Many 3D IC applications such as MEMS and RF systems require Through-Silicon Via(TSV) with operations for high-speed vertical communication.In this paper,we introduce a novel air-gap coaxial TSV that is suiTab.for such RF applications.Firstly,the detailed fabrication process is described to explain how to acquire such a structure.Then,an Resistor Inductance Conductance Capacitance(RLGC) model is developed to profile the transverse electromagnetic field effect of the proposed air-gap TSV.The model is further verified by a 3D field solver program through the S-parameter comparison.With reference to the numerically simulated results,this analytical model delivers a maximum deviation of less than 6‰,on the conditions of varying diameters,outer to inner radius ratios,and SU-8 central angles,etc.Taking advantages of scalability of the model,a number of air-gap-based TSV designs are simulated,providing 1.6~4.0 times higher bandwidth than the conventional coaxial TSVs and leading to an efficient high frequency vertical RF interconnection solution for 3D ICs.
Many 3D IC applications such as MEMS and RF systems require Through-Silicon Via (TSV) with operations for high-speed vertical communication. In this paper, we introduce a novel air-gap coaxial TSV that is suiTab, for such RF applications. Firstly, the detailed fabrication process is described to explain how to acquire such a structure. Then, an Resistor Inductance Conductance Capacitance (RLGC) model is developed to profile the transverse electromagnetic field effect of the proposed air-gap TSV. The model is further verified by a 3D field solver program through the S-parameter comparison. With reference to the numerically simulated results, this analytical model delivers a maximum deviation of less than 6%0, on the conditions of varying diameters, outer to inner radius ratios, and SU-8 central angles, etc. Taking advantages of scalability of the model, a number of air-gap-based TSV designs are simulated, providing 1.6-4.0 times higher bandwidth than the con- ventional coaxial TSVs and leading to an efficient high frequency vertical RF interconnection solution for 3D ICs.