22 March 2012 Analytical treatment of the deformation behavior of EUVL masks during electrostatic chucking
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Abstract
A new analytical approach is presented to predict mask deformation during electro-static chucking in next generation extreme-ultraviolet-lithography (EUVL). Given an arbitrary profile measurement of the mask and chuck non-flatness, this method has been developed as an alternative to time-consuming finite element simulations for overlay error correction algorithms. We consider the feature transfer of each harmonic component in the profile shapes via linear elasticity theory and demonstrate analytically how high spatial frequencies are filtered. The method is compared to presumably more accurate finite element simulations and has been tested successfully in an overlay error compensation experiment, where the residual error y-component could be reduced by a factor 2. As a side outcome, the formulation provides a tool to estimate the critical pin-size and -pitch such that the distortion on the mask front-side remains within given tolerances. We find for a numerical example that pin-pitches of less than 5 mm will result in a mask pattern-distortion of less than 1 nm if the chucking pressure is below 30 kPa.
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Gerd Brandstetter, Gerd Brandstetter, Sanjay Govindjee, Sanjay Govindjee, } "Analytical treatment of the deformation behavior of EUVL masks during electrostatic chucking", Proc. SPIE 8322, Extreme Ultraviolet (EUV) Lithography III, 832210 (22 March 2012); doi: 10.1117/12.916530; https://doi.org/10.1117/12.916530
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