Fringe 2005 pp 622-631 | Cite as
Challenges in the dimensional Calibration of submicrometer Structures by Help of optical Microscopy
Conclusion
A basic task in dimensional metrology is edge localisation. The distance of two neighboring edges in an object structure, for instance, can be determined by the evaluation of the intensity distribution by use of threshold or extreme-value criteria. However, the distributions in the images begin to overlap for structures with dimensions below λ/NA where λ is the wavelength and NA is the numerical aperture of the imaging lens. That’s why the distances of the extreme values or the thresholds become strongly dependent from the width of the structures and for still smaller structures the extrema usually merge into one extremum.
By use of a special new type of dark field illumination it becomes possible to separate the maxima of intensity representing the edges of single microstructures whose edges would not be resolved by conventional dark field techniques. But also with this method the position of the extreme values in the image distribution has an offset to the true positions of the structure edges. In order to get traceable measurements; however, modelling of the image intensity on the basis of rigorous diffraction theories can be applied in order to compensate for residual offsets from exact edge positions [23]. The most direct connection of the length scale of a measuring microscope is achievable by making use of the object scanning method [24] where the object stage of the system is equipped with a laser interferometer.
Keywords
Optical Sensor Dark Field Bright Field Imaging Dark Field Imaging Edge LocalisationPreview
Unable to display preview. Download preview PDF.
References
- 1.Hopkins, H. H (1953) On the diffraction theory of optical images. Proc. Roy. Soc. Lond. A 217: 408–432MATHMathSciNetCrossRefGoogle Scholar
- 2.Pluta, M (1989) Advanced Light Microscopy, Vol. 2, Specialized Methods. PWN-Polish Scientific Publishers Warzawa 494 pagesGoogle Scholar
- 3.Totzeck, M, Jacobsen, H, Tiziani, H. J (2000) Edge localisation of subwavelength structures by use of interferometry and extreme-value criteria. Applied Optics 39: 6295–6305CrossRefGoogle Scholar
- 4.Bodermann, B, Michaelis, W. Diener, A, Mirandé, W. (2003) New Methods for Measurements on Photomasks using dark field optical Microscopy. Proc. of 19th European Mask Conference on Mask Technology for Integrated Circuits and Micro-Components, GMM-Fachbericht 39: 47–52Google Scholar
- 5.Nyysonen, D, Larrabee, R (1987) Submicrometer Linewidth Metrology in the Optical Microscope. J. Research of the National Bureau of Standards, Vol.16Google Scholar
- 6.Potzick, J. (1989) Automated Calibration of Optical Photomask Linewidth Standards at National Institute of Standards and Technology. SPIE Symposium on Microlithography 1087: 165–178Google Scholar
- 7.Czaske, M, Mirandé, W, Fraatz, M (1991) Optical Linewidth Measurements on Masks and Wafers in the Micrometre and Submicrometre Range. Progress in Precision Engineering: 328–329Google Scholar
- 8.Nunn, J. Mirandé, W. Jacobsen, H. Talene, N (1997) Challenges in the calibration of a photomask linewidth standard developed for the European Commission. GMM-Fachbericht 21: 53–68Google Scholar
- 9.Lesssor, D. L. Hartmann, J.S. and Gordon, R.L. (1979) Quantitative Surface Topography determination by Nomarski Reflection Microscopy, I. Theory. J Opt. Soc. Am. 69: 22–23Google Scholar
- 10.Kimura, S. Wilsom, T. (1994) Confocal scanning dark-field polarization microscopy. Applied Optics 33: 1274–1278CrossRefGoogle Scholar
- 11.ISO, Geneva (1993) International Vocabulary of Basic and General Terms in Metrology. 2nd EditionGoogle Scholar
- 12.ISO, Geneva (1993) Guide to the Expression of Uncertainty in Measurement. 1st EditionGoogle Scholar
- 13.Bureau International des Poids et Mesures (1991) Le Système International d’Unitées (SI), 6 ieme ÉditionGoogle Scholar
- 14.Nyyssonen, D (1977) Linewidth Measurement with an Optical Microscope.the Effect of Operating Conditions on the Image Profile. Applied Optics 16: 2223–2230CrossRefGoogle Scholar
- 15.Downs, M. J, Turner, N. P, King, R. J, Horsfield, A (1983) Linewidth Measurements on Photomasks using Optical Image-shear Microscopy. Proc. 50th PTB-Seminar Micrometrology PTB-Opt-15: 24–32Google Scholar
- 16.Mirandé, W. (1983) Absolutmessungen von Strukturbreiten im Mikrometer-bereich mit dem Lichtmikroskop. Proc. 50th PTB-Seminar Micrometrology PTB-Opt-15: 3–16Google Scholar
- 17.Bodermann, B, Mirandé, W (2003) Status of optical CD metrology at PTB. Proc. 188th PTB-Seminar, PTB-Bericht F-48: 115–129Google Scholar
- 18.Hourd, A. C et al. (2003) Implementation of 248 nm based CD Metrology for Advanced Reticle Production. Proc. of 19th European Mask Conference on Mask Technology for Integrated Circuits and Micro-Components, GMM-Fachbericht 39: 203–212Google Scholar
- 19.Hübner, U et al. (2003) Downwards to metrology in naonscale: determination of the AFM tip shape with well known sharp-edged calibration structures.Appl.Phys.A 76: 913–917CrossRefGoogle Scholar
- 20.Hübner, U et al. (2005) Prototypes of nanoscale CD-Standards for high resolution optical microscopy and AFM. Proc. 5th euspen Internatinol ConferenceGoogle Scholar
- 21.Totzeck, M (2001) Numerical simulation of high-NA quantitative polarization microscopy and corresponding near-fields. Optik 112: 399–406Google Scholar
- 22.Miran_é, W, Bodermann. B (2003) New dark field microscopy methods. Proceedings of the 187th PTB-seminar on Current Developments in Microscopy PTB-Opt-68: 73–86Google Scholar
- 23.Schröder, K. P, Mirandé, W, Geuther, H, Herrmann, C (1995) In quest of nm accuracy: supporting optical metrology by rigorous diffraction theory and AFM topograhy. Optics Communications 115: 568–575CrossRefGoogle Scholar
- 24.Mirandé, W. (1990) Strukturbreiten-Kalibrierung und Kontrolle. VDI-Berichte 870: 47–82Google Scholar