Design review on capacitive coupling interconnect for 3DIC

A capacitive coupling interconnect (CCI) is formed with top metals from two separate dies when they are stacked in face-to-face configuration. The CCI provides inherent advantages of 3D integrations such as high level of communication parallelism and heterogeneity in much larger scale compared to μ-bump technologies because the CCI electrodes can be as small as 8 × 8 μm² compared to approximately 25 × 25 μm² pad dimension of μ-bump. In this paper, various challenges of the CCI from interconnect modeling to circuit design are discussed. The implementation issues such as electrodes alignment and crosstalk among proximity CCIs are also presented with different solutions from several reported designs. Some possible applications of the CCI are discussed and its future trend is examined based on the data reported in literature.