A Universal Approach to Fabricating 3D Chemical Patterns for Directed Self-Assembly of Block Copolymers with Density Multiplication

Directed self-assembly (DSA) of block copolymers (BCPs)with densitymultiplication has been proved to be a viable technique for the fabricationof FinFET at the 7 nm node. The key to the realization of DSA withdensity multiplication is to control the interfacial energy betweenBCP and the underlying substrate. In this work, we report a universaland fab-compatible approach to fabricating 3D chemical patterns forDSA of BCPs with density multiplication by combining lithographicpatterning and plasma treatment. The surface energy of cross-linkedpolystyrene (XPS) mat could be tuned for controlling the wetting behaviorof BCP films by simply adjusting oxygen plasma treatment conditions.Non-preferential surfaces for poly (styrene-b-methylmethacrylate) (PS-b-PMMA), poly (styrene-b-methyl acrylate) (PS-b-PMA), poly (styrene-b-propylene carbonate) (PS-b-PPC), andpoly (styrene-b-(lactic acid-alt-glycolic acid))(PS-b-PGLA) are obtained by oxygen plasma treatment,which eliminates the use of random copolymer brushes in the LiNe flow.3D chemical patterns are successfully fabricated by combining e-Beampatterning of PMMA photoresist and oxygen plasma treatment, and DSAof lamellae-forming PS-b-PMMA and PS-b-PMA with up to 10x density multiplication is achieved on 3D chemicalpatterns.