Nanotechnology and Model Catalysis: The Use of Photolithography for Creating Active Surfaces

New and very stable model catalysts have been developed. Two types of samples on oxidized 4-inch wafers were produced using processes that are generally employed in semiconductor device technology. A single wafer exhibits 109 to 1010 active sites on an otherwise flat silicon oxide surface. Sputter etching of a number of bilayers (Pd/SiO2), stacked on an oxidized Si wafer surface resulted in billions of isolated towers, consisting of disks of active metal layers, separated by inert substrate material. A second system was produced by etching pits into a heavily oxidized 4-inch Si wafer. Active material was deposited into the pits by e-beam evaporation or spin-coating of precursor solutions. The topography and chemical composition, and the changes induced by the reaction conditions applied, including stability and chemical behavior of the nanostructured systems, were investigated by means of AFM, SEM, temperature-programmed methods and XPS

Disposable Polymeric Micro-Cantilever Arrays for Sensing

AbstractTo fabricate low-cost polymeric cantilever arrays, we have applied injection molding. For polymers, including polypropylene and polyvinylidenfluoride, cantilever dimensions in the micrometer range with an aspect ratio as large as 10 were successfully manufactured. The cantilevers show a performance similar to the established silicon cantilevers. Combined with functionalization, the cantilever arrays show a great potential in biomedical applications

Optimized staircase profiles for diffractive optical devices made from absorbing materials

We report on the optimization of staircase grating profiles for the case of absorbing grating materials. Using a simple numerical algorithm, we determined the grating parameters, maximizing the first-order diffraction efficiency for different numbers of staircase steps. The results show that there is a significant difference between the staircase profiles for nonnegligible and negligible absorption. The obtained solutions are of importance for diffractive optics in the soft-x-ray and extreme-ultraviolet ranges

Beyond EUV lithography: A comparative study of efficient photoresists' performance

Extreme ultraviolet (EUV) lithography at 13.5 nm is the main candidate for patterning integrated circuits and reaching sub-10-nm resolution within the next decade. Should photon-based lithography still be used for patterning smaller feature sizes, beyond EUV (BEUV) lithography at 6.x nm wavelength is an option that could potentially meet the rigid demands of the semiconductor industry. We demonstrate simultaneous characterization of the resolution, line-edge roughness, and sensitivity of distinct photoresists at BEUV and compare their properties when exposed to EUV under the same conditions. By using interference lithography at these wavelengths, we show the possibility for patterning beyond 22 nm resolution and characterize the impact of using higher energy photons on the line-edge roughness and exposure latitude. We observe high sensitivity of the photoresist performance on its chemical content and compare their overall performance using the Z-parameter criterion. Interestingly, inorganic photoresists have much better performance at BEUV, while organic chemically-amplified photoresists would need serious adaptations for being used at such wavelength. Our results have immediate implications for deeper understanding of the radiation chemistry of novel photoresists at the EUV and soft X-ray spectra.ISSN:2045-232

Efficient Replication of Nanostructured Surfaces

The defined fabrication of nanostructures on surfaces for the nanosciences today largely relies on tools such as scanning probe instruments or electron- and ion beam systems that are serial writing processes. For future production of components and devices, in particular if large nanostructured areas are needed, parallel processes, which are fast and cost-effective, have to be developed. In this paper we review the possibilities for the replication of nanostructures on surfaces using moulding of thermoplastic polymer materials. Using hot embossing, it has been shown that structures below 10 nm can be reproduced reliably and with a high fidelity using laboratory equipment. Mass fabrication of nanostructured components can be achieved using thermal injection moulding with cycle times in the order of 10 sec

Nanoimprint lithography process chains for the fabrication of micro- and nanodevices

The nanoimprint lithography (NIL) process with its key elements molding and thin film pattern transfer refers to the established process chain of resist-based patterning of hard substrates. Typical processes for mass fabrication are either wafer-scale imprint or continuous roll-to-roll processes. In contrast to this, similar process chains were established for polymeric microelements fabricated by injection molding, particularly when surface topographies need to be integrated into monolithic polymer elements. NIL needs to be embedded into the frame- work of general replication technologies, with sizes ranging from nanoscopic details to macroscopic entities. This contribution presents elements of a generalized replication process chain involving NIL and demonstrates its wide application by presenting nontypical NIL products, such as an injection-molded microcantilever. Additionally, a hybrid approach combining NIL and injection molding in a single tool is presented. Its aim is to introduce a toolbox approach for nanoreplication into NIL-based processing and to facilitate the choice of suitable processes for micro- and nanodevices. By proposing a standardized process flow as described in the NaPANIL library of processes, the use of establish process sequences for new applications is facilitated

Analysis of Thin Thermal Oxides on (0001) SiC Epitaxial Layers

In this study, electrical properties of MOS capacitors with varying oxide thicknesses have been investigated. The oxide growth was performed at 1050 °C without any further post-oxidation annealing steps resulting in oxide thicknesses between 2 nm and 32 nm. Capacitance-Voltage measurements revealed a decreasing density of interface defects for increasing oxide thickness suggesting a deterioration of the interface at the initial stage of the growth.ISSN:0255-5476ISSN:1662-975