www.afm-journal.de FULL PAPER www.MaterialsViews.com 1102 wileyonlinelibrary.com © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1102 wileyonlinelibrary.com Adv. Funct. Mater. 2011, 21, 1102–1112 Sivashankar Krishnamoorthy,* Krishna Kumar Manipaddy, and Fung Ling Yap 1. Introduction The need for higher performance and miniaturization of devices has raised considerable demand for small scale structures, pushing feature size and spatial resolutions down to sub-50 nm length scales. Such patterns are of high interest for applications in photovoltaics, [1] plasmonics, [2] solid-state lighting, [3] sensors, [4] energy storage, [5] molecular separation, [6] and patterned media. [7] Lithography is a promising means of creating such structures with well-defined feature size, periodicity, and with different combinations of technologically relevant materials and sub- strates. Nanoscale templates for lithography down to sub-50 nm pattern resolutions can be produced using state of the art techniques [8–10] such as e-beam lithography, nanosten- cils, [11,12] X-ray interference, and double exposure patterning with deep UV radiation. However, these techniques encounter the chal- lenges of a) high fabrication costs, b) low throughput, and c) templates lacking durability when the size and periodicity is scaled down. Alternative approaches that allow parallel fabrication of robust, high-resolution lithographic templates over full wafer level are essential for building viable technologies for adop- tion by industry. Pattern integrity across wafer level is crucial to ensure that the devices fabricated across different parts of the wafer exhibit the same characteristics. Microphase separation of block copoly- mers [13–15] in thin films has been widely investigated for nanolithography appli- cations, [16,17] and the ability to vary size, periodicity, and morphology have been convincingly demonstrated. [18,19] How- ever, the process is multi-step and involves time-consuming steps such as surface neu- tralization and annealing of polymer films, each of which can cost several hours. Fur- thermore, when a large number of steps is involved, each processing step can introduce a certain level of non-uniformity. This also makes it difficult to ensure pattern integrity across whole areas of full wafers. [20] A much simpli- fied and direct approach, especially for achieving 2D dot array patterns, is the use of spherical reverse micelles of amphiphilic copolymers. [21,22] Spherical reverse micelles are soft polymeric nanoparticles that can be deposited on a surface and used as- such for lithography. The possibility of using reverse micelles in nanolithography has been presented in earlier reports. [23–25] These papers, however, do not address key limitations that prevent the use of this approach for nanolithography when the features on the template have a thickness or separation approaching sub-10 nm scale. The latter situation is invari- ably encountered, however, when ultrahigh feature and spatial resolutions are sought. Furthermore, the earlier work does not address the unique challenges of achieving uniform patterns of reverse micelles, particularly when coated over large areas such as full wafers. Since annealing above the glass transition temperature of the copolymer destroys reverse micelle-based patterns, the uniformity must be achieved as-coated without additional processing. In this report, we overcome these chal- lenges and convincingly demonstrate Wafer-Level Self-Organized Copolymer Templates for Nanolithography with Sub-50 nm Feature and Spatial Resolutions Robust lithographic templates, with sub-50 nm feature and spatial resolu- tions, that exhibit high patterning integrity across a full-wafer are demon- strated using self-organized copolymer reverse micelles on 100 mm Si wafers. A variation of less than 5% in the feature size and periodicity of polymeric templates across the entire wafer is achieved simply by controlling the spin- coating process. Lithographic pattern transfer using these templates yields Si nanopillar arrays spanning the entire wafer surface and exhibiting high uniformity inherited from the original templates. The variation in geometric characteristics of the pillar arrays across the full-wafer surface is validated to be less than 5% using reflectance spectroscopy. The physical basis of the change in reflectance with respect to sub-10 nm variations in geometric parameters of pillar arrays is shown by theoretical modelling and simulations. Successful fabrication of highly durable TiO 2 masks for nanolithography with sub-50 nm feature width and spatial resolutions is achieved through highly controlled vapour phase processing of reverse micelle templates. This allows lithographic pattern-transfer of organic templates with a feature thickness and separation of less than 10 nm, which is otherwise not possible through other approaches reported in literature. DOI: 10.1002/adfm.201002380 Dr. S. Krishnamoorthy, Dr. K. K. Manipaddy, Dr. F. L. Yap Institute of Materials Research and Engineering (IMRE) Agency for Science Technology and Research (A ∗STAR) 3 Research Link, 117602, Singapore E-mail: krishnamoorthys@imre.a-star.edu.sg