Enhancd Copper Adhesion on Glass Via Adhesion Promotion Coating

Seed copper metallization on glass has been achieved by simple wet chemistry methods that involve deposition an adhesion promoting organic material which enables metallization without any special or high-temperature treatment of the glass substrate. The coating is catalytically activated by depositing atomic palladium using LMIx®, a Liquid Metal Ink organic precursor of palladium with a low contact angle, in which the “x” subscript denotes formulaic tailoring to specific substrate applications. Catalytic atomic palladium was generated on the organic coating by thermal processing at <230°C or in fact at room temperature by using an appropriate reducing agent. The catalytic layer/s of atomic palladium respond faithfully to commercial electroless copper chemistries furnishing a conductive copper layer. The adhesion of the copper layer was tested using conventional cross-hatch testing and nano-scratch testing methods. AFM was used as a tool to monitor changes in surface roughness during multiple process steps. FESEM/EDX spectra were taken after catalytic palladium and SEM of electroless copper deposition. Also, XPS imaging was used to further understanding the chemical conversion of atomic palladium. DSC/TG runs of the atomic palladium ink formulation in air were used to suggest appropriate thermal processing parameters. Sheet resistance of electroless copper was assessed by the 4-point probe method. Glass substrates with high aspect-ratio Through Glass Vias were subjected to BIB/FIB followed by SEM/EDS analysis to determine coverage and conformality of electroless copper deposition in the vias.