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Sub 15-nm Patterns for Magnetic Recording Using Block Copolymers

What Is The Scientific Achievement?

Cross-sectional SEM image

(a) Cross-sectional SEM image of self-assembled pattern after its transfer to a silicon substrate; (b) Top–down; and (c) cross-sectional SEM images of electron-beam directed assembly of a line-space pattern with 12 nm features, with pattern transfer to a silicon substrate.

Self-assembled block copolymer patterns can be made more resilient to plasma etch processing using the infiltration of metal oxides into the polymer blocks.  This enhancement provides new opportunities for improved high contrast, high fidelity pattern transfer in wafer-scale, sub-15nm electron beam lithography.  However, block selective infiltration alters the feature size, duty cycle, and sidewall profile of the block copolymer pattern.  We have systematically investigated the effects of aluminum oxide infiltration on 27 and 41 nm pitch line/space patterns formed using polystyrene-b-poly(methyl methacrylate) block copolymers and evaluated the compatibility of the process with directed self-assembly.  The degree of image distortion depends on the amount of infiltrated material.  Smaller amounts result in complete mask hardening, while larger amounts shift and collapse the pattern features.  The low line edge roughness (3σ ~ 2.9 nm) and the sufficiently vertical sidewall etch profile of these transferred patterns meets the requirements for technology applications, like bit-patterned magnetic recording media.

Why Does This Matter?

This result meets the specifications for bit-patterned-media magnetic recording systems with densities larger than 1 Tb / in2, which require extremely tight bit placement accuracy and narrow size distribution to achieve synchronization between the recording head and the patterned media.  

What Are the Specifics?

Aluminum oxide mask created through infiltration of block copolymer pattern by trimethyl aluminum vapor and exposure to water vapor, followed by oxygen plasma etching to remove organic material.

CFN Capabilities: Technical expertise in block-copolymer self-assembly; atomic layer deposition tool for block-selective infiltration of aluminum oxide; transmission electron microscopy with elemental mapping to locate the infiltrated material.


R. Ruiz,1 L. Wan, 1 J. Lille, 1 K. C. Patel, 1 E. Dobisz, 1 D. E. Johnston, 2 K. Kisslinger, 2 and C. T. Black, 2

1. HGST a Western Digital Company, San Jose Research Center, San Jose, CA, 95135, USA.
2. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.

Journal of Vacuum Science and Technology B 30, 06F202 (2012).

Acknowledgment of Support

Research was carried out in part at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

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