Partners and International Organizations
(English)
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Fraunhofer-Institut für Silicatforschung, LM Ericsson, Industrial Microelectronics Center, Technische Universität Berlin, BULL S.A., Robert Bosch GmbH, Dassault Electroniques S.A., W.C.Heraeus GmbH, Motorola Ltd. Semiconductor Products, Karl Süss GmbH, Fraunhofer-Institut für Angewandte Optik und Feinmechanik, Chalmers University of Technology, Friedrich-Schiller-Universität, Viasystems
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Abstract
(English)
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For the replication of micro-optical devices UV-curable SolGel materials, such as the ORMOCER®s developed in DONDODEM, offer new properties, which are strongly demanded by commercial applications. Long-term reliability, chemical stability, temperature resistance and good adhesion to the substrate are some of these properties.
Within DONDODEM the tasks of CSEM concerned mainly process and technology development for replication of micro-optical elements into different ORMOCER® materials, technology for laser-fibre coupling and general aspects for applications and technologies in the replication process of ORMOCER®s.
During the last year of the project DONDODEM the processing of various types of ORMOCER®s has been optimised. Pre-treatment of the replication material and the substrate, exposure intensity and thermal curing conditions have a crucial influence on the stability of the fabricated devices. The replicated test samples stand environmental testing according to industrial standards ISO 9022 , IPC TM 650 or Bellcore. The replicated test structures had very different designs. Fine structures with minimum feature sizes of less than 200 nm in lateral extension and only a few nm depth, like antireflection gratings, were replicated, as well as comparatively coarse structures with up to 120 mm depth and a few hundreds of mm lateral extension, which served as mechanical mounting and alignment structures for micro-lenses or optical fibres.
One of these alignment structures has been used to achieve high efficient butt coupling of light from a VCSEL into a multimode fibre (50 mm). The passive alignment structure was replicated directly onto the VCSEL chip. The coupling could then be performed without time consuming active alignment of the fibre in respect to the light source.
A second approach to accomplish laser to fibre coupling has been investigated by using a replicated lens. The system design parameters were modelled using scalar diffraction models in primarily in-house developed custom design tools. Main parameters to be considered are, e.g. the distances VCSEL-lens-fibre, focal length, aperture transmission, diffraction order of the lens, spot size and divergence. Typical laser characteristics have to be taken into account as well as fabrication related limitations. Coupling efficiencies of more than 80% could be demonstrated.
A new generation of complex, replicated structures can be accomplished by combination of lithographic structuring with UV-embossing techniques. Investigations on the required tooling of such a technique led to the construction of a modified mask aligner with additional features for embossing. The modifications concern the mounting stages for the replication mould and substrates, the software for the control of z-axis speed, wedge error compensation and a mechanism to separate the mould from the replica. With this new machine the integration of replication technology and lithography will allow wafer scale replication onto pre-structured substrates and double sided replication, which both will lead to new, complex micro-optical systems.
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