Microelectronic Circuits Research Articles

Near-Infrared Sub-Bandgap All-Silicon Photodetectors: A Review

Silicon Photonics has generated an increasing interest in recent years both for optical telecommunications and for optical interconnects in microelectronic circuits. Although silicon photodiodes are excellent detectors at visible wavelengths, due to its band-gap the development of high-performance photodetectors at near infrared wavelengths has remained an imperative but unaccomplished task so far. In recent years, however, a number of near-infrared all-silicon photodetectors have been proposed and demonstrated useful in many application fields. In this paper, a review of the state of the art is presented. Devices based on mid-bandgap absorption, surface-state absorption, internal photoemission absorption and two-photon absorption are reported, their working principles elucidated and their performance discussed and compared.

An Analogous Computation of Different Techniques for The Digital Implementation of Inverter and NAND Logic Gates

Feature size reduction in microelectronic circuits has been an important contributing factor to the dramatic increase in the processing power of computer arithmetic circuits. However, it is generally accepted that MOS based circuits cannot be reduced further in feature size due to fundamental physical restrictions. Therefore, several emerging technologies are currently being investigated. Nano devices offer greater scaling potential than MOS as well as ultra low power consumption. Nano devices display a switching behaviour that differs from traditional MOS devices. This provides new possibilities and challenges for implementing digital circuits using different techniques like CNTFET,SET, FinFET etc. In this work the design of Inverter and Nand gate using CNT, SET and FinFET has been analyzed elaborately with its own advantageous of the mentioned techniques.

Embedded phase change material microinclusions for thermal control of surfaces

The performance and lifetime of sensors, microelectronic devices, mini air vehicle components and other systems can benefit from maintenance of a constant temperature profile or a local temperature that does not exceed a pre-selected, critical value during short-term transient loading events. In this work, the utility of surfaces featuring phase change materials (PCMs) encapsulated within micro-reservoirs was evaluated as a passive thermal management system for mitigation of transient temperature spikes. Patterned silicon substrates with 40 μm diameter, 10 μm deep trenches were prepared by reactive ion etching in an Ar/CF4 plasma. The features were filled with an organic phase change material possessing a high latent heat and known to undergo melting at a target operating temperature of approximately 60°C. An infrared microscope was used to produce temporally and spatially resolved temperature maps of the surface during heating. When a constant heat flux of approximately 200Wm−2 was used for uniform heating of the sample area from 50 to 75°C the PCM encapsulated materials demonstrated an isothermal plateau period lasting 5–8s near the PCM melting point. A similar plateau was also observed during cooling below the PCM melting point. From the isothermal time during heating the areal thermal energy storage density was estimated to be approximately 800Jm−2, close to that predicted by the calculated volume of PCM contained within the sample. The effects of PCM inclusions on surface temperature gradients during pulsed laser heating were also investigated. An infrared (980nm) laser at a fixed power and repetition rate was focused into a 1mm diameter beam on surfaces with and without PCM encapsulation for rapid heating (analogous to heating from resistive contacts in microelectronic circuits) of different duration from 0.5 to 5.0s. The surface temperature stayed below the desired temperature limit for 100mW laser pulses lasting up to 2s in duration. Transient temperature profiles of Si/PCM surfaces showed that micro-scale volumes of embedded phase change material stored sufficient quantities of heat to stabilize and otherwise control surface temperatures for potentially useful periods of time in selected applications.

Light Emission in Silicon from Carbon Nanotubes

The use of optics in microelectronic circuits to overcome the limitation of metallic interconnects is more and more considered as a viable solution. Among future silicon compatible materials, carbon nanotubes are promising candidates thanks to their ability to emit, modulate, and detect light in the wavelength range of silicon transparency. We report the first integration of carbon nanotubes with silicon waveguides, successfully coupling their emission and absorption properties. A complete study of this coupling between carbon nanotubes and silicon waveguides was carried out, which led to the demonstration of the temperature-independent emission from carbon nanotubes in silicon at a wavelength of 1.3 μm. This represents the first milestone in the development of photonics based on carbon nanotubes on silicon.

A hybrid magnetic/complementary metal oxide semiconductor process design kit for the design of low-power non-volatile logic circuits

Since the advent of the MOS transistor, the performance of microelectronic circuits has followed Moore’s law, stating that their speed and density would double every 18 months. Today, this trend tends to get out of breath: the continuously decreasing size of devices and increasing operation frequency result in power consumption and heating issues. Among the solutions investigated to circumvent these limitations, the use of non-volatile devices appears particularly promising. It allows easing, for example, the power gating technique, which consists in cutting-off the power supply of inactive blocks without losing information, drastically reducing the standby power consumption. In this approach, the advantages of magnetic tunnel junctions (MTJs) compared with other non-volatile devices allow one to design hybrid CMOS/magnetic circuits with high performance and new functionalities. Designing such circuits requires integrating MTJs in standard microelectronics design suites. This is performed by means of a process design kit (PDK) for the hybrid CMOS/magnetic technology. We present here a full magnetic PDK, which contains a compact model of the MTJ for electrical simulation, technology files for layout and physical verifications, and standard cells for the design of complex logic circuits and which is compatible with standard design suites. This PDK allows designers to accurately and comfortably design high-performance hybrid CMOS/magnetic logic circuits in the same way as standard CMOS circuits.

Development and characterization of nanocomposites with gold nanoparticles embedded in the nanostructured silicon substrate.

ABSTRACTIn the present work an alternative nanoparticle synthesis technique was developed, where the nanoparticles nucleate and grow inside the pores of the nanostructured porous silicon (NPS). Employing green method for the nanoparticle synthesis, yeast extract is used as a reducing agent. The porous layers were prepared by electrochemical etching of Boron-doped (100) Si substrate (0.01-0.02Ohm·cm). The NPS support was immersed into the reactive colloid for different times, then withdrawn, cleaned and dried. SEM and XRD measurements were carried out to characterize the NPS substrate and the immobilized catalyst nanoparticles. EDX mapping shows a homogeneous deposition of nanoparticles on the porous support. The average particle size, calculated from XRD diffractograms (using the Scherrer`s formula), was found between 6 to 10 nm. This method provides a good incorporation and distribution of nanoparticles, also an alternative environment-friendly technique to develop catalytic devices fabricated on silicon substrate with an additional advantage of being integrated with the silicon based microelectronic circuits.

BEHAVIORAL MODEL OF SYMMETRICAL MULTI-LEVEL T-TREE INTERCONNECTS

An accurate and behavioral modeling method of symmet- rical T-tree interconnect network is successfully investigated in this paper. The T-tree network topology understudy is consisted of ele- mentary lumped L-cells formed by series impedance and parallel ad- mittance. It is demonstrated how the input-output signal paths of this single input multiple output (SIMO) tree network can be reduced to single input single output (SISO) network composed of L-cells in cascade. The literal expressions of the currents, the input impedances and the voltage transfer function of the T-tree electrical interconnect via elementary transfer matrix products are determined. Thus, the exact expression of the multi-level behavioral T-tree transfer function is established. The routine algorithm developed was implemented in Matlab programs. As application of the developed modeling method, the analysis of T-tree topology comprised of difierent and identical RLC-cells is conducted. To demonstrate the relevance of the model established, lumped RLC T-tree networks with difierent levels for the microelectronic interconnect application are designed and simulated. The work ∞ow illustrating the guideline for the application of the rou- tine algorithm summarizing the modeling method is proposed. Then, 3D-microstrip T-tree interconnects with width 0.1m and length 3mm printed on FR4-substrate were considered. As results, a very good agreement between the results from the reduced behavioral model pro- posed and SPICE-computations is found both in frequency- and time- domains by considering arbitrary binary sequence \01001100 with 2Gsym/s rate. The model proposed in this paper presents signiflcant beneflts in terms of ∞exibility and very less computation times. It can be used during the design process of the PCB and the microelectronic circuits for the signal integrity prediction. In the continuation of this

Effect of Laser-Induced Etching Process on Porous Structures

Various features of Silicon micro and nanostructures have been produced by lasers. Laser micromachining of silicon wafer has been conducted to fabricate devices for microelectronic circuits. The laser beam initiates a chemical reaction between the silicon and HF acid to synthesize porous layers by a laser-induced etching process. It is found that the etching rate increases for longer laser wavelengths when CW lasers are used and could also be used to drill micro holes in the silicon wafer when higher laser power densities are used. While Q-switched Nd:YAG laser could be employed to produce ordered nanostructures. It is found that laser parameters are adequate to produce and control the micro/nanostructure characteristics. The surface morphology investigation reveals formation of porous layers of various structures and different laser parameters were affected differently on the surface morphology. Moreover, the SEM statistics imply that high pore density of smaller average pores diameters of 3μm are obtained when the HF concentration diluted to 30%. Furthermore, gratings of submicrons scale can be made when proper processing parameters are selected precisely. Experimental analysis has been carried out to characterize the microstructured surface using computer software.

A USB-based electrochemical biosensor prototype for point-of-care diagnosis

A portable, USB-based electrochemical biosensor prototype for point-of-care testing (POCT) was designed, fabricated, and tested with a model analyte. The device implements cyclic voltammetry (CV) measurements by means of a portable potentiostat in conjunction with a miniaturized electrochemical cell. The microelectronic circuit consists of a single-supply potentiostat and I/V converter, an analog-to-digital converter (ADC), and a microcontroller unit (MCU); powered and controlled entirely by USB the device is suitable for field testing alongside any portable personal computer (PC). The electrochemical cell contains sixteen test chambers encompassing disposable gold working electrodes fabricated on standard glass slides. The gold working electrodes were patterned using photolithographic techniques while platinum and silver–silver chloride wires served as the counter and reference electrodes, respectively. System performance was evaluated by performing lysozyme detection using surface-bound anti-lysozyme DNA aptamers; the results are comparable to those obtained using a commercial electrochemical system.

Guest Editors' Introduction: Asynchronous Design Is Here to Stay (and Is More Mainstream Than You Thought)

Asynchronous or clockless design is poised to play a key role in alleviating fundamental challenges of current and future microelectronic circuits and systems. Asynchronous design abandons clocking in favor of handshaking, thereby enhancing design modularity, reducing unnecessary switching activity, and accommodating delay variation. This special issue of IEEE Design & Test presents seven articles that highlight recent advances in the field of asynchronous design, its impact on current industrial practice, and potential for use in future technologies.

Microelectronic neural bridge for signal regeneration and function rebuilding over two separate nerves

According to the feature of neural signals, a micro-electronic neural bridge (MENB) has been designed. It consists of two electrode arrays for neural signal detection and functional electrical stimulation (FES), and a microelectronic circuit for signal amplifying, processing, and FES driving. The core of the system is realized in 0.5-μm CMOS technology and used in animal experiments. A special experimental strategy has been designed to demonstrate the feasibility of the system. With the help of the MENB, the withdrawal reflex function of the left/right leg of one spinal toad has been rebuilt in the corresponding leg of another spinal toad. According to the coherence analysis between the source and regenerated neural signals, the controlled spinal toad's sciatic nerve signal is delayed by 0.72 ms in relation to the sciatic nerve signal of the source spinal toad and the cross-correlation function reaches a value of 0.73. This shows that the regenerated signal is correlated with the source sciatic signal significantly and the neural activities involved in reflex function have been regenerated. The experiment demonstrates that the MENB is useful in rebuilding the neural function between nerves of different bodies.

Harmonic generation in silicon nitride ring resonators

We demonstrate second- and third-harmonic generation in a centrosymmetric CMOS-compatible material using ring resonators and integrated optical waveguides. The χ(2) response is induced by using the nanoscale structure of the waveguide to break the bulk symmetry of silicon nitride (Si3N4) with the silicon dioxide (SiO2) cladding. Using a high-Q ring resonator cavity to enhance the efficiency of the process, we detect the second-harmonic output in the visible wavelength range with milliwatt input powers at telecom wavelengths. We also observe third-harmonic generation from the intrinsic χ(3) susceptibility of the silicon nitride. Phase matching of the harmonic processes occurs due to the near coincidence of indices of refraction of the fundamental mode at the pump frequency and the corresponding higher-order modes of the harmonic fields.

Capteur ECG intelligent pour la synchronisation des séquences en IRM et le monitorage des patients

Cardiac magnetic resonance imaging (MRI) has become an essential tool to diagnose several cardiac diseases. This technique is highly dependant on the accuracy of electrocardiogram (ECG) signals and on the sequence synchronization algorithm. Our goal was the development of a smart MR ECG, totally compatible with the MR environment for: (1) robust synchronization of MR sequences, including cases of pathologic ECG, rhythmic disorders, low amplitude ECG for patients who are excluded nowadays and (2) safe and continuous patient monitoring working for all MR examinations with detection of emergency situations. To achieve these objectives, an ECG amplifier and a 3D magnetic field sensor have been developed in microelectronic technology (chip). We have associated motion sensors to acquire respiration displacement during an MRI exam. These sensors give a correct representation of the patient breathing allowing advanced image reconstruction methods. The designed microelectronic circuits are totally non magnetic, and can be placed in the imaging field of view. A dedicated ECG database was created to evaluate and validate new signal processing techniques as, independent component analysis, wavelet decomposition and Bayesian approaches. These methods allow to remove almost all artifacts on the ECG signal to achieve a better diagnosis and smart sequence synchronization. Classification of rhythmic disorder was not totally achieved.

Plasmonic Nanofabrication by Long-Range Excitation Transfer via DNA Nanowire

Driven by the demand for ongoing integration and increased complexity of today's microelectronic circuits, smaller and smaller structures need to be fabricated with a high throughput. In contrast to serial nanofabrication techniques, based, e.g., on electron beam or scanning probe methods, optical methods allow a parallel approach and thus a high throughput. However, they rarely reach the desired resolution. One example is plasmon lithography, which is limited by the utilized plasmonic metal structures. Here we show a new approach extending plasmonic lithography with the potential for a highly parallel nanofabrication with a higher level of complexity based on nanoantenna effects combined with molecular nanowires. Thereby femtosecond laser pulse light is converted by Ag nanoparticles into a high plasmonic excitation guided along attached DNA structures. An underlying poly(methyl methacrylate) (PMMA) layer acting as an electron-sensitive resist is so structured along the former DNA position. This apparently DNA-guided effect leads to nanometer grooves reaching even micrometers away from the excited nanoparticle, representing a novel effect of long-range excitation transfer along DNA nanowires.

Electric Drives and Microelectronic Circuits [review of "Microelectronic Circuits: Analysis and Design, 2nd Edition (Rashid, M.H. 2011)

Electric Drives and Microelectronic Circuits [review of "Microelectronic Circuits: Analysis and Design, 2nd Edition (Rashid, M.H. 2011)

Electric Drives and Microelectronic Circuits [review of "Model-Based PredictiveControl of Electric Drives" (Linder, A., et al; 2010)

Electric Drives and Microelectronic Circuits [review of "Model-Based PredictiveControl of Electric Drives" (Linder, A., et al; 2010)

Mechanistic considerations of low temperature hydrogen-based plasma etching of Cu

A simple plasma-based, low temperature etch process is described, which allows subtractive etching of copper (Cu) films and thereby offers an alternative to damascene technology for microelectronic and integrated circuit device fabrication. Hydrogen (H2)-based plasma etching of blanket and SiO2 masked Cu thin films is performed in an inductively coupled plasma reactor at temperatures below room temperature. This process achieves anisotropic Cu features and an etch rate of ∼13 nm/min. Although Ar and He are more efficient sputter gases, Cu etching in these plasma atmospheres displays lower etch rates than those observed with H2 plasmas. Moreover, anisotropy degraded with enhanced ion bombardment due to mask ablation. Cu etch rate and patterning results are consistent with an etch process that involves both chemical and physical characteristics. Specifically, the combination of ultraviolet photon impingement, ion bombardment, and hydrogen interaction with Cu surfaces appears to be responsible for the efficient removal of Cu in low temperature H2-based plasma environments.

PECA

Wireless sensor networks (WSN) have emerged in many applications as a platform to collect data and monitor a specified area with minimal human intervention. The initial deployment of WSN sensors forms a network that consists of randomly distributed devices/nodes in a known space. Advancements have been made in low-power micro-electronic circuits, which have allowed WSN to be a feasible platform for many applications. However, there are two major concerns that govern the efficiency, availability, and functionality of the network—power consumption and fault tolerance. This paper introduces a new algorithm called Power Efficient Cluster Algorithm (PECA). The proposed algorithm reduces the power consumption required to setup the network. This is accomplished by effectively reducing the total number of radio transmission required in the network setup (deployment) phase. As a fault tolerance approach, the algorithm stores information about each node for easier recovery of the network should any node fail. The proposed algorithm is compared with the Self Organizing Sensor (SOS) algorithm; results show that PECA consumes significantly less power than SOS.

Direct Printing for Next Generation High Density Packaging

Next generation micro-packaging will feature a number of advances in high density techniques, including more components in a smaller volume. New techniques for metallization, passives, antennas, solders, and adhesives will be required. The key factor for these will be size constraints. Micro-dispensing can print a number of materials to include dielectrics, ruthenates, metallics, solder, and adhesives. Those with experience in micro-dispensing recognize the size limitation using a dispensing approach and understand that the hope of achieving smaller line widths, smaller pad sizes, and precise placement of the material is not feasible. nScrypt has demonstrated the ability to considerably shrink the line widths and dots from traditional micro-dispensing, thus enabling the next generation packaging and increasing the component count in the same or less volume. Micro-dispensing solder dots, precisely placing narrow adhesive lines and potentially directly printing resistors and antennas to replace standard pick and place and connectorized antennas will be demonstrated to reduce the size and volume for high micro-electronic circuits. In addition to the new and enabling reduced volume approach, nScrypt will also demonstrate how the speed of this approach will rival traditional high volume screen printing and other masking technologies, thus making this a viable manufacturing tool for micro-packaging.

Superhydrophobic Coatings on Electronic Components

Superhydrophobic coatings provide exceptional protection to electrical circuits, switches, and other electrical devices which operate in wet environments, such as food processing plants or outdoor applications. Among various electrical device applications, electric motors and electrical switches have been successfully tested in the field at two food processors for nearly 20 months with exceptionally good results. Coated microelectronic circuit board has been in operation without any incidence for over 1 year.