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US 7,403,270 B2Granted
Method for whole field thin film stress evaluation
AssigneeInstrument Technology Research Center, National Applied Laboratories
InventorsChi Hung Huang, Hsien-I You, Mao-Yuan Shih, Chien-Jen Chen
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Abstract
A novel method for whole field thin film stress evaluation is provided. Through the provided method, the whole filed thin film stress distribution for an optical thin film would be developed with a commercial interferometer, so that a whole field evaluation for the crack or peel-off of thin film is hence achievable.
Claims13
A method for evaluating a whole field stress in a thin film, comprising:
- (a) preparing a substrate;
- (b) measuring a wavefront for said substrate with a laser having a wavelength of λ so as to obtain a first wavefront phase;
- (c) depositing an optical thin film on said substrate as a specimen;
- (d) measuring a wavefront for said specimen so as to obtain a second wavefront phase;
- (e) determining a phase difference between said first wavefront phase and said second wavefront phase by means of an image subtraction;
- (f) fitting said phase difference with Zernike polynomials so as to obtain a fitting result for a respective surface topography of said substrate and said specimen;
- (g) retaining a coefficient of a specific term of said Zernike polynomials according to said fitting result, wherein said specific term is corresponding to a strain for said whole field stress;
- and
- (h) obtaining said whole field stress according to said coefficient of said specific term.
6 more elements
A method for evaluating a whole field stress in a thin film, comprising:
- (a) preparing a substrate;
- (b) measuring a wavefront for said substrate with a laser having a wavelength of λ so as to obtain a first wavefront phase;
- (c) depositing an optical thin film on said substrate as a specimen;
- (d) measuring a wavefront for said specimen so as to obtain a second wavefront phase;
- (e) fitting said first wavefront phase and said second wavefront phase with a Zernike polynomial respectively;
- (f) determining said phase difference by means of numerical subtraction of the coefficients so as to obtain a result for a respective surface topography change of said substrate and said specimen;
- (g) retaining a coefficient of a specific term of said Zernike polynomials according to said fitting result, wherein said specific term is corresponding to a strain for said whole field stress;
- and
- (h) obtaining said whole field stress according to said coefficient of said specific term.
6 more elements
Dependencies are inferred from the claim text.