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Peroz C.,Abeam TechNologies, Inc. | Dhuey S.,Lawrence Berkeley National Laboratory | Volger M.,Micro Resist Technology GmbH | Wu Y.,Oxford Instruments | And 2 more authors.

A step and repeat UV nanoimprint lithography process on pre-spin coated resist film is demonstrated for patterning a large area with features sizes down to sub-15 nm. The high fidelity between the template and imprinted structures is verified with a difference in their line edge roughness of less than 0.5 nm (3s deviation value). The imprinted pattern's residual layer is well controlled to allow direct pattern transfer from the resist into functional materials with very high resolution. The process is suitable for fabricating numerous nanodevices. © 2010 IOP Publishing Ltd. Source

Kirchner R.,Paul Scherrer Institute | Schleunitz A.,Micro Resist Technology GmbH | Schift H.,Paul Scherrer Institute
Journal of Micromechanics and Microengineering

An intensive, energy-based analysis of the thermal reflow of thermoplastic polymer structures is presented. Poly (methyl methacrylate) (PMMA) was patterned by grayscale electron beam lithography. The obtained rectangular, micron-scale structures were transformed into lens-like structures by thermal reflow near the glass transition temperature of the original PMMA. Representative parameters obtained from these reflow experiments were used to model the reflow process by using a new, energy-based, finite element, soapfilm method using the free software Surface Evolver. The time-, temperature- and molecular-weight-dependent geometry evolution of the PMMA structures could be described by an apparent contact-angle-evolution time constant and a shape-evolution time constant. The developed model allows the prediction of intermediate geometries during the reflow process occurring between the initial and the final energy optimal geometry. The proposed model is independent from the explicit knowledge of material-specific parameters such as viscosity or glass transition temperature. Extensive experimental data for PMMA reflow is provided. Simulation examples are given for a contact-angle-dominated reflow which demonstrate a good agreement between model and experiment. © 2014 IOP Publishing Ltd. Source

Kirchner R.,TU Dresden | Kirchner R.,Fraunhofer Institute for Photonic Microsystems | Kirchner R.,Paul Scherrer Institute | Finn A.,TU Dresden | And 5 more authors.
Journal of Lightwave Technology

The direct patterning of hybrid-polymer microring resonators with minimal residual layers by UV-assisted nanoimprint lithography is reported. The proposed stamp-and-repeat technology requires no post-processing. The imprint polymer was applied by spin-coating as a 130-150 nm thin initial film for an optimized processing. The importance of the initial film thickness is discussed in detail. Aspect ratios of more than 5:1 were realized with 2 μm high ridge-waveguides and sub-400 nm coupling gaps on maximal 130 nm thin residual layers. The achieved ratio of structure height to residual layer thickness of 15.4 (2 μm versus 130 nm) was much larger than the typical values in high-resolution imprinting and superseded the removal of the residual layer completely. The resonators are thought as biosensor transducers. High quality devices with Q-factors up to 13 000 were produced with a minimal set of process steps. © 2014 IEEE. Source

Schleunitz A.,Paul Scherrer Institute | Spreu C.,Paul Scherrer Institute | Vogler M.,Micro Resist Technology GmbH | Atasoy H.,Micro Resist Technology GmbH | Schift H.,Paul Scherrer Institute
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics

Sloped and stepped 3D structures were added to surface-patterned resists using grey-scale electron beam lithography and thermal reflow. A poly(methyl methacrylate) resist with moderate initial molecular weight of 120 kg/mol was chosen, which enabled processing with both nanoimprint and electron beam lithography. Using proper exposure doses, a molecular weight distribution was generated that allowed a selective thermal postprocessing of the exposed steps while the imprinted gratings on top of the resist were preserved. This allows fabricating mixed structures of microprisms surrounded by large-area nanogratings in the same resist layer. Working stamps were casted from the template pattern and subsequently replicated using thermal nanoimprint. As a possible application, backlight devices with arrays of light outcoupling prisms can be seen. © 2011 American Vacuum Society. Source

Cadarso V.J.,Ecole Polytechnique Federale de Lausanne | Perera-Nunez J.,University of Extremadura | Perera-Nunez J.,CIBER ISCIII | Jacot-Descombes L.,Ecole Polytechnique Federale de Lausanne | And 6 more authors.
Optics Express

Ink-jet printing of optical ink over SU-8 pillars is here proposed as a technology for obtaining microlenses with shape control. To demonstrate the flexibility of this method, microlenses with five different contour shapes (ranging from circular and elliptical to toric or more advanced geometries) have been fabricated. Furthermore, the optical properties of the different fabricated lenses have been experimentally investigated. Focal distance, numerical aperture (NA) and full-width at half maximum (FWHM) of the microlenses have been determined. Arrays of microlenses showed an identical behavior with a standard deviation in the total intensity of only 7%. Additionally, the focal plane of the fabricated symmetric microlenses and the Sturm interval of the non-symmetric ones have been obtained. The experimental results demonstrate the validity and flexibility of the proposed technology. © 2011 Optical Society of America. Source

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