Incorporation of BCB into Wafer-Scale Assembly MMIC's

Northrop Grumman Aerospace Systems (NGAS) has developed a Wafer Scale Assembly (WSA) process that is compatible with Benzocyclobutene (BCB) processes. BCB is a common dielectric material used to construct multi-metal interconnects. BCB processes enable additional metallization layers to be available for circuits and signal routing. WSA is a technology that physically bonds two or more wafers together to create a hermetically packaged MMIC (Monolithic Microwave Integrated Circuit). Two additional BCB layers, translates to two additional metallizations added to each side of the WSA, increasing the number of interconnect layers on both sides. Combining BCB and WSA processes has several benefits, including but not limited to: added MIMIC design flexibility, MMIC size reduction, and ability to create three-dimensional passive structures. In this paper, results from NGAS' development on the WSA-BCB integration are presented, and key process considerations are discussed.