Process development in metal/BCB multilayer interconnections of MMCM with embedded chip in Si substrate
A vertical interlayer connection via (VILCV) fabrication process is presented. This process is used for the interconnection of multilayer benzocyclobutene (BCB) based microwave multichip modules (MMCM). The excellent planarity of BCB allows VILCV to be formed using gold electroplating or stud bumps prior to BCB application. And mechanical polishing (MP) planarization is adopted to expose the VILCV, enabling interconnection between different layers. Subsequently upper interconnection is patterned. Metal/BCB multilayer structure can be made by repeating above steps. This approach eliminates the need for laser drilling and plasma etching. Both four terminal Kelvin structures and via chains are fabricated as test vehicles. Finally, a transition of transmission lines in different layers and a packaged MMIC embedded in Si substrate are presented and measured in high frequency range up to 20GHz. The results show there is only minimal performance degradation.
metal/bcb multilayer via microwave multichip module (mmcm) transition