Efficiently writing circular contacts on production reticle

Aki Fujimura; Christophe Pierrat; Taiichi Kiuchi; Tadashi Komagata; Yasutoshi Nakagawa

doi:10.1117/12.866412

26 May 2010 Efficiently writing circular contacts on production reticle

Aki Fujimura, Christophe Pierrat, Taiichi Kiuchi, Tadashi Komagata, Yasutoshi Nakagawa

Proceedings Volume 7748, Photomask and Next-Generation Lithography Mask Technology XVII; 77481P (2010) https://doi.org/10.1117/12.866412
Event: Photomask and NGL Mask Technology XVII, 2010, Yokohama, Japan

Abstract

As we prepare for 32nm-hp with 193nm immersion, complex and sometimes curvilinear shapes are going to be required on masks. Contacts and vias will be circular or oval in shape on the wafer, but are still drawn as over-sized squares or rectangles on masks and in CAD systems. Yet, for packing density of designs, particularly for DRAMs and SRAMs, in order to optimize for diagonal distances, a circular via shape on the mask is desirable. In addition, a circle has by definition the minimum perimeter for a given area, improving manufacturing tolerance. This paper demonstrates new techniques for writing circles of arbitrary diameters on masks efficiently and accurately using a production e-beam mask writer. Resist-exposed SEM images are shown, demonstrating the practicality of writing circles as mask shapes for production reticles.

Citation Download Citation

Aki Fujimura, Christophe Pierrat, Taiichi Kiuchi, Tadashi Komagata, and Yasutoshi Nakagawa "Efficiently writing circular contacts on production reticle", Proc. SPIE 7748, Photomask and Next-Generation Lithography Mask Technology XVII, 77481P (26 May 2010); https://doi.org/10.1117/12.866412

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