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Coating techniques for 3D-packaging applications

: Töpper, M.; Wilke, M.; Röder, J.; Fischer, T.; Lopper, C.


Institute of Electrical and Electronics Engineers -IEEE-:
IEEE 62nd Electronic Components and Technology Conference, ECTC 2012 : May 29 2012-June 1 2012, San Diego, CA
New York, NY: IEEE, 2012
ISBN: 978-1-4673-1966-9 (Print)
ISBN: 978-1-4673-1964-5 (Online)
Electronic Components and Technology Conference (ECTC) <62, 2012, San Diego/Calif.>
Fraunhofer IZM ()

Spin-on is the method of choice for the deposition of thin film polymers and photo-resists for standard WLP-processes like wafer bumping and redistribution. Topography and deep via holes are the challenges for the 3-D packaging technologies. For examples the depth and the diameter of TSV (through silicon via) and Si-trenches can be in a range of multiple 10-mu ms being far away for spin-on processes which are needed for lithography of wiring systems and side wall passivation processes. A comparison of different coating techniques has been compared in this paper: For spray-coating the polymer precursors have to be modified by dilution with appropriate solvents. Guidance for the selection of solvents for different material combinations will be discussed. A new technology called diffusion coating by the authors has been introduced in this paper. The process is based on a modified spin-on technique. Highly conformal coatings can be achieved for a wide range of materials. Patents are pending. Electrophoretic coating is a special deposition process using electroplating. Dry-film photo-resist by lamination is the process of choice if only the surface of the wafer has to be structured. The main advantage is that no liquid-based resists may flow into TSV or other cavities.