Lithography mask having sub-resolution phased assist features

摘要

Techniques are disclosed for using sub-resolution phased assist features (SPAF) in a lithography mask to improve through process pattern fidelity and/or mitigate inverted aerial image problems. The technique also may be used to improve image contrast in non-inverted weak image sites. The use of SPAF in accordance with some such embodiments requires no adjustment to existing design rules, although adjustments can be made to enable compliance with mask inspection constraints. The use of SPAF also does not require changing existing fab or manufacturing processes, especially if such processes already comprehend phased shift mask capabilities. The SPAFs can be used to enhance aerial image contrast, without the SPAFs themselves printing. In addition, the SPAF phase etch depth can be optimized so as to make adjustments to a given predicted printed feature critical dimension.

主权项

1. A lithography mask for fabricating semiconductor circuits, comprising:
a main feature having a phase and a polarity; and a sub-resolution phased assist feature (SPAF) having a polarity that is the same as the polarity of the main feature and a phase that is 155° to 205° out-of-phase with the phase of the main feature.