Silicon Bridge Research Articles

Multiring-induced multicolour emission: hyperbranched polysiloxane with silicon bridge for data encryption

The presented work shows an impressive multicolour luminescence hyperbranched polysiloxane attributed to the multiring through-space conjugation named “multiring induced multicolor emission” (MIE), as well as its application in data encryption.

Characterization of 3-D-Mesa Silicon Single Strip Detectors for Use in Synchrotron Microbeam Radiation Therapy

The Centre for Medical Radiation Physics (CMRP) has designed and produced novel n-type silicon single strip detectors (SSDs) for use in dosimetry of synchrotron-based microbeam radiation therapy (MRT). In order to address the challenges of dosimetry and quality assurance of these beams, a detector is required with micron-scale spatial resolution, real-time read-out, large dynamic range, and significant radiation hardness. The CMRP first-generation 3-D-Mesa SSD is fabricated in n-SOI technology and involves plasma etching to produce a 10 $\times $ 36 $\times $ 250 $\mu \text{m}^{3}$ sensitive volume (SV) or a 10 $\times $ 22.5 $\times $ 250 ${\mu }\text{m}^{3}$ SV with all surrounding silicon above the insulating layer removed. The 3-D-Mesa has undergone full electrical characterization and a charge collection study, supported by TCAD simulations to model electric field in the device. The optimal operating bias was found to be −2 V, which produces a dark current of less than 1 nA and 100% charge collection efficiency within the SV. Charge collection is observed at greater biases from the silicon bridge under the Al bus that electrically connects the SV of the SSD to the readout pad. The reasons for this are discussed and will be addressed in the next generation of the 3-D-Mesa SSD.

Embedded Multidie Interconnect Bridge—A Localized, High-Density Multichip Packaging Interconnect

This article provides an overview of the embedded multidie interconnect bridge (EMIB) multichip packaging (MCP) technology. EMIB is a unique packaging paradigm that provides very high-density interconnects (currently in the range of 500–1000 I/O/mm) localized in between two devices, thus enabling high-bandwidth (BW) on-package links while leaving the rest of the package structures and designs unaffected. The construction of the silicon bridge and the package to allow high BW electrical signaling between two dies is discussed in detail. Examples of the EMIB implementations for the links between the field-programmable gate array (FPGA) logic and high bandwidth memory generation 2 (HBM2) memory stacks, graphics die and HBM2 memory stacks, FPGA logic die, and high-performance transceiver die are described. EMIB packaging is compared with similar high-density interconnect technologies such as silicon interposer with through-silicon vias (TSVs) and other fan-out-based package technologies. Design optimization strategies for power delivery and I/O routing in the presence of an embedded bridge are highlighted.

Ultrafast Terahertz Frequency and Phase Tuning by All‐Optical Molecularization of Metasurfaces

AbstractThe integration of photoactive semiconductors exhibiting strong light–matter interactions into functional unit meta‐atoms facilitates effective approaches to dynamically manipulate terahertz (THz) waves. Here, a new metaphotonic modulator is proposed and comprehensively studied, which demonstrates extensive tunability of the resonant frequency and phase with the merit of ultrafast photoswitching. Specifically, parallel silicon (Si) bridges are embedded in metasurfaces to reinforce the connection ability, achieving ultrafast optical molecularization from a magnetic quadrupole into an electric dipole. Under femtosecond pulse excitation, the demonstrated resonant frequency tuning range is as high as 40% (from 1.16 to 0.7 THz) and can be further promoted up to 48% (from 1.56 to 0.81 THz) by varying the Si bridge length. Meanwhile, the phase delay at given frequencies can be controlled up to 53.3° without significantly changing the high transmission. Furthermore, the transient frequency switching and phase shifting dynamics are systematically investigated for the first time, showing a full recovery time within 2 ns. By optically molecularizing metasurfaces, extended tuning ranges with regard to the resonant frequency and phase, as well as an ultrafast switching speed, are simultaneously acquired in the proposed metamodulator, which provides deeper insight into the multifunctional active‐tuning systems.

Design and Demonstration of Glass Panel Embedding for 3D System Packages for Heterogeneous Integration Applications

Abstract This article demonstrates a next-generation high-performance 3D packaging technology with smaller form factor, excellent electrical performance, and reliability for heterogeneous integration. High-density logic-memory integration, today, is built predominantly using interposers which are fundamentally limited in assembly pitch and interconnect lengths, and they also are expensive as the package sizes increase. On the other hand, high-frequency applications continue to use laminates which are also limited by package size and ability to integrate many components. Wafer-level fan-out (WLFO) packaging promises better performance and form factor at lower costs, but current WLFO packages are mold-based and hence are limited to small packages. This article presents a 3D packaging technology using glass panel embedding (GPE) for high-performance with potential for large body size heterogeneous integration applications. The tailorable coefficient of thermal expansion of glass allows a reliable direct board attach of large GPE packages that not only benefits the form factor and signal speed but also provides radical benefits to power delivery. Unlike interposers and silicon bridges, GPE packages are not bump-limited and can support I/O densities comparable with backend-of-line with silicon-like redistribution wiring at much lower costs. The fundamental limitations such as die shift and poor dimensional stability of current organic WLFO packages are addressed by parametric process improvements to reduce die shift to <2 μm while also improving the RDL surface planarity for high-yielding fine-line structures and integrating through glass via (TGV) in the fan-out region for 3D packaging. This article describes the fabrication process for 3D GPE, leading to demonstration of a technology using embedding of chips with all-Cu interconnections at 40-μm I/O pitch with TGVs at 300-μm pitch, thus enabling double-side RDL and assembly of chips to achieve three levels of device integration.

Design and demonstration of Glass Panel Embedding for 3D System Packages for heterogeneous integration applications

Abstract This paper demonstrates a next generation high-performance 3D packaging architecture with smaller form factor, excellent electrical performance and reliability for heterogeneous integration. High density Logic-HBM integration, today, is built predominantly using interposers which are fundamentally limited in assembly pitch and interconnect lengths, and they also are expensive as the package sizes increase. On the other hand, high-frequency applications continue to use laminates which are again limited by package size and ability to integrate many components. WLFO promises better performance and form factor at lower costs, but current WLFO packages are mold-based and hence are limited to small packages. This paper presents the first demonstration of 3D Glass Panel Embedding (GPE) technology for high-performance large package applications involving heterogeneous integration. The tailorable CTE of glass allows a reliable direct board SMT of large GPE packages that not only benefits form factor and signal speed, but also provides radical benefits to power delivery. Unlike interposers and silicon bridges, GPE packages are not bump limited and can support BEOL-like I/O densities with Silicon-like RDL at much lower costs. The fundamental limitations like die-shift and poor dimensional stability of current organic WLFO packages are addressed by parametric process improvements to reduce die-shift to <2 um while also improving the RDL surface planarity for high-yielding fine-line structures. This paper describes the fabrication process for 3D GPE, leading to demonstration of a technology using embedding of chips with all-Cu interconnections at 40um I/O pitch while also enabling double-side assembly of chips to achieve 3 levels of device integration.

Controlling Isomerization Selectivity in Chiral, Photochromic N,C-Chelate Organoboron Systems with Extended π-Conjugation.

Alkyne-functionalized chelate boron compounds with extended π-conjugation on one of the aryl groups attached to boron display thermally reversible and regioselective isomerization on the more delocalized substituent, forming base-stabilized boriranes with an intense color. Linking two of such boron chromophores through a 1,4-phenylene spacer via ethynyl moieties leads to photochemically inert molecules, while connecting them by a nonconjugated silicon bridge yields photochromic systems capable of switching at a single boron center.

Measurement of in-plane sheet thermal conductance of single-walled carbon nanotube thin films by steady-state infrared thermography

A useful and rapid method of measuring the in-plane sheet thermal conductance of single-walled carbon nanotube (SWNT) thin films by steady-state infrared thermography is proposed in this study. The SWNT thin films are suspended between the free ends of two cantilevered silicon thin plates, and the two anchored ends are kept at different but constant temperatures to achieve steady-state heat transport through this silicon–SWNT–silicon bridge in vacuum. The temperature gradient along the bridge is captured with an infrared camera. A silicon plate with known thermal conductivity serves as a reference for calculating the heat flux, so that the sheet thermal conductance of SWNT thin films can be calculated using Fourier’s law after deducting the influence of thermal radiation. The thermal conductivity of the 50-nm-thick SWNT thin film is 68.1 W m−1 K−1.

New reactivity at the silicon bridge in sila[1]ferrocenophanes.

We describe two new types of reactivity involving silicon-bridged [1]ferrocenophanes. In an attempt to form a [1]ferrocenophane with a bridging silyl cation, the reaction of sila[1]ferrocenophane [Fe(η-C5H4)2Si(H)TMP] (12) (TMP = 2,2,6,6-tetramethylpiperidyl) towards the hydride-abstraction reagent trityl tetrakis(pentafluorophenyl)borate ([CPh3][B(C6F5)4]) was explored. This yielded the unusual dinuclear species [Fe(η-C5H4)2Si(TMP·H)(η-C5H3)Fe(η-C5H4)Si(H)TMP][B(C6F5)4] [13][B(C6F5)4] in low yield. The formation of [13]+ is proposed to involve abstraction of hydride from the silicon bridge in 12 with subsequent C-H bond cleavage of a cyclopentadienyl group by the resulting electrophilic transient silyl cation intermediate. We also explored the reaction of dimethylsila[1]ferrocenophane [Fe(η-C5H4)2SiMe2] (1) with the Au(i) species AuCl(PMe3). This was found to result in addition of the Au-Cl bond across the Cpipso-Si bond to yield the ring-opened species [1'-(chlorodimethylsilyl)-ferrocenyl](trimethylphosphine)gold(i), [Fe(C5H4SiMe2Cl){C5H4Au(PMe3)}] (14). This represents the first example of ring-opening addition of a metallocenophane with a reagent possessing a transition metal-halogen bond.

Silicon-bridged triphenylamine-based organic dyes for efficient dye-sensitised solar cells

Three dyes based on a triphenylamine (TPA) moiety using a silicon bridge have been synthesised, namely CL-1D, CL-OMe and CL-SiMe. Structural benefits of long alkyl chains and electron donor group on photo conversion efficiency (PCE) of dye sensitized solar cells is discussed. A previously synthesised dye, denoted CL-1, which contained long alkyl chains and exhibited an efficiency of 6.90%, was compared with CL-SiMe, which contained shorter alkyl chains and showed and efficiency of 3.41%. A large drop in Jsc and Voc was found to be the reason for the appreciable decline in efficiency for CL-SiMe vis-à-vis CL-1. Electron donor group studies were performed using CL-1D and CL-OMe. CL-1D, which contained bulky aniline electron donor groups, showed an efficiency of 4.20%, whilst CL-OMe, featuring smaller methoxy donor groups had an efficiency of 5.50%. Theoretical UV–Vis absorption spectra were obtained for the CL-1D dye by time-dependent density functional theory (TD-DFT); the experimental and calculated values of the energy for maximum absorbance were in good agreement with experimental data.

Tuning the Photophysical Properties of Photostable Benzo[b]phosphole P-Oxide-Based Fluorophores.

We previously reported that constrained 2-phenylbenzo[b]phosphole P-oxides bearing a diphenylamino group show high photostability and thus are promising dyes for fluorescence imaging. Herein we investigated the impact of the bridging moieties on their photophysical properties. A series of benzo[b]phosphole P-oxides constrained with various carbon or silicon bridges were synthesized. All of these compounds showed significant solvatochromism in fluorescence due to the intramolecular charge-transfer character in the excited state. The dipole moments in the excited state for the carbon-bridged derivatives are slightly larger than the silicon-bridged counterparts. Nevertheless, the latter compounds showed orange-red fluorescence in polar solvents with ca. 30 nm red-shifted maxima compared to the carbon analogues. Most importantly, the assessment of their photobleaching resistance revealed that the photostability of this compound series highly relies on the steric bulkiness of the bridging moiety, and even the silicon-bridged derivative can show outstanding photostability, as far as the silicon-bridging moiety has sufficient bulkiness.

Numerical Simulation of Thermal Diffusion and Convection in Electrokinetic Microchannel Flow

: In a confined microfluidic straight channel with one heater and two detectors micro-fabricated on suspended silicon bridges, the numerical study of thermal diffusion and convection in electro-osmosis flow was carried out. Heat pulses created by the heater are transported downstream by the flow, and by performing a cross correlation between the detected and the injected signals, the linear relation between flowrate and thermal pulse's time-of-flight can be achieved, then it can provide a very accurate a linear measurement of the flowrate over long range without independence of the thermal characteristics of the fluid. These conclusions may be helpful to integration of accurate flowmeter in some portable electrokinetic micro-total-analysis systems. Key words: Electroosmosis; Thermal-pulse; Time-of-flight; Micro-flowmeter

Photodegradation of Si-PCPDTBT:PCBM active layer for organic solar cells applications: A surface and bulk investigation

The photooxidation of a polymer blend film used in efficient solar cells based on poly[(4,40-bis(2-ethylhexyl)dithieno[3,2-b:20,30- d]silole)-2,6-diylalt-(2,1,3-benzothiadiazole)-4,7-diyl], (Si-PCPDTBT) and [6,6]-phenyl-C71-butyric acid methyl (PC70BM) has been investigated. A set of experiments from complementary techniques was developed to monitor the modifications during ageing that occur not only in the bulk but also at the surface. The surface analyses were performed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the bulk analyses by UV–visible spectroscopy and infrared (IR) spectroscopy. The results reveal that the silicon bridge atom is the first target of degradation. We have identified the existence of a photooxidation profile within the 300nm thick film. Such a heterogeneous degradation was confirmed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling.

Thermal Test of an Improved Platform for Silicon Nanowire-Based Thermoelectric Micro-generators

This work reports on an improved design intended to enhance the thermal isolation between the hot and cold parts of a silicon-based thermoelectric microgenerator. Micromachining techniques and silicon on insulator substrates are used to obtain a suspended silicon platform surrounded by a bulk silicon rim, in which arrays of bottom-up silicon nanowires are integrated later on to join both parts with a thermoelectric active material. In previous designs the platform was linked to the rim by means of bulk silicon bridges, used as mechanical support and holder for the electrical connections. Such supports severely reduce platform thermal isolation and penalise the functional area due to the need of longer supports. A new technological route is planned to obtain low thermal conductance supports, making use of a particular geometrical design and a wet bulk micromachining process to selectively remove silicon shaping a thin dielectric membrane. Thermal conductance measurements have been performed to analyse the influence of the different design parameters of the suspended platform (support type, bridge/membrane length, separation between platform and silicon rim,) on overall thermal isolation. A thermal conductance reduction from 1.82 mW/K to 1.03 mW/K, has been obtained on tested devices by changing the support type, even though its length has been halved.

Dynamic mode coupling in terahertz metamaterials.

The near and far field coupling behavior in plasmonic and metamaterial systems have been extensively studied over last few years. However, most of the coupling mechanisms reported in the past have been passive in nature which actually fail to control the coupling mechanism dynamically in the plasmonic metamaterial lattice array. Here, we demonstrate a dynamic mode coupling between resonators in a hybrid metal-semiconductor metamaterial comprised of metallic concentric rings that are physically connected with silicon bridges. The dielectric function of silicon can be instantaneously modified by photodoped carriers thus tailoring the coupling characteristics between the metallic resonators. Based on the experimental results, a theoretical model is developed, which shows that the optical responses depend on mode coupling that originates from the variation of the damping rate and coupling coefficient of the resonance modes. This particular scheme enables an in-depth understanding of the fundamental coupling mechanism and, therefore, the dynamic coupling enables functionalities and applications for designing on-demand reconfigurable metamaterial and plasmonic devices.

Planar all-silicon metamaterial for terahertz applications

We propose and investigate a novel planar resonant all-silicon metamaterial. The metamaterial has a simple design. Unit cell of the periodic structure consists of silicon resonator in the form of right square prism. The prisms are connected between them by silicon bridges. The metamaterial exhibits sharp resonant reflection and transmission responses corresponding to excitation of two kinds of trapped mode regimes. These regimes are based on the first and the second magnetic dipole resonances of the unit cell.

ChemInform Abstract: Recent Progress in the Synthesis and Application of Saddle‐Shaped Cyclooctatetrathiophenes and Their Derivatives

AbstractReview: 25 refs.

Recent Progress in the Synthesis and Application of Saddle‐shaped Cyclooctatetrathiophenes and Their Derivatives

AbstractCyclooctatetrathiophene (COTh) shows a novel saddle‐shaped molecular structure, which has been applied in organic synthesis and material science. In this paper, the design and synthesis of COThs and their derivatives were described. The derivatives of COThs include mainly four types. One is isomer with different sequences of the four thiophene rings; the second is oligomer such as dimmer and dendrimer; the third is derivative functionalized by substituent groups at the four α positions; the last is the one planarized by sulfur, silicon or sulfone bridges. The applications of COThs and their derivatives in molecular muscles and field effect transistors were also discussed.

Self-Aligned Silicon Interposer Tiles and Silicon Bridges Using Positive Self-Alignment Structures and Rematable Mechanically Flexible Interconnects

A novel large-scale silicon system platform is proposed and demonstrated. In this paper, three silicon interposer tiles are aligned and mounted on a printed wiring board (PWB), and two silicon bridges are aligned and mounted on top of the three interposer tiles; each silicon bridge spans two interposer tiles. Four positive self-alignment structures and four inverted pyramid pits self-align a tile to the PWB and a bridge to two tiles. Mechanically flexible interconnects (MFI) form nonbonding electrical connections between the three interposer tiles and two silicon bridges; MFIs are fabricated on the interposer tiles. Pointy tips on the MFIs form low contact resistance with the pads on the silicon bridges. Less than 4 μm alignment error is demonstrated on a stack of silicon substrates, and <;8μm alignment error between a silicon bridge and tiles is also demonstrated on a FR4 substrate. Daisy chain and four-point measurements are performed to verify electrical connections between the three interposer tiles via MFIs and silicon bridges.

Design and photovoltaic characterization of dithieno[3,2-b:2',3'-d]silole copolymers with positioning phenyl groups.

A two-dimensional (2D) low bandgap polymer () based on dithieno[3,2-b:2',3'-d]silole (DTS) with phenyl substitution on the bridging silicon atom and thiazolo[5,4-d]thiazole (TTz) was designed and synthesized for photovoltaic applications. The impact of conjugated side chains on the optical, electrochemical and energy levels of the polymer was studied. The phenyl substituted DTS polymer exhibited a 0.16 eV down-shifted highest occupied molecular orbital (HOMO) energy level and ca. 0.1 eV narrowed bandgap in comparison to the corresponding polymers with alkyl substitution on the silicon bridge. The influence of the blend weight ratio, the PFN layer, mixed solvent, THF exposure and polar solvent treatment and thermal annealing on the performance of :PC71BM devices was studied. : PC71BM (1 : 1, weight ratio) devices delivered the highest power conversion efficiency of 2.14% by using the PFN layer and THF annealing. Thermal annealing was found to exert a negative effect on the device performance. The morphology evolution of blend films processed with different solvents explained the difference in device performance. The results indicate that phenyl substitution is an effective way to tune the HOMO and bandgap of polymer donors for enhanced photovoltaic performance with the as-demonstrated 2D-conjugated DTS structure.