Optical imaging is traditionally carried out using circular pupils, assuring the absence of orientation dependency. In the case of IC microlithography however, such dependency exists and is generally limited to orthogonal axes. We have previously reported the potential improvement to lithographic imaging through the use of a square character to an illumination pupil using fully open pupils, square rings, and slot shapes. In this paper we show lithographic results for this shaping at 193nm using a full field (ASML) imaging tool. Results show improvement in both DOF and exposure latitude over conventional circular shaping, leading to the consideration of this approach as a manufacturable method of resolution enhancement.
Date of creation, presentation, or exhibit
Department, Program, or Center
Microelectronic Engineering (KGCOE)
Bruce W. Smith, Geert Vandenberghe, "Image enhancement through square illumination shaping", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474535; https://doi.org/10.1117/12.474535
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