A new thin film innovation has been announced by UltraSource. By eliminating the need for a wirebond, or an air bridge, this consistent, reliable, cost-effective solution called UltraBridge is a useful design option for circuit designers at high frequencies.
In this process, the interconnect conductor layer is applied and patterned right on the substrate surface as an "under" bridge. This is where this technique varies from an air bridge process, which applies the interconnect layer after the thin film conductor layer is complete. Next, silicon nitride (Si3N4) is applied over the interconnect layer to encapsulate it and insulate it from the next metal layer. Then the silicon nitride features are patterned and etched. Contact windows to the interconnect conductor are also made during the pattern and etch of the silicon nitride. Finally, the conventional thin film conductor and resistor layers are applied using standard techniques and processes. The result is a simple, cost-effective method for fabricating high frequency interconnects for Lange Couplers, integrated capacitors and integrated spiral inductors.