This paper presents the modeling, design, fabrication, and characterization of an innovative and miniaturized thin-film bandpass filter with coupled spiral structures in ultrathin glass substrates (30– $100~\mu \text{m}$ ). This filter is demonstrated for two applications: 3-D integrated passive devices and embedded thinfilm filters in RF modules. A compact filter design was achieved through an integrated resonant structure that effectively utilizes the inductive and capacitive coupling between metal layers on either side of an ultrathin glass substrate or organic build-up layer. The designed filters (layout area $150~\mu \text{m}$ device thickness) were fabricated on a 30- $\mu \text{m}$ -thin glass substrate using a panel-based low-cost approach with double-side thin-film wiring processes. The effect of process variations on the performance of the proposed structures was also studied. Furthermore, an improved WLAN filter is designed and demonstrated by employing specific structural modifications. The measured frequency response of the filters shows good model-to-hardware correlation, with very low insertion loss (0.6 dB) in the passband, and high adjacent-band rejection (>25 dB).

Miniaturized Bandpass Filters as Ultrathin 3-D IPDs and Embedded Thinfilms in 3-D Glass Modules

A novel synthesis method for lumped-element bandpass filters is proposed on the basis of frequency-dependent coupling matrices, which can preserve the moderate bandwidth response matching with coupling matrix prototype better. The available element values of resonators and inverters with the acceptable quality factor are determined by adjusting normalized slope parameters or reference susceptance parameters. To validate the design approach, two third-order inline filters with the fractional bandwidth of 20% at a center frequency of 3 GHz are designed and fabricated in the GaAs HBT technology. Good agreement is obtained between the simulated and measured results. The measured shape factors K20dB of the two filters with and without external couplings are 1.8 and 1.85, respectively. The filter followed by a one-stage amplifier also demonstrates the high frequency selectivity.

Synthesis and Design of Lumped-Element Filters in GaAs Technology Based on Frequency- Dependent Coupling Matrices

This paper demonstrates, for the first time, an integrated trench-based shielding for electromagnetic interference (EMI) isolation between components in an ultra-miniaturized radio frequency (RF) package. A novel component-level shielding structure is explored and developed using metallized trenches formed in the build-up layers of ultra-thin glass substrates. Through full-wave electromagnetic (EM) simulation, the coupling between different passive structures are compared. Additionally, the shielding effectiveness of trench-based structures are compared with traditional via-based shields. Further, the shield effectiveness of different magnetic and non-magnetic shield materials are compared through analytical modeling. Based on these modeling results, a representative shield structure is designed, fabricated and characterized to correlate its performance with simulations. It is observed through measurements, that package-integrated trench-based shields provide up to 25dB more lateral isolation than via-arrays.

Modeling, design and demonstration of integrated electromagnetic shielding for miniaturized RF SOP glass packages

Ultraminiaturized Three-Dimensional IPAC Packages With 100 μm Thick Glass Substrates for Radio Frequency Front-End Modules

This chapter describes ultrathin tantalum-based high volumetric density power capacitors for 1-10 MHz frequency applications with low leakage properties. Dielectrics with low defect density were grown on high surface-area sintered tantalum anodes using selflimiting anodization process. The fundamental mechanisms that govern the film growth and quality are investigated to provide anodization process guidelines. Thiophene-based conducting polymers were used as the cathodes. Complete filling of conducting polymer was achieved by optimization of conducting polymer application process. EDS and structural SEM studies were performed to investigate the morphology and structure of the tantalum pentoxide films. The fabricated capacitor showed 0.1 μF/mm of capacitance density in the 1-10 MHz range, which is 6X enhancement relative to the commercially available power capacitors. The leakage properties of the anodized porous tantalum are investigated with different leakage models used to identify the defect mechanisms in the tantalum pentoxide formed at different voltages.

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Nanoscale electrode and dielectric materials, processes and interfaces to form thin-film tantalum capacitors for high-frequency applications

This paper describes an innovative 3D IPAC (Integrated Passive and Active Components) concept for ultra-miniaturized and highly-functional sub-systems, going beyond discrete passives and Integrated Passive Devices (IPDs). The 3D IPAC concept consists of an ultra-thin 3D structure made of low loss and ultra-thin glass substrates with small-diameter through-vias, and ultra-thin active devices and thin or thick passive films or thin discrete passives on both sides. The first part of the paper describes the benefits of the 3D IPAC concept. The second part of the paper describes a wireless power telemetry module for a bioelectronic system application, and provides proof-of-concept demonstrations for the thinfilm passive components as a building block in the 3D IPAC telemetry module.

Jinxiang Dai

Papers

3D IPAC — A new passives and actives concept for ultra-miniaturized electronic and bioelectronic functional modules