Although many block copolymer (BCP) systems are suitable for nanopatterning applications, lamellar BCPs capable of forming perpendicular 5 nm features are especially valuable because the feature sizes naturally produced by these materials rival the resolution of the most advanced patterning processes used in semiconductor manufacturing today. By pushing the limits of chemical incompatibility between polymer blocks, we have recently demonstrated the self-assembly of 5 nm line/space patterns in thin films using poly(5-vinyl-1,3-benzodioxole-block-pentamethyldisilylstyrene) (PVBD-b-PDSS, L0 = 10 nm). When assembled on top of guiding structures patterned by nanoimprint lithography (NIL), highly ordered 5 nm BCP lamellae were produced over large areas. This approach combines chemo- and grapho-epitaxy directed self-assembly (DSA) processes with thermal annealing to produce aligned BCP structures. The cross-linked NIL resist structures were modified by plasma etching prior to BCP deposition, and systematic variation of the height of the NIL guidestripes demonstrated that topography plays an important role in promoting defect-free self-assembly. Cross-sectional analysis using STEM and electron energy loss spectroscopy (EELS) revealed key process parameters responsible for promoting vertical through-film structures. To fabricate relevant structures for microelectronics applications, sophisticated etching techniques were developed to selectively remove one block and produce high aspect ratio etch masks from the initial BCP film. The resulting 5 nm structures could be then transferred into an underlying film by a subsequent reactive ion etching (RIE) process. These results represent a significant advancement for demanding patterning applications such as fabricating high areal density NIL templates for bit-patterned media.

Directed self-assembly of 5 nm block copolymer lamellae enabled by nanoimprint lithography

253rd National Meeting (2017)

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