193 nm resist shrinkage carryover effect to a post-etch layer due to CD-SEM measurement

摘要

193 nm resist shrinkage due to critical dimension scanning electron microscope (CD-SEM) measurements is a well-known but unresolved metrology issue in microlithography. Although there have been numerous studies on this subject, there are few publications on the 193 nm resist shrinkage finger-print carried over to etched features, i.e., the CD shrinkage carryover effect. This paper reports the results of our CD-SEM measurement study. We observed that the CD changes due to measurement were still present after etch and were often greater than 15% of the feature size. The shrinkage result implies that the action of CD-SEM measurement is destructive to the patterned circuitry. An improved CD-SEM measurement methodology is required to reduce circuitry damage. The study also revealed that minimal shrinkage carryover (less than 1%) could be obtained when the CD-SEM measurement condition was optimized. These results also indicate that measurement of CD shrinkage on post-etch patterns can offer a very effective method to characterize pre-etch resist shrinkage.