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Measuring Local Strain Variations Full-Field in Photoresist Thin Films Using Photolithographic Dot Arrays

Published online by Cambridge University Press:  10 February 2011

P.P. Lin  and
R. E. Rowlands
P.P. Lin
Affiliation:
Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706
R. E. Rowlands
Affiliation:
Materials Science Program, University of Wisconsin-Madison, Madison, WI 53706
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Abstract

Photoresist (such as PMMA) thin films are among the most important materials in semiconductor fabrication processes. Photolithography exclusively uses photoresist to construct the circuit pattern. The quality of a pattern relies on the uniformity of a photoresist layer. However, thermal expansion mismatch between the photoresist and silicon substrate during the subsequent thermal cycling process inevitably produces undesirable residual strains/stresses in the resist layer. Such residual fields can deteriorate the desired quality of the final pattern. A recently developed method is used here to record full-field strain information in the thin resist film.

Traditional methods such as wafer curvature measurement or x-ray diffraction (for crystalline films) have not been effective for measuring the full-field strains. However, using a deposited dot array in the interface between the film and substrate, one can measure the strains in the thin film, full-field, by analyzing the displacements of individual dots. A biquadratic surface model is employed to fit these dot pattern displacements. An IDL (Interactive Data Language, Research Systems Inc.) program is utilized repeatedly to accurately locate the positions of the individual dots and transform that information into displacement and strain data by differentiating the biquadratic surface. This study successfully demonstrates a straightforward approach to determine the residual strains, full-field, in photoresist thin films.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 516: Symposium E – Low Dielectric Constant Materials IV , January 1998 , 261
Copyright
Copyright © Materials Research Society 1998

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References

1. Fail, R.W. and Taylor, C. E., “An Application of Pattern Mapping to Plane Motion”, Exp. Mech., vol.30, p.404–410, (1990).10.1007/BF02321512Google Scholar
2. Sirkis, J. S. and Lim, T. J., “Displacement and Strain Measurement with Automated Grid Methods”, Exp. Mech., vol.31, p.382–388, (1991).10.1007/BF02325997Google Scholar
3. Wissuchek, D. J., Mackin, T. J., DeGraef, M., Lucas, G. E., and Evans, A. G., “A Simple Method For Measuring Surface Strains Around Cracks”, Exp. Mech., p.173–179, June, (1996).Google Scholar
4. Dally, J. W. and Riley, W. F., Experimental Stress Analysis, 3rd ed. (McGraw Hill, Inc., New York, 1991), p.542.Google Scholar
5. Schweitz, J-A, “Mechanical Characterization of Thin Films by Micromechanical Techniques”, Materials Research Society Bulletin (Mater. Res. Soc., Pittsburgh, PA, July 1992) p.34–45.Google Scholar
6. Callister, W.D. Jr, Materials Science and Engineering: An Introduction, 4th edition (John Wiley and Sons, New York, 1997), Appendix C, p.777–790.Google Scholar