PMGI Resist Characterisation - Through-Silicon Via Conformal Coat

The limiting factor for the future implementation of 3D ICs is through silicon via (TSV)
technology, which must first be proven so as to enable the necessary layer
interconnections. This project studies the electrical properties of the spin-on dielectric
PMGI in conjunction with MicroChem Corporation, as it is essential that these be
determined before devices containing a large number of TSVs can be implemented on an
industrial scale. Additionally, the spinning process is characterised in relation to different
via fill behaviours, along with PMGI strip rates.


From experiments carried out during this project, it has been found that PMGI exhibits a
relative dielectric constant of ~ 2.5, bulk resistivity of >2.8×10^14 Ohm-m, surface resistivity
of 9.1×10^14 Ohm per sq, low dissipation factor of 0.01 (at 100 kHz), and a high breakdown
voltage of >100 MV/m, making it an excellent candidate for use in TSVs.


With quantifiable reflow properties, and a low strip time in NMP of 40 s at 70 °C,
PMGI is a promising dielectric which would benefit from further characterisation with a
view to implementing vias in industry within the next two to three years.