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The sidewall roughness of through-silicon vias (TSVs) plays a critical role in the reliability and integrity of signal transmission, particularly at high frequencies. In this study, we introduce a novel approach utilizing generalized closed-form expressions to assess the parasitic RLGC parameters resulting from the sidewall roughness of TSVs under high-frequency conditions. By comparing the calculated results for different sidewall roughness with the outcomes from full-wave electromagnetic (EM) simulations, a high degree of consistency is maintained. Simultaneously, the parasitic parameters showcase systematic variations that correspond to changes in sidewall roughness. Our findings underscore that the adverse impact of TSVs’ parasitic effects becomes more pronounced with heightened sidewall roughness. Importantly, the comparative analysis shows that the correction factor for inductance surpasses that of resistance, underscoring the significance of parasitic inductance. This finding attributes the primary source of parasitic effects to the parasitic inductance resulting from sidewall roughness. In addition, this study meticulously scrutinizes the experimental results, drawing comparisons against both calculated and simulated outcomes, resulting in a good degree of concurrence. This synchronization suggests that the proposed closed-form expressions adeptly capture the nuances of sidewall roughness in TSVs and thus prove highly suitable for scrutinizing a gamut of parasitic effects stemming from sidewall irregularities.

This brief presents a synthesis methodology for miniaturized bandpass filter using an integrated dual composite right/left-handed (ID-CRLH) resonator unit by through glass via (TGV) technology. The mapping between the circuit parameters and the layout structure is proposed to provide an insight into the characteristics of the resonator for the purpose of guiding the design of the filter. TGV plays an irreplaceable role in ID-CRLH as a means of integration. Subsequently, the miniaturization and design flexibility benefits of TGV as an interconnect component, equivalent inductor and coupling element are elaborated. Additionally, the fractional bandwidth tunability from 14% to 34% and the ultra-compact circuit area of $0.067\lambda _{g}\times 0.051\lambda _{g}$ further reveal the superiority of this configuration. Furthermore, two prototypes characterized by broadband and miniaturization are designed and manufactured to unveil the correctness and advancement of this synthesis procedure. The simulated and measured response curves demonstrate the good agreement.

The sidewall roughness of through-glass vias (TGVs) at high frequencies significantly impacts the integrity and reliability of signal transmissions via the inductance and resistance-correction factors resulting from the combined effect of the skin depth and sidewall roughness. Here, to further investigate the generation and mechanism of the correction factors, a hemispherical physical model of the sidewall roughness of actual TGVs is proposed, and the ${RL}$ model comprising the skin depth and sidewall roughness is derived; the measured results were compared with the causal hemispherical model and the multilevel causal Huray model, and it was verified that the proposed hemispherical model can calculate the ${RL}$ parasitic parameters of TGV with high accuracy. Concurrently, the proposed hemispherical model confirms that the correction factor for internal inductance is larger than that for resistance; it can explore the main source of sidewall-roughness-induced parasitic effects. Moreover, the model offers a solution for reducing the sidewall-roughness-induced parasitic effects.

In glass-based 3-D integrated circuits (ICs), nonuniform through-glass vias (TGVs) contribute to increased delay, higher losses, and performance degradation, particularly notable in dense multilayer stacked circuits operating at high frequencies. To explore high-speed, low-loss vertical interconnections, we develop nonuniform TGVs double-layer vertical interconnect models and analyze impedance, insertion loss, and delay across various taper and sidewall roughness configurations. This study confirms a positive correlation among sidewall roughness, taper, and both loss and signal delay. Detailed examination of Smith charts for double-layer vertically interconnected TGVs further illustrates worsening impedance matching with increasing sidewall roughness and taper. In addition, we extract parasitic RLGC parameters, revealing that increased taper exacerbates parasitic effects induced by sidewall roughness, providing evidence for observed losses and delays. Our findings underscore the superior performance of cylindrical TGVs, advocating smaller taper and lower sidewall roughness for enhanced microwave performance in multilayer vertically interconnected devices. Experimental validation supports our conclusions, with measured results aligning well with simulations up to 40 GHz. Moreover, increased multilayer misalignment is confirmed to correlate with higher signal transmission loss and delay, while the loss positively correlates with the radius of pads between interconnection layers.

Chalcogenide phase change materials (PCMs) stand as promising contenders in the realm of radio frequency (RF) switches owing to their remarkable attributes including high switching speed, strong integration potential, and low-power consumption. This study endeavors to explore methods for reducing the resistance of germanium telluride (GeTe) film in its crystalline phase and consequently lowering the RF insertion loss (IL) in a phase change switch. The investigation revealed that oxidation in GeTe thin films induces changes in crystalline resistance. To mitigate oxidation, plasma bombardment with Ar+ was employed, demonstrating a substantial decrease in the resistance of crystalline film. The optimized GeTe-based phase change switch achieved an ideal resistance of $7~\Omega $ for the on-state and 1.2 M $\Omega $ for the off-state, respectively. The ${R}_{\text{off}}$ / ${R}_{\text{on}}$ ratio of the switch could reach $1.7\times 10^{{5}}$ . Furthermore, the optimized switch can handle RF power of +37 dBm in the on-state and self-actuates at 30 dBm in the off-state. RF measurements show that the IL is better than 0.4 dB and the isolation is better than 17 dB from 1 to 20 GHz.

In this article, an implementation method for compact basic passive devices is proposed, in which the vertical interconnects are optimized by the through glass vias (TGVs) technique. The ultrafast laser-induced etching method is used to achieve TGV structure with high aspect ratio, which is the cornerstone for achieving high integration density passive devices. Inductors and capacitors as widely employed passive devices are straightforward and convincing examples to illustrate the application of TGV interconnects. Three-dimensional spiral inductor as a research prototype utilizes high aspect ratio TGV technique to equalize planar and vertical interconnects. On the other hand, the layout is further optimized and discussed by implementing different diameters of TGV on the same glass substrate. From the harvested analysis results, the inductor can achieve the desired inductance density of 198.29 nH/mm2. Subsequently, we first proposed a compact 3-D interdigital capacitor loaded with TGVs array. By further tapping into the vertical space, this configuration takes full advantage of the coupled electric fields between TGVs within the array in addition to the lateral electric fields between adjacent fingers. Additionally, for the purpose of verification, TGV-based 3-D inductors and capacitors have been fabricated and measured. Excellent consistency can be acquired from the extracted inductance and capacitance.

In this letter, a novel slow-wave substrate integrated waveguide (SW-SIW) with low loss and miniaturized dimensions is presented. The SW effect is obtained by incorporating metalized blind vias at the bottom and metalized blind trenches at the top of the single-layer substrate integrated waveguide (SIW). This improved SIW-based topology achieves a dramatic cutoff frequency reduction of 56% with reference to the conventional SIW with the same lateral size. Meanwhile, the proposed topology is realized using laser-induced wet etching (LIWE) through glass vias (TGV) technology. Compared to the printed circuit board (PCB) process, the adopted TGV technology shows the advantages of high precision, high integration, and simplified process. A prototype is fabricated for a proof-of-concept, and the measured results are in good agreement with simulated results indicating the potential of the presented SW-SIW for high-performance millimeter-wave (mm-wave) circuits and systems.

The integrity and reliability of signal transmission in glass 3-D integrated circuits (ICs) can be improved by studying the effect of sidewall roughness of through-glass vias (TGVs) on microwave performance. Thus, in this study, the effect of different sidewall roughness of TGVs on the electrical characteristics, such as loss, delay, and impedance correction factors, are analyzed by extracting S-parameters from the CPW-TGVs-CPW model. An accurate RLGC electrical model of TGVs that considers sidewall roughness is proposed. The correction factor of inductance is verified and found to be greater than that of resistance through simulation, physical measurements, and microscopic characterization analysis. Meanwhile, the sidewall roughness was improved by controlling the laser-induced wet etching (LIWE) process of TGVs. It was greatly reduced from $1.257 \mu \text{m}$ to 25 nm. The proposed electrical model is accurately verified below 40 GHz by extracting the electrical parameters of TGVs with different sidewall roughness.

This article presents a design of Ka -band absorptive filtering packaging antenna (AFPA) based on through-glass vias (TGVs). Compared to other reflective filtering antennas (RFAs), the AFPA showcases a distinct design featuring dual absorptive band-edge radiation nulls and four reflective stopband radiation nulls. Additionally, the AFPA used a glass multilayer stacked 3-D package scheme that enables good microwave characteristics and high-density interconnects. The radiating patch was composed of an RFA and band-stop filter (BSF) whose reflection coefficients were almost complimentary. The RFA radiating patch and BSF unit were comprised of defect microstrip structure (DMS) and defect ground structure (DGS), corresponding dimensions were $\lambda _{g}$ /4 and $\lambda _{g}$ /2, respectively. The radiating patch layer was connected to the substrate-integrated waveguide (SIW) feeding structure layer through a glass transition layer with TGVs and pads, and the packaging process was accomplished using laser bonding. Then we used SIW operating in Ka -band to feed the AFPA. To validate this design, a prototype of the AFPA was fabricated and measured. The results indicate −10 dB impedance bandwidth ranging from 30 to 35 GHz, with a peak gain of 6.06 dBi and a maximum radiation efficiency of approximately 85%. The measurements reveal that the AFPA has dual absorptive band-edge radiation nulls at 30.9 and 33.5 GHz, and four reflective stopband radiation nulls at 25.9, 27.3, 35.1, and 38.4 GHz, with a suppression level exceeding 15.5 dB.

There are many applications for glass-to-glass bonding, such as manufacturing optical devices, electronic components, and microsystem applications. This article presents a simple and effective method for glass-to-glass bonding using laser modification with Ti/Cu/Ti/TiO2 thin films. Ti/Cu/Ti thin films were prepared on glass using magnetron sputtering and then exposed to the atmosphere for 30 min at room temperature for preoxidation to obtain Ti/Cu/Ti/TiO2 thin films. The TiO2 thin film was intentionally formed to improve the bonding quality. To analyze the bonding mechanism, the energy dispersive spectroscopy (EDS) and X-ray photoelectron spectra (XPS) analyses studied the microstructural evolution. The results show that Si diffuses from the glass to the thin films by laser irradiation. The laser beam penetrated the glass and was directly absorbed by the TiO2 thin films. Ti diffuses from the oxide thin film toward the glass, forming Ti–Si covalently structured silicate (the main component is TiSi2) in the bonded region. The formation of TiSi2 is the critical process for this laser bonding. Furthermore, the bonding strengths corresponding to different contact pressures applied during the bonding process were compared and analyzed. The results show that the method achieves more robust glass/TiSi2/Ti/Cu/TiSi2/glass bond pairs with tensile strengths up to 14 MPa and low bonding defect density (< 0.05%). Note that this laser bonding technology was processed at room temperature, allowing the use of thermally sensitive materials in device manufacturing. To verify the application potential of the laser bonding technique in 3-D glass packaging, a simple coplanar waveguide (CPW)–through-glass vias (TGVs)–CPW interconnect structure was developed on three-layer glass interposers in this article. The interconnection loss was successfully measured by constructing a three-layer interconnect structure with laser bonding. The results show that the insertion loss can meet the requirements of glass-based microsystem applications.