Temperature dependent effective process blur and its impact on exposure latitude and lithographic targets using e-beam simulation and proximity effect correction

It is well known that cold development yields higher contrast and improved exposure latitude particularly for ZEP520 from Zeon Chemicals. In this paper, the authors quantify the effective process blur as a function of temperature. The effective process blur for our development process conditions were found to be 10, 42, and 71nm for developer temperatures at -12, 21, and 30°C, respectively. Knowledge of how to tune the process blur can be used in a unique application. Instead of using the best possible process blur, exposure latitude is traded for improved exposure time. Optimizing the e-beam exposure time is always desired while maintaining a target critical dimension and desired shape at the wafer. In particular, the exposure time can be dominated by shape overhead delays stemming from the over digitization of curved shapes within a pattern. As such, it is better to expose a pattern with the least number of shapes as possible while obtaining the desired shape at the wafer. The authors demonstrate how e-beam simulation can be used to determine the optimal effective process blur to obtain a target desired shape while minimizing the fractured shape count to ultimately reduce overall exposure time.