Improvement of photomask repeater for 130-nm lithography

Device masks for 180nm lithography was fabricated by PR system. These masks were verified by device yields comparing with masks written by other conventional systems. There were no differences in device yields between PR system and conventional system. Fine analysis of CD error was carried out for enhancement of CD uniformity to apply Photomask Repeater to 130nm lithography. It revealed that major CD error function is global CD error. By optimizing exposure dose of each shot to compensate global distribution, global CD error was reduced from 7.9nm to 5.5nm. Finally, CD uniformity of 8nm was achieved. PR system can afford to fulfill the requirement of CD uniformity for 130nm lithography. Simultaneously, the result of fine analysis indicates excellence of PR system in littleness of random error.