of a transparent film by broad band interferometry, comprising the steps of preparing a correlogram of the film by an interferometer, applying a Fourier transformation to said correlogram to obtain a Fourier phase function, removing a linear component thereof, applying a second integral transformation to the remaining non-linear component to obtain an integral amplitude function of said non-linear component, identifying the peak location of said integral amplitude function and determining the thickness of the film as the double value of the abscissa at said peak location considering a refractive index of a film which is dependent on wavelength. The last two steps may be replaced by identifying the peak locations of said integral amplitude function and determining the thickness of the films as the double values of the abscissas at the peak locations.

Description

[0001] This application is based on and claims the benefit of priority from European Patent Application No. 11152186.0 filed on January 26, 2011, the disclosure of which is hereby incorporated by reference in its entirety. technical field [0002] The present invention relates to high speed topographic surface and tomographic film thickness profiling using white light scanning interferometry. Background technique [0003] It is well known in the fields of science and industry that ellipsometry and spectroscopic reflectometry can be used for highly accurate film thickness measurements. Even though ellipsometry and reflectometry have been developed and improved with some techniques such as variable angle, polarization and tunable spectral bandwidth, they are usually based on single point measurement, which limits measurement speed and lateral resolution. [0004] White light scanning interferometry (WLI) has been developed to measure the topographic surface height profile of a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/06
CPCG01B11/0675
Inventor K-N.周
Owner MITUTOYO CORP
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