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High-Q copper inductors were fabricated on low-cost and low-loss bismaleimide triazine (BT) and glass substrate using electroplating process. A differential LC voltage-controlled oscillator (VCO) circuit was designed using these high-Q inductors at 2.4 GHz. Flip chip and multichip module (MCM) technologies were applied to assemble the active chips on BT and glass substrate. The inductors exhibited Q-factor as high as 25 at 2.4 GHz. VCOs with copper inductors on BT and glass substrate had phase noise of-108 dBc/Hz at 600 kHz offset for a 2.4-GHz carrier, which is 6-dB improvement compared with the one with on-chip Al inductors. There was almost no substrate loss for inductors on BT and glass substrates. The effect of fabrication defect and solder joint resistance were also investigated. This technique can be extended to other building blocks, thus realizing integration of the whole RF system. [ABSTRACT FROM AUTHOR]

In this paper, we present the detailed fabrication process, high-frequency characterization, and modeling of through-wafer copper-filled vias ranging from 50- to 70-μm-in diameter on 400-μm-thick silicon substrates. The high aspect ratio via-holes were fabricated by carefully optimizing the inductively coupled plasma deep reactive ion etching process. The high aspect ratio via-holes are completely filled with copper using a bottom-up electroplating approach. The fabricated vias were characterized using different resonating structures based on which the inductance and resistance of the filled via-holes are extracted. For a single 70-μm via, the inductance and resistance are measured to be 254 pH and 0.1 Ω, respectively. In addition, the effect of the physical arrangement and distribution in multiple-via configurations on the resulting inductance is also evaluated with double straightly aligned quadruple and diagonally aligned quadruple vias. Physical mechanisms of the dependence was depicted by electromagnetic simulation. An equivalent-circuit model is proposed and model parameters are extracted to provide good agreement. [ABSTRACT FROM AUTHOR]