Optimization of Dual-BARC Structures on Silicon Oxide and Nitride Layers to be Used for Hyper NA Immersion Lithography

Abstract

For the purpose of identifying dual-BARC (Bottom Anti-Reflective Coating) structures for immersion lithography that do not depend on the polarization of light, illumination conditions and pattern sizes or pitches, dual-BARC parameters were optimized. Using our new code, dual-BARC parameters to minimize the substrate reflectance were obtained for BARC formed on a silicon oxide and nitride layer when NA is 1.0, 1.1, 1.2, 1.3 and 1.4. The thickness of the silicon oxide and nitride layer was varied from 10 to 200 nm. It was found that the dual-BARC concept works up to NA = 1.1 and 1.4 for BARC on a silicon oxide and a silicon nitride layer, respectively, although for the case of the dual BARC on a silicon oxide layer, the range of the thickness of the oxide layer where the dual-BARC concept works is limited. It was also found that using a structure consisting of a planarization layer combined with a single-layer BARC structure to make a reflection-control structure can work up to NA = 1.4 for both on a silicon oxide and nitride layer.