We review the history and current status of ion exchanged glass waveguide technology. The background of ion exchange in glass and key developments in the first years of research are briefly described. An overview of fabrication, characterization and modeling of waveguides is given and the most important waveguide devices and their applica- tions are discussed. Ion exchanged waveguide technology has served as an available platform for studies of general waveguide properties, in- tegrated optics structures and devices, as well as applications. It is also a commercial fabrication technology for both passive and active wave- guide components. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Ion-exchanged glass waveguide technology: a review

Interconnecting integrated circuits (ICs) and 3-D-ICs to the system board (printed circuit board) are currently achieved using organic or silicon-based interposers. Organic interposers face several challenges in packaging 2-D and 3-D-ICs beyond the 32-nm node, primarily due to their poor dimensional stability and coefficient of thermal expansion (CTE) mismatch to silicon. Silicon interposers made with back-end of line wafer processes can achieve the required wiring and I/O density, but their high-cost limit them to high-performance applications. Glass is proposed as a superior alternative to organic and silicon-based interposers for packaging of future ICs and 3-D-ICs with highest I/Os at lowest cost. This paper presents for the first time a novel thin and large panel glass interposer capable of scaling to 700 mm and larger panels with potential for significant cost reduction over interposers made on 200-mm or 300-mm wafers. The formation of small through vias at high speed has been the biggest technical barrier for the adoption of glass as an interposer and system substrate; and this paper describes pioneering research in via-formation in thin glass substrates, using a novel “polymer-on-glass” approach. Electrical modeling and design of through package vias (TPVs) in glass is discussed in detail, and the feasibility of 50-μm pitch TPVs in 180-μm thin glass substrates has been demonstrated. The excellent surface finish and low CTE of glass leads to increased I/O density, and increased functionality per unit area leading to system miniaturization.

Low-Cost Thin Glass Interposers as a Superior Alternative to Silicon and Organic Interposers for Packaging of 3-D ICs

3D integration consists of 3D IC packaging, 3D IC integration, and 3D Si integration. They are different and in general the TSV (through-silicon via) separates 3D IC packaging from 3D IC/Si integrations since the latter two use TSV but 3D IC packaging does not. TSV (with a new concept that every chip or interposer could have two surfaces with circuits) is the heart of 3D IC/Si integrations and is the focus of this investigation. The origin of 3D integration is presented. Also, the evolution, challenges, and outlook of 3D IC/Si integrations are discussed as well as their road maps are presented. Finally, a few generic, low-cost, and thermal-enhanced 3D IC integration system-in-packages (SiPs) with various passive TSV interposers are proposed.

Evolution, challenge, and outlook of TSV, 3D IC integration and 3d silicon integration

This paper reports on glass frit wafer bonding, which is a universally usable technology for wafer level encapsulation and packaging. After explaining the principle and the process flow of glass frit bonding, experimental results are shown. Glass frit bonding technology enables bonding of surface materials commonly used in MEMS technology. It allows hermetic sealing and a high process yield. Metal lead throughs at the bond interface are possible, because of the planarizing glass interlayer. Examples of surface micromachined sensors demonstrate the potential of glass-frit bonding.

Glass frit bonding : An universal technology for wafer level encapsulation and packaging

Long-range surface plasmon resonance and its sensing applications: A review

Interposers for SiP will become more and more important for advanced electronic systems. But through substrate vias are essential for the 3-D integration. Being a standard for laminate based materials this is much more complex for Si-wafers: High speed etching has to be combined with complex electrical isolation, diffusion barriers and void-free Cu-filling. Without doubt this can be solved in lab-scale but for high production scale cost is a tremendous barrier. Glass wafers with W-plugs have been intensively investigated in this paper. A new acronym has been posted to high-light this technology: TGV for Through Glass Vias. The results of modeling and simulation of TGV at RF/Microwave frequencies showed a very good compromise between wafer thickness, TGV-shape and via diameter for vertical metal plugs with 100 µm diameters in 500 µm thick glass wafer still very stable for thin film wafer processing without costly temporary wafer bonding processes. Therefore the HermeS® from Schott was chosen as the basis for a prototype of a bidirectional 4 × 10 Gbps electro-optical transceiver module. Thin film RDL and bumping of these wafers was possible without any modifications to Si-wafer. First thermal cycles showed very promising results for the reliability of this concept.

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3-D Thin film interposer based on TGV (Through Glass Vias): An alternative to Si-interposer

The novel packaging approach glassPack is introduced as System-in-Package (SiP) technology. Wiring length can be reduced and integration density can be increased by stacking different assembled substrate layers and interconnecting them with one another resulting in 3D-SiP. Glass is an excellent material because of matched coefficient of thermal expansion (CTE) to silicon, high thermal load, dielectricity and high optical transparency over a wide wavelength range. Commercially available thin glass foils can be used as substrate material for electronic and optoelectronic modules. The goal of our ongoing development is making glass based packaging competitive with polymer based (e.g. chip-in-polymer) or silicon based packaging (e.g. silicon-through-via, stacked dies by wire bonding). Our work is focused on conductor trace and through-via realization as well as optical lightwave circuits integration using glass as substrate material. For through-vias in glass, holes were drilled in glass wafers by different laser technologies or etched using photosensitive glass and evaluated. Conductor traces and through-via interconnects were deposited on glass. Also, optical waveguide and fluidic channel integration in glass substrates were investigated. This paper presents the first demonstrator of our glass based packaging technology targeting sensor applications. Two silicon dies, a laser diode, two photodiodes and a fluidic-optical chip were mounted on a glass substrate and interconnected by 3D electrical wiring.

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Thin glass based packaging technologies for optoelectronic modules

https://cyberleninka.org/article/n/900670.pdf

Advances in CO2-Laser Drilling of Glass Substrates

Widespread adoption of electro-optical circuit boards based on embedded glass waveguide technology would enable seamless optical connectivity from external fiber-optic networks to system embedded optical interconnect architectures. In this paper, we report on the fabrication of planar multimode waveguides within thin glass foils based on a two-step thermal ion exchange process. Novel lamination techniques were developed to allow glass waveguide panels to be reliably integrated into a conventional electronic multilayer printed circuit board. In addition, a complete suite of optical connector technologies were developed to enable both direct fiber-to-board and board-to-board connectivity. We present the design, development, and characterization of a fully integrated connection platform, comprising a $281 \times 233$
 mm2 multilayer electro-optical backplane with integrated planar glass waveguides, a pluggable connector system, and five pluggable test cards. Both on-card and externally generated 850 and 1310-nm optical test data were conveyed through the connector and waveguide system and characterised for in-system and system-to-system optical connectivity at data rates up to 32 Gb/s per channel exhibiting bit error rates of less than $10^{-12}$
 .

Pluggable Electro-Optical Circuit Board Interconnect Based on Embedded Graded-Index Planar Glass Waveguides

We introduce thin glass for electrical-optical integration on module level. Glass is regarded as promising material for high frequency wiring to drive the e/o components having additional advantages in terms of transparency, waveguide and lens integration capability and PCB integration. Modeling results of vertical and horizontal electrical interconnects show the suitability for certain configurations. The integration schemes will be discussed and experimental results from thin film deposition, laser drilling of through vias and ion exchange for optical waveguides will be presented.

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Lars Brusberg

Papers

3-D Thin film interposer based on TGV (Through Glass Vias): An alternative to Si-interposer

Thin glass based packaging technologies for optoelectronic modules

Advances in CO2-Laser Drilling of Glass Substrates

Pluggable Electro-Optical Circuit Board Interconnect Based on Embedded Graded-Index Planar Glass Waveguides

glassPack — A 3D glass based interposer concept for SiP with integrated optical interconnects