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

• Published in: IEEE microwave and wireless components letters Vol. 28; no. 11; pp. 960 - 962
• Main Authors: Shah, Umer, Liljeholm, Jessica, Campion, James, Ebefors, Thorbjorn, Oberhammer, Joachim
• Format: Journal Article
• Language: English
• Published: IEEE 01.11.2018
• Subjects: Coplanar waveguides; Fabrication; Glass; Heterogeneous Integration; High Linearity; Insertion loss; Low Loss; Micromachining; Silicon; through glass via (TGV); Through-silicon vias
• ISSN: 1531-1309; 1558-1764; 1558-1764
• DOI: 10.1109/LMWC.2018.2869285

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-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-tall TGV show an insertion loss of 0.014 dB at 10 GHz and a dc resistance of 28 <inline-formula> <tex-math notation="LaTeX">\text{m}\Omega </tex-math></inline-formula>. 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.