Journal of Vacuum Science & Technology B, Vol.19, No.6, 2366-2370, 2001
Gratings of regular arrays and trim exposures for ultralarge scale integrated circuit phase-shift lithography
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 alone, 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.