Electromagnetic modeling and simulation of TSVs in 2.5D interposers for RFICs

This paper presents an approach to RFIC system integration using 2.5D silicon interposers with TSVs which act as an interface between the baseband and RF dies, and also provides adequate isolation reducing EMI. To evaluate the performance of 2.5D integration in RFICs, it is highly essential to study the EMI tolerance behavior of TSVs through accurate models. Current empirical and analytical models of TSVs do not consider the MOS structure, substrate doping, biasing and coupling effects, process-related effects like via tapering and scalloping, and lossy dielectric. This requires a need for an electromagnetic model of TSV considering these various effects to accurately evaluate its performance to aid the design of critical nets for 2.5D integration. We have developed an analytical model for the TSV considering the MOS structure and process-related effects, and verified its performance by comparing it with an electromagnetic model built using the 3D EM full wave solver on Ansys HFSS software platform. Our simulation results shows that the analytical model can be used as a first cut design approximation, while further EM simulations needs to be performed for critical nets to improve shielding from electromagnetic interference (EMI) and crosstalk.