Evaluation of extendibility for Fourier diffraction theory for topographical mask structure under hyper NA lithography

Satoshi Tanaka; Akiko Mimotogi; Soichi Inoue

doi:10.1117/12.600447

12 May 2005 Evaluation of extendibility for Fourier diffraction theory for topographical mask structure under hyper NA lithography

Satoshi Tanaka, Akiko Mimotogi, Soichi Inoue

Author Affiliations +

Proceedings Volume 5754, Optical Microlithography XVIII; (2005) https://doi.org/10.1117/12.600447
Event: Microlithography 2005, 2005, San Jose, California, United States

Abstract

Recent progress of immersion lithography technique could realize to apply hyper NA condition for real IC device manufacturing. Under the hyper NA lithography, we have to face the paradigm shift from scalar treatment to vector consideration in the region of modeling everywhere. In the historical view points, vector lithographic imaging model was introduced in 1986¹, and the beginning of 90’s, various evaluation works were reported in the field. And the research or evaluation of topographical mask effects were also focused and concentrated the same era using rigorous electromagnetic simulations^2-4. But as for the “oblique illumination effects” at a reticle side, much concerns had not been paid about them. It was because the relaxation of incident angle due to magnification factor (4X or 5X), using small σ for alternating phase-shifting mask, and higher NA seemed to work worse as for decreasing DOF. Since the immersion lithography technique would be considered as “effective reduction of exposure wavelength by factor of the refraction index of immersion material” and superior DOF characteristics to the dry case, development of increasing exposure tool’s NA beyond 1.0 have been accelerated. In such a hyper NA region, we have to consider about the “oblique illumination effects” once again for various fields, such as combining to the model-based OPC application and so on. In this paper, 1^st order approximation model is suggested and evaluated how much degree of influence of the oblique illumination effects should be taken care of, and how large area could be covered using this model. The former results denoted that around 10% of target CD might be varied in the case of hyper NA condition. But from the latter results, we did not sufficient validity for this model, so some additional approximation should be considered to improve the prediction accuracy.

Citation Download Citation

Satoshi Tanaka, Akiko Mimotogi, and Soichi Inoue "Evaluation of extendibility for Fourier diffraction theory for topographical mask structure under hyper NA lithography", Proc. SPIE 5754, Optical Microlithography XVIII, (12 May 2005); https://doi.org/10.1117/12.600447

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