Ultra-Compact, High-Performance, 3D-IPD Integrated Using Conformal 3D Interconnects

A 3D technology for fabrication of ultra-compact, high-performance 3D integrated passive devices (3D-IPD) is presented here. The technology comprises high-Q thin film MIM capacitors and high-Q 3D inductors/transformers fabricated on glass substrate using conformal 3D interconnects. MIM capacitors with a capacitance density of 310 pF/mm² are fabricated using low temperature Si3N4 insulator. 3D solenoid inductors/transformers are fabricated using two 15µm thick copper layers, with the second one being 3D and conformal. 3D inductor's/transformer's shape and copper thickness are optimized to increase inductance density, reduce RF losses and enable high power handling. 3D-Components for WLAN applications, such as filters and baluns, have been synthesized, simulated and fabricated using 3D-IPD technology. These devices exhibit low loss and occupy a surface smaller than 1 mm². For example, a 2.4 GHz band-pass filter exhibits -1.7 dB insertion loss and occupies 0.64 mm², whereas, a 5 GHz one exhibits -1.45 dB insertion loss and occupies 0.5 mm². Simulation and measurement results of these devices are presented and discussed in detail in this paper. This new technology will enable integration of ultra-compact, high performance 3D-IPD and will lead to smaller system packages, such as RF-MCM and RF-SiP.