Lithographically Defined Cross-Linkable Top Coats for Nanomanufacturing with High-χ Block Copolymers

Abstract

The directed self-assembly (DSA) of block copolymers (BCPs) is a powerful method for the manufacture of high-resolution features. Critical issues remain to be addressed for successful implementation of DSA, such as dewetting and controlled orientation of BCP domains through physicochemical manipulations at the BCP interfaces, and the spatial positioning and registration of the BCP features. Here, we introduce novel top-coat (TC) materials designed to undergo cross-linking reactions triggered by thermal or photoactivation processes. The cross-linked TC layer with adjusted composition induces a mechanical confinement of the BCP layer, suppressing its dewetting while promoting perpendicular orientation of BCP domains. The selection of areas of interest with perpendicular features is performed directly on the patternable TC layer via a lithography step and leverages attractive integration pathways for the generation of locally controlled BCP patterns and nanostructured BCP multilayers.

Multifunctional Top-Coats Strategy for DSA of High-χ Block Copolymers

“…1, left) [5]. It presents a large difference in the surface free energy of its blocks, and is able to reach dimensions below 12 nm in period as previously demonstrated [3]. The silicon, present in the PDMSB block, enables to increase the etch performances for the final transfer step into the underlying substrate.…”

“…The synthesis of the TC material was performed by radical polymerization in solution with AIBN as initiator [3]. All the monomers, solvent, initiator and terminating agent were used as received.…”

“…These BCPs necessitate the use of top-coats (TC) materials to balance the interfacial tension between the blocks and achieve the perpendicular orientation of nanometric features [2]. In our previous works we proposed a new design of TCs able to circumvent keys challenges posed by the integration of DSA into microelectronic nodes [3,4]. Here we highlight the specific properties of these TCs enabling their multifunctional use for nano-manufacturing.…”

Dry-Etching Processes for High-Aspect-Ratio Features with Sub-10 nm Resolution High-χ Block Copolymers

“…Nevertheless, this is only a minor drawback considering the demonstrated benefits arising from the cross-linking properties such as patterning possibilities and dewetting anihilation. 7 The methacrylic nature of the comonomers constituting the TC material makes it susceptible to depolymerization under UV-stimulus. We were thus able to achieve the TC removal via an "UV+wet" etch (Supporting information and Supporting Figure S1).…”

“…Such materials present balanced affinity for either blocks and therefore provide a thermodynamic driving force to promote perpendicular orientation of the nanodomains. 7,8 We recently demonstrated the perpendicular orientation of lamellar high-χ BCP systems based on poly(1,1-dimethyl silacyclobutane)-block-polystyrene (PDMSB-b-PS), where the topinterface is neutralized using a functional chemically crosslinked top-coat material that enables breakthrough properties, such as patterning, dewetting cancelation and stacking of BCP 2 films. 7 PDMSB-b-PS combines two main advantages for highresolution nanolithography via DSA.…”