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Jeudi 19 Septembre 2013

14 heures - Bibliothèque du CRMD

Block copolymers as an alternative solution for advanced lithography in sub-16nm technology nodes

Ahmed Gharbi - CEA-LETI

The standard optical lithography has shown its limitations for the most advanced technologies nodes in VLSI circuits (sub-16nm) since it can only reach a resolution of 40 nm half-pitch. Among different emerging patterning approaches, block copolymers (BCP) offer an attractive solution for the next generation device fabrication [1,2]. Indeed, due to their self-assembly properties and their different accessible morphologies (lamellar, cylindrical…), those macromolecular systems allow for the generation of very high-resolution nanodomains with critical dimension (CD) and pitch down to 10nm and 20nm, respectively. These nanodomains can be precisely oriented on different kinds of substrates by surface energy modification. Furthermore, they can be finely placed at desired locations with lithographically predefined templates (so called directed self-assembly (DSA) process by graphoepitaxy).

Using the DSA pilot line available in LETI and Arkema’s materials, our approach is based on the graphoepitaxy of PS-b-PMMA block copolymers. In this paper, we demonstrate the potential of the DSA process to achieve a long range order of block copolymer nanostructures in their natural hexagonal configuration (see figure 1a). When extern constrains are controlled in two directions, complex configurations can be obtained and hexagonal symmetry of BCP is broken, as depicted in figure 1b. Furthermore, we report shrinking of lithographically defined contact holes (figure 1c). The detailed process flow associated with these different approaches is described and discussed considering different parameters such as the BCP film thickness, the self-assembly annealing, the guiding template size, pitch and density. Finally, the etch transfer of BCP patterns to the underlying substrate using the PS template after the selective removal of the PMMA block is demonstrated. High-resolution contact holes (CD down to 15nm after transfer) of high aspect ratio are achieved without defects and with good CD uniformity.


1. J. Y. Cheng et al., ACS Nano, 4(8), 4815-23 (2010)
2. R. Tiron et al., Proc. of SPIE 2012, 8323-23