Low-Loss, High-Linearity RF Interposers Enabled by Through Glass Vias

This letter reports on a new low-loss and high-linearity 3-D wafer-level interposer technology enabled by through glass vias (TGVs) with an inverted via configuration. The proposed TGV utilizes a tapered via sidewall profile to achieve a void-free conformal metal coverage with lower process time and fewer fabrication steps than a fully filled conventional TGV. Measurement results for a single 100-μm-tall TGV show an insertion loss of 0.014 dB at 10 GHz and a dc resistance of 28 mQ. Finally, this letter reports, for the first time, on nonlinearity measurements of TGVs. Single-tone measurements show that the third-harmonic level for a coplanar waveguide (CPW) TGV test structure is only 2 dB higher than a reference CPW through line without TGVs, indicating an overall excellent linearity performance.