Novel negative photoresist process for 0.18 μm dual damascene

Abstract

A great deal of progress has been made in the design of dual damascene process, including via first, trench first, and self aligned. For overlay, via-first process provides the largest process tolerance to misalignment. However, the positive tone resist face to some difficulties in dual damascene via first approach of photo process, because the th 18 um positive tone trench resist can not exposed and removed in the O2O urn via hole, observed residues from the SEM cross section profiles after development. In contrast, the negative tone resist shows great advantage in the via first process and producing desired patterns without resist residues in the via hole. In this paper, the design of dual damascene photo process using coniniercial N702Y (JSR) negative tone resist on DUV42 (Brewer Sc.) bottom anti reflective coating is evaluated. To improve the depth of focus (DOF) of negative tone resist process, the different resolution enhancement techniques (RET) are investigated for dense and isolated trench patterns: offaxis illumination (annular 1/2), attenuated phase shift mask (halftone 6%) with 248nm (NA 0.55) exposure technology, and experimental results regarding to its process performance are presented.