Gratings of regular arrays and trim exposures for ultralarge scale integrated circuit phase-shift lithography

• Published in: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 2001-11, Vol.19 (6), p.2366-2370
• Main Authors: Fritze, M., Tyrrell, B., Astolfi, D., Yost, D., Davis, P., Wheeler, B., Mallen, R., Jarmolowicz, J., Cann, S., Chan, D., Rhyins, P., Carney, C., Ferri, J., Blachowicz, B. A.
• Format: Article
• Language: English
• Subjects: Diffraction gratings; Image analysis; Image enhancement; Imaging techniques; Scanning electron microscopy; ULSI circuits
• ISSN: 0734-211X; 1071-1023; 1520-8567
• DOI: 10.1116/1.1408950

Current semiconductor technology requires optical lithography to image feature sizes smaller than the exposure tool wavelength. In order to achieve this subwavelength imaging, some form of optical resolution-enhancement technology is required, with phase-shift methods offering the greatest potential enhancement. Major impediments to the wide-scale adoption of this technology have included mask cost, inspectability/repair, and turnaround time. The correction of optical proximity effects, which are typically large in phase-shift techniques, have also been an important issue. In this work, we propose a new type of phase-shift approach utilizing gratings of regular arrays and trim exposures. This method makes use of multiple-exposure phase-shift imaging of dense-only features. Proximity effects can be nearly eliminated along with the complex optical proximity corrections typically required on the mask. The simple phase-shift masters can also be reused for multiple designs, thereby addressing cost and turnaround time issues.