Block copolymers offer an appealing alternative to current lithographic techniques with regard to fabrication of the next generation micro- processors. However, if copolymers are to be useful on an industrial manufacturing scale, they must meet or exceed lithography specifications for placement and line edge roughness (LER) of resist features. Here we discuss a field theoretic approach to modeling the LER of lamellar microdomain interfaces in a strongly segregated block copolymer system; specifically, we derive formulas for the LER and sidewall angle variation (SAV) as functions of the Flory Huggins parameter χ and the index of polymerization N . Our model is based on the Leibler- Ohta-Kawasaki energy functional. We consider a system with a finite number of phase separated microdomains and also show how the LER depends on distance of the microdomain interface from the system boundary. Our results suggest that in order to meet target LER goals at the 15, 11, and 6 nm nodes, χ must be increased by a factor of at least 5 above currently attainable values.
Citation: Proceedings of SPIE
Pub Type: Journals
block copolymers, line edge roughness, directed self assembly, phase field model