Fabrication of 0.1 µm Patterns Using an Alternating Phase Shift Mask in ArF Excimer Laser Lithography

We demonstrate applications of alternating phase shift mask (Alt-PSM) techniques to ArF excimer laser lithography with a numerical aperture of 0.6 and a coherence factor of 0.3. A 0.10 µm line-&-space (L/S) pattern was fabricated using a single-layer resist and a 0.09 µm L/S pattern was fabricated using a silylation resist. However, the process window was smaller for the silylation resist than for the single-layer resist over the 0.10–0.13 µm L/S range. The maximum depth of focus (DOF) values were approximately 0.3, 0.5, and 0.9 µm for 0.10, 0.11, and 0.13 µm L/S patterns, respectively, for the single-layer resist. From exposure dose-DOF-tree analysis, we estimated the inclusive process margin including the critical dimension difference, the DOF, the dose margin, and the phase error. Assuming that the usable DOF is larger than 0.5 and 0.6 µm for 0.11 and 0.13 µm L/S patterns, respectively, the inclusive process margin for the single-layer resist is poor in comparison with future predictions.