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BCB with nano-filled BaSrTiO3 for thin film capacitors

: Töpper, M.; Fischer, T.; Zoschke, K.; Zang, M.; Teipel, U.; Fehrenbacher, U.; Reichl, H.


Institute of Electrical and Electronics Engineers -IEEE-:
IEEE 59th Electronic Components and Technology Conference, ECTC 2009. Vol.2 : San Diego, CA, USA, 26 - 29 May 2009
New York, NY: IEEE, 2009
ISBN: 978-1-4244-4475-5
ISBN: 978-1-4244-4476-2
Electronic Components and Technology Conference (ECTC) <59, 2009, San Diego/Calif.>
Fraunhofer IZM ()
Fraunhofer ICT ()

A BaSrTiO3-BCB composite was developed for spin-coating to integrate capacitors into multilayer wiring for Wafer Level Packaging (WLP) and System in Package (SiP). The size of nanoscale barium strontium titanate crystallite size was measured as 24 nm. The matrix for the composite was BCB with 63 wt.-% solids dissolved in mesitylene. Various dispersants were tested to find the best surfactant for the stabilization of BaSrTiO3 in mesitylene, which is compatible with BCB. The optimum dispersant was used for preparation of suspensions with a solid loading of 20 35 wt.-% BaSrTiO3 dispersed in mesitylene using 5.0 - 10 wt.-% dispersant. The resulting average layer thickness of the cured composite is in the range of 1.7 mu m. These films can be easily integrated into existing thin film multilayer built-up wiring structures. The relative dielectric constant epsilon(r) of the investigated BaSrTiO3-BCB composite is 31. The breakdown voltage of the exceeds 170 V for 1.7 urn thickness which equals a dielectric strength of 1.0 MV/cm. High reliability was proven for humidity storage (85 degrees C and 85% rel. humidity, 2000 hrs) and thermal cycling from (AATC from 55 degrees C to +125 degrees C, 2000 cycles).