Performance characterization of negative resists for sub-10-nm electron beam lithography

As scaling continues, the need for reliable sub-10-nm electron beam lithography is apparent. Throughput is a major drawback and complex test structure fabrication would be constrained by practical limits on writing time. A major challenge for sub-10-nm patterning with electron beam lithography is tool and process efficiency especially for high sensitivity resists. This article presents current work done at the College of Nanoscale Science and Engineering where the authors investigated three different commercially available resist systems, namely, SU-8, NEB-31, and HSQ, which have a range of sensitivity from close to the shot noise limit to slow material with high resolution. The authors present the results obtained from these resists with their respective critical dimension, line edge roughness (LER), and line width roughness (LWR) values that correlate with sensitivity and are consistent with the well known resolution, line edge roughness, sensitivity trade-off. Due to the inability of tools to deliver low doses at step sizes close to grid size limit of the tool, the ultimate resolution limit of SU-8 and NEB-31 with acceptable LER and LWR is yet to be determined.