Block Copolymer Nanostructured Thin Films for Advanced Patterning

Block Copolymer Nanostructured Thin Films for Advanced Patterning 

Michelle A. Chavis, Evan L. Schwartz and Christopher K. Ober 

Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853 

One idea to create nanostructured device layers is to use the natural processes of self-assembly to position organic and inorganic molecules from the bottom-up (Feynman, 1959). One particular approach that has received a considerable amount of attention is the use of block copolymers as a patterning material because of their inherent ability to form periodic nanostructures in the mesoscopic (10-50 nm) length scale, coupled to the facility of one of the polymers to be selectively degraded to create nanoporous thin films. These nanoporous films could act like a stencil mask for subsequent etching steps into the underlying substrate. This topic has attracted much attention and inspired several excellent reviews (Fasolka and 

Complex Macromolecular Architectures Synthesis, Characterization, and Self-Assembly, First Edition. 

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Thin films of block copolymers are likely to find many applications as nanostructured materials, due to the ability to tailor nanoscale dot and stripe patterns. Theory for microphase separation in thin films, especially the effect of confinement on structure orientation is now quite advanced. " Models for the effect of confinement on thermodynamics have also been developed, although this aspect has attracted less attention. 

Directed self-assembly shows promise in advanced lithography and a variety of other applications that have less complex requirements. For example, directed self-assembly could be used for enhancing etch selectivity, placing dopants in ordered arrays, or generating high-density, close-packed electrodes in capacitor arrays [6]. Additionally, the assembled nanostructures could be used for fabricating densely packed porous templates [12-14] or membranes [15, 16] at the nanoscale. Other potential applications of assembled block copolymer thin films include the fabrication of MOSFETs (metal-oxide-semiconductor field-effect transistors) [17], quantum dots [18], high surface area devices [19, 20], photovoltaic devices [21], and bit patterned media [22-24]. 

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