Nanostructure engineering by templated self-assembly of block copolymers

Abstract

Self-assembling materials are the building blocks for bottom-up nanofabrication processes, but many self-assembled nanostructures contain defects and lack sufficient long-range order for certain nanotechnology applications. Here we investigate the formation of defects in a self-assembled array of spherical block-copolymer microdomains, using topographical templates to control the local self-assembly. Perfect ordered sphere arrays can form in both constant-width templates and width-modulated templates. For modulated templates, transition between configurations having a constant number of rows and configurations of stable arrays with varying numbers of rows is shown to be analogous to dislocation formation in an epitaxial thin film system. Based on the configuration transition energy and fluctuation energy, designed templates with a high tolerance for lithographical imperfections can direct precisely modulated block-copolymer nanostructures. This study provides insights into the design of hybrid systems combining top-down and bottom-up fabrication.

A Path to Ultranarrow Patterns Using Self-Assembled Lithography

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Templated self-assembly of block copolymer thin films can generate periodic arrays of microdomains within a sparse template, or complex patterns using 1:1 templates [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . However, arbitrary pattern generation directed by sparse templates remains elusive.

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“…Block copolymer thin film self-assembly on an unpatterned substrate leads to close-packed arrays of features such as lines or dots that lack long-range order, thus limiting their utility. As a result, both chemical and topographical substrate features have been used to template or guide block copolymer self-assembly, imposing long-range order and generating microdomain geometries not observed in untemplated films [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . These templates are often defined using electronbeam lithography (EBL) [3][4][5]7,8,11 , because of its ability to pattern small features of arbitrary geometry.…”

“…Most work on the templated self-assembly of block copolymers for nanolithography has focused on the generation of periodic patterns of parallel lines, close-packed dots or concentric rings, using shallow trenches 1,6,9,10,[12][13][14]22,24,26 , sparse post arrays 3 or chemical templates with a periodicity either similar to that of the BCP 2,7,8,15 or a factor two, three or four times larger 3-5 . Nealey and colleagues have shown that non-regular features such as lamellae with bends 2,11 or square-packed dots 15 could be formed using a chemical pattern of the same density as the desired block copolymer pattern.…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…[270][271][272][273] PS-b-PFDMS thin films were assembled under confinement in etched nanochannels with differing widths (30 -80 nm) followed by O2 RIE. 273,274 When the row spacing of the diblock copolymer and the channel width were equal, spheres of PFDMS were formed.…”

Enabling complex nanoscale pattern customization using directed self-assembly

“…The directed self-assembly (DSA) of BCP thin films using chemical [3][4][5][6][7][8] or topographical [9][10][11][12][13][14][15][16] templates to impose long-range order and registration on the BCP domains has garnered increased interest in recent years as a means to enhance lithographic resolution by multiplying the feature density [5][6][7][8][13][14][15] and rectifying pattern non-uniformity or imperfections 5,6,17,18 of lithographically defined templates. Selective removal or alteration of one block then creates a mask that may be combined with other manufacturing techniques to fabricate devices such as patterned magnetic recording media 19 , silicon nanowire transistors 20 or FinFETs 21 .…”