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

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, 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. Double exposure method or double pattern technique (DPT), 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 (BIM) on a dry high NA ArF scanner.