Hierarchical Self-Assembly of Thickness-Modulated Block Copolymer Thin Films for Controlling Nanodomain Orientations inside Bare Silicon Trenches.

Jin Yong Shin,Simon Kim,Young Taek Oh,Seung Won Seon,Bong Hoon Kim,Shin Park,Hoe Yeon Lim,Seung Soo Mun,Young Chun Ko,Se Gi Lee,Bom Lee

doi:10.3390/polym13040553

Abstract

We study the orientation and ordering of nanodomains of a thickness-modulated lamellar block copolymer (BCP) thin film at each thickness region inside a topological nano/micropattern of bare silicon wafers without chemical pretreatments. With precise control of the thickness gradient of a BCP thin film and the width of a bare silicon trench, we successfully demonstrate (i) perfectly oriented lamellar nanodomains, (ii) pseudocylindrical nanopatterns as periodically aligned defects from the lamellar BCP thin film, and (iii) half-cylindrical nanostructure arrays leveraged by a trench sidewall with the strong preferential wetting of the PMMA block of the BCP. Our strategy is simple, efficient, and has an advantage in fabricating diverse nanopatterns simultaneously compared to conventional BCP lithography utilizing chemical pretreatments, such as a polymer brush or a self-assembled monolayer (SAM). The proposed self-assembly nanopatterning process can be used in energy devices and biodevices requiring various nanopatterns on the same device and as next-generation nanofabrication processes with minimized fabrication steps for low-cost manufacturing techniques.

Highlights

Directed self-assembly (DSA) lithography based on a block copolymer (BCP) can be used to fabricate nanometer-scale patterns on a large scale; it can be applied to various nanomaterials and nanodevices [1,2,3]
We studied the morphology of nanodomains of a BCP thin film with a thickness gradient in the topological nano/micropattern of a bare silicon trench without thickness gradient in the topological nano/micropattern of a bare silicon trench without chemical pretreatments
Our study reveals that the morphology of the BCP nanodomain chemical pretreatments

Summary

Introduction

Directed self-assembly (DSA) lithography based on a block copolymer (BCP) can be used to fabricate nanometer-scale patterns on a large scale; it can be applied to various nanomaterials and nanodevices [1,2,3]. Chemical epitaxy [4,5], graphoepitaxy [6,7,8], electric/magnetic field [9,10], mechanical shear [11], and solvent/laser annealing [12,13] are representative examples in the research field of BCP lithography Among these techniques, graphoepitaxy using topological confinement is a promising next-generation semiconductor device fabrication process [14]. In the graphoepitaxy approach, the primary goal is to perfectly align the surface perpendicular to the BCP nanodomain; realizing both the surface-perpendicular and surface-parallel BCP nanodomains simultaneously on the single substrate is challenging [18,19,20] Fabricating such morphology is possible with control of the local surface energy of the substrate; this requires additional nanopatterning processes such as lithography and dry etching

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Conclusion