ANALYSIS OF SUB-0.15 MU-M PATTERN REPLICATION IN SYNCHROTRON-RADIATION LITHOGRAPHY

An absorber profile is essential when replicating deep quarter-micron patterns because of the X-ray phase-shifting effect in the absorber. We have compared experimental results of 0.15 mum line-and-space (L/S) pattern with calculation based on Fresnel diffraction using the measured absorber profile and resist property. The experimental mask had a beveled absorber edge profile, and the 0.15 mum L/S exposure latitude values obtained with this mask are +/- 6% for a 30 mum gap, +/- 8% for 20 mum, and +/- 12% for 10 mum. The calculation showed good coincidence with respect to the dependence of the latitude on the gap, but the calculated pattern size is about 0.05 mum less than the experimental one. Simulation on the 0.1 mum L/S printability was further carried out for a 20 mum gap. Although the applied exposure dose was rather small, the pattern was resolved by the beveled-edge mask with a mask contrast of about 6.