Abstract

Measuring the thickness of thin films is strongly required in the display industry. In recent years, as the size of a pattern has become smaller, the substrate has become larger. Consequently, measuring the thickness of the thin film over a wide area with low spatial sampling size has become a key technique of manufacturing-yield management. Interferometry is a well-known metrology technique that offers low spatial sampling size and the ability to measure a wide area; however, there are some limitations in measuring the thickness of the thin film. This paper proposes a method to calculate the thickness of the thin film in the following two steps: first, pre-estimation of the thickness with the phase at the peak position of the interferogram at the bottom surface of the thin film, using white-light phase-shift interferometry; second, accurate correction of the measurement by fitting the interferogram with the theoretical pattern through the estimated thickness. Feasibility and accuracy of the method has been verified by comparing measured values of photoresist pattern samples, manufactured with the halftone display process, to those measured by AFM. As a result, an area of 880 × 640 pixels could be measured in 3 seconds, with a measurement error of less than 12%.

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  1. P. A. Flourney, R. W. McClure, and G. WyntjesWhite-light interferometric thickness gaugeAppl. Opt.19721119071915
  2. H. Maruyama, S. Inoue, T. Mitsuyama, M. Ohmi, and M. HarunaLow-coherence interferometer system for the simultaneous measurement of refractive index and thicknessAppl. Opt.20024113151322
  3. P. Hlubina, D. Ciprian, J. Lunacek, and M. LesnakDispersive white-light spectral interferometry with absolute phase retrieval to measure thin filmOpt. Express20061476787685
  4. S. K. Debnath, M. P. Kothiyal, J. Schmit, and P. HariharanSpectrally resolved white- light phase-shifting interference microscopy for thickness profile measurement of transparent thin-film layers on patterned substratesOpt. Express20061446624667
  5. P. Hlubina, J. Lunacek, and D. CiprianWhite-light spectral interferometric technique to measure a nonlinear phase function of a thin-film structureOpt. Commun.201028348774881
  6. Y. S. Ghim and S. W. KimSpectrally resolved white-light interferometry for 3D inspection of a thin-film layer structureAppl. Opt.200941799803
  7. S. W. Kim and G. H. KimThickness-profile measurement of transparent thin-film layers by white-light scanning interferometryAppl. Opt.19993859685973
  8. Y. M. Hwang, S. W. Yoon, J. H. Kim, S. Kim, and H. PahkThin-film thickness profile measurement using wavelet transform in wavelength-scanning interferometryOpt. Lasers Eng.200846179184
  9. D. MansfieldThe distorted helix: thin film extraction from scanning white light interferometryProc. SPIE2006618661860O
  10. D. MansfieldExtraction of film interface surfaces from scanning white light interferometryProc. SPIE20087101797978
  11. B. Maniscalco, P. M. Kaminski, and J. WallsThin film thickness measurements using scanning white light interferometryThin Solid Films20145501016
  12. D. S. Kim and S. H. KimFast thickness profile measurement using a peak detection method based on an acousto-optic tunable filterMeas. Sci. Technol.200213L1L5
  13. J. W. You, S. Kim, and D. KimHigh speed volumetric thickness profile measurement based on full-field wavelength scanning interferometerOpt. Express2008162102221031
  14. T. Jo, K. Kim, S. R. Kim, and H. J. PahkThickness and surface measurement of transparent thin-film layers using white light scanning interferometry combined with reflectometryJ. Opt. Soc. Korea201418236243
  15. H. G. Tompkins and W. A. McGahanSpectroscopic ellipsometry and reflectometry: a user’s guideJohn Wiley & Sons INNew York1999821
  16. K. G. LarkinEfficient nonlinear algorithm for envelope detection in white light interferometryJ. Opt. Soc. Am. A.199613832843
  17. P. de Groot and L. DeckThree-dimensional imaging by sub Nyquist sampling of white -light interferogramsOpt. Lett.19931814621464
  18. J. Schwider, R. Burow, K.-E. Elssner, J. Grzanna, R. Spolaczyk, and K. MerkelDigital wave-front measuring interferometry: some systematic error sourcesAppl. Opt.19832234213432
  19. K. ItohAnalysis of the phase unwrapping problemAppl. Opt.19822124702470
  20. S. R. Kim, J. H. Kim, and H. J. PahkFringe-order determination method in white-light phase-shifting interferometry for the compensation of the phase delay and the suppression of excessive phase unwrappingJ. Opt. Soc. Korea201317415422

Other (20)

P. A. Flourney, R. W. McClure, and G. WyntjesWhite-light interferometric thickness gaugeAppl. Opt.19721119071915

H. Maruyama, S. Inoue, T. Mitsuyama, M. Ohmi, and M. HarunaLow-coherence interferometer system for the simultaneous measurement of refractive index and thicknessAppl. Opt.20024113151322

P. Hlubina, D. Ciprian, J. Lunacek, and M. LesnakDispersive white-light spectral interferometry with absolute phase retrieval to measure thin filmOpt. Express20061476787685

S. K. Debnath, M. P. Kothiyal, J. Schmit, and P. HariharanSpectrally resolved white- light phase-shifting interference microscopy for thickness profile measurement of transparent thin-film layers on patterned substratesOpt. Express20061446624667

P. Hlubina, J. Lunacek, and D. CiprianWhite-light spectral interferometric technique to measure a nonlinear phase function of a thin-film structureOpt. Commun.201028348774881

Y. S. Ghim and S. W. KimSpectrally resolved white-light interferometry for 3D inspection of a thin-film layer structureAppl. Opt.200941799803

S. W. Kim and G. H. KimThickness-profile measurement of transparent thin-film layers by white-light scanning interferometryAppl. Opt.19993859685973

Y. M. Hwang, S. W. Yoon, J. H. Kim, S. Kim, and H. PahkThin-film thickness profile measurement using wavelet transform in wavelength-scanning interferometryOpt. Lasers Eng.200846179184

D. MansfieldThe distorted helix: thin film extraction from scanning white light interferometryProc. SPIE2006618661860O

D. MansfieldExtraction of film interface surfaces from scanning white light interferometryProc. SPIE20087101797978

B. Maniscalco, P. M. Kaminski, and J. WallsThin film thickness measurements using scanning white light interferometryThin Solid Films20145501016

D. S. Kim and S. H. KimFast thickness profile measurement using a peak detection method based on an acousto-optic tunable filterMeas. Sci. Technol.200213L1L5

J. W. You, S. Kim, and D. KimHigh speed volumetric thickness profile measurement based on full-field wavelength scanning interferometerOpt. Express2008162102221031

T. Jo, K. Kim, S. R. Kim, and H. J. PahkThickness and surface measurement of transparent thin-film layers using white light scanning interferometry combined with reflectometryJ. Opt. Soc. Korea201418236243

H. G. Tompkins and W. A. McGahanSpectroscopic ellipsometry and reflectometry: a user’s guideJohn Wiley & Sons INNew York1999821

K. G. LarkinEfficient nonlinear algorithm for envelope detection in white light interferometryJ. Opt. Soc. Am. A.199613832843

P. de Groot and L. DeckThree-dimensional imaging by sub Nyquist sampling of white -light interferogramsOpt. Lett.19931814621464

J. Schwider, R. Burow, K.-E. Elssner, J. Grzanna, R. Spolaczyk, and K. MerkelDigital wave-front measuring interferometry: some systematic error sourcesAppl. Opt.19832234213432

K. ItohAnalysis of the phase unwrapping problemAppl. Opt.19822124702470

S. R. Kim, J. H. Kim, and H. J. PahkFringe-order determination method in white-light phase-shifting interferometry for the compensation of the phase delay and the suppression of excessive phase unwrappingJ. Opt. Soc. Korea201317415422

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