Dark field double dipole lithography (DDL) for 45nm node and beyond

Abstract

Extending ArF lithography to the 45nm node at a lower k 1 puts a heavy demand on resolution enhancement techniques (RETs), exposure tools, and lithography friendly design. Hyper numerical aperture (NA) exposure tools, immersion [1], and double exposure techniques (DETs) are promising methods to extend lithography manufacturing to the 45nm node at k 1 factors around 0.3. Double dipole lithography (DDL) is becoming a popular RET candidate for foundries and memory makers to pattern the poly gate active layer [2, 3, 4]. Double exposure method or double pattern technique (DPT), [5, 6, 7] using ternary 6% attenuated PSM (attPSM) is a good imaging solution that can reach and likely go beyond the 45nm node. In this work, back end of the line (BEOL) metal like test structures were used for developing a model-based dark field DDL method. We share our findings of using DDL for patterning 45nm node trench structures with binary intensity mask (BlM) on a dry high NA ArF scanner.