DUV-assisted E-beam Resist Process

Electron beam direct writing (EBDW) resist process is slow in throughput but has the highest linewidth resolution among all the lithography techniques. However the e-beam energy is high enough to cut off the polymer chain of DUV chemically amplified resist (CAR) and thus in this paper, DUV-assisted e-beam resist process is studied to increase throughput. The C/H critical dimension (CD) with e-beam exposure only increases for larger dose. E-beam dose-to-size of C/H is found to be independent on pattern density. The smallest CD resolved is 30.2 nm for 30 nm designed CD. DUV pre-exposed resist resolves the same C/H CD size with lower e-beam dose. Largest e-beam dose reduction with DUV-assistance is similar to 40% for 50 and 70 nm designed CD of C/Hs. BARC coating and multiple DUV pre-exposures with variable depths are studied for obtaining a vertical profile like that exposed by e-beam only.