The goal of this paper is to investigate the potential of Directed Self-Assembly (DSA) to address
contact via level patterning, by either Critical Dimension (CD) shrink or contact multiplication. Using the
300mm pilot line available in LETI and Arkema materials, our approach is based on the graphoepitaxy of PS-b-
PMMA block copolymers (BCP). The process consists in the following steps: a) the lithography of guiding
patterns, b) the DSA of block copolymers and PMMA removal and finally c) the transfer of PS patterns into the
under-layer by plasma etching.
Several integration schemes using 193nm dry lithography are evaluated: negative tone development
(NTD) resists, a tri-layer approach, frozen resists, etc. The advantages and limitations of each approach are
reported. Furthermore, the impact of the BCP on the final patterns characteristics is investigated by tuning
different parameters such as the molecular weight of the polymeric constituents and the interaction with the
substrate. The optimization of the self-assembly process parameters in terms of film thickness or bake
(temperature and time) is also reported. Finally, the transfer capabilities of the PS nanostructures in bulk silicon
substrate by using plasma-etching are detailed.
These results show that DSA has a high potential to be integrated directly into the conventional CMOS
lithography process in order to achieve high-resolution contact holes. Furthermore, in order to prevent design
restrictions, this approach may be extended to more complex structures with multiple contacts and nonhexagonal