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Characterization of Buried Structure in Directed Self Assembly Block Copolymers



Daniel F. Sunday, Matthew R. Hammond, Chengqing C. Wang, Wen-Li Wu, Dean M. DeLongchamp, Regis J. Kline, Melia Tjio, Joy Cheng, Jed W. Pitera


The directed self assembly (DSA) of block copolymers (BCP) can multiply or subdivide the pitch of a lithographically defined chemical or topological pattern and is a resolution enhancement candidate to augment conventional lithography for patterning sub-20 nm features. Continuing the development of this technology will require an improved understanding of the polymer physics involved as well as experimental confirmation of the simulations used to guide the design process. Both of these endeavors will require a metrology which is capable of probing the internal morphology of a DSA film. We have developed a new measurement technique, resonant critical-dimension small angle x-ray scattering (res-CDSAXS), to evaluate the 3D buried features inside the film. This is an x-ray scattering measurement where the sample angle is varied to probe the 3D structure of the film while resonant soft x-rays are used to enhance the scattering contrast. By measuring the same sample with both res-CDSAXS and traditional CDSAXS (with hard x-rays) we are able to demonstrate the dramatic improvement in scattering obtained through the use of resonant soft x-rays. Analysis of the reciprocal space map constructed from the res-CDSAXS measurements allowed us to reconstruct the complex buried features in DSA BCP films. We studied a series of DSA BCP films with varying template widths and the internal morphologies for these samples were compared to the results of single chain in mean-field simulations. The measurements revealed a range of morphologies that occur with changing template width, including results which suggest the presence of mixed morphologies composed of both whole and necking lamella. The development of res-CDSAXS will enable a better understanding of the fundamental physics behind the formation of buried features in DSA BCP films.
ACS Nano


Block copolymer lithography, directed self assembly, small angle x-ray scattering


Sunday, D. , Hammond, M. , Wang, C. , Wu, W. , DeLongchamp, D. , Kline, R. , Tjio, M. , Cheng, J. and Pitera, J. (2014), Characterization of Buried Structure in Directed Self Assembly Block Copolymers, ACS Nano, [online], (Accessed May 24, 2024)


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Created July 30, 2014, Updated November 10, 2018