CD controllability evaluation based on process error distribution for 150-nm devices

The design rule of ULSI devices is now approaching the 150 nm region, and highly accurate critical dimension (CD) control is required. Due to the delay of the development of ArF resists and exposure tools, KrF lithography is considered as the most promising technology for 150 nm devices. Since the imaging performance for such a small feature size is not sufficient in KrF lithography, higher NA lenses with higher resolution are necessary. However, the problem is that as the NA becomes higher, it generally becomes much more difficult and takes a longer period to design and manufacture a projection lens with small aberrations in the full exposure field. In this study, we investigate the influences of various error factors on CD fluctuation and discuss the CD controllability of 150 nm patterns, focusing on the effects of high NA KrF exposure.