28 September 2017 Pattern sampling for etch model calibration
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Proceedings Volume 10446, 33rd European Mask and Lithography Conference; 1044610 (2017) https://doi.org/10.1117/12.2279700
Event: 33rd European Mask and Lithography Conference, 2017, Dresden, Germany
Successful patterning requires good control of the photolithography and etch processes. While compact litho models, mainly based on rigorous physics, can predict very well the contours printed in photoresist, pure empirical etch models are less accurate and more unstable. Compact etch models are based on geometrical kernels to compute the litho-etch biases that measure the distance between litho and etch contours. The definition of the kernels as well as the choice of calibration patterns is critical to get a robust etch model. This work proposes to define a set of independent and anisotropic etch kernels –“internal, external, curvature, Gaussian, z_profile” – designed to capture the finest details of the resist contours and represent precisely any etch bias. By evaluating the etch kernels on various structures it is possible to map their etch signatures in a multi-dimensional space and analyze them to find an optimal sampling of structures to train an etch model. The method was specifically applied to a contact layer containing many different geometries and was used to successfully select appropriate calibration structures. The proposed kernels evaluated on these structures were combined to train an etch model significantly better than the standard one. We also illustrate the usage of the specific kernel “z_profile” which adds a third dimension to the description of the resist profile.
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François Weisbuch, François Weisbuch, Andrey Lutich, Andrey Lutich, Jirka Schatz, Jirka Schatz, } "Pattern sampling for etch model calibration", Proc. SPIE 10446, 33rd European Mask and Lithography Conference, 1044610 (28 September 2017); doi: 10.1117/12.2279700; https://doi.org/10.1117/12.2279700

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