The modeling of double patterning lithographic processes

Abstract

Double patterning (DP) appears to be the most probable patterning technology for initial 32 nm node manufacturing. This work explores how it may be accurately simulated. In the first instance, the process is approximated using two planar exposures in a commercial lithographic simulation package. This work is then followed up by more accurate calculations using a prototype simulator (based of Rigorous Coupled Wave Analysis propagation techniques) which allows the topography generated from the first exposure pass to influence the light propagation in the second exposure. The accuracy of the prototype simulator is demonstrated by validating its' output against the vector model in PROLITH V10, for the planar topography case. Results from the RCWA simulations show that for an example poly gate double patterning process, the presence of the topography enhances the process window of the second exposure, in terms of both exposure and focus latitude. The topography simulator is also used to study the robustness of the second exposure process window to fluctuations in the CD printed during the first exposure pass and of the influence of misalignment between the two passes.

Rigorous electromagnetic field simulation of two-beam interference exposures for the exploration of double patterning and double exposure scenarios

“…Both effects contribute to a smaller linewidth (CD) after the second lithography step compared to the linewidth after the first lithography step over a planar BARC. This impact of hardmask patterning was already observed by Robertson et al [11]. Similar plots for hardmask materials reveal that high refractive index HM materials attract the light and reduce the light intensity in the resist.…”