Device Topology Research Articles

Basic approaches to photoresist mask formation modeling in computational lithography

The article gives an overview of the main currently used models for the formation of photoresist masks and the problems in which they are applied. The main stages of «full physical» modeling of mask formation are briefly considered in the case of both traditional DNQ photoresists and CA photoresists. The concept of compact models (VT5 and CM1), which predict the contour of the resist mask for a full-sized device topology is considered. Examples of some calculations using both full physical modeling and compact models are given. Using a full physical modeling of the resist mask formation the lithographic stack was optimized for a promising technological process. The optimum thickness ratios for the binary BARC used in the water immersion lithographic process are found. The problem of determining the optimal number of calibration structures that maximally cover the space of aerial image parameters was solved. To solve this problem, cluster analysis was used. Clustering was carried out using the k-means method. The optimal sample size was from 300 to 350 structures, the mean square error in this case is 1.4 nm, which slightly exceeds the noise of the process for 100 nm structures. Using SEM images for calibrating the VT5 model allows reducing the standard error of 40 structures to 1.18 nm.

Non-Linear Capacitance of Si SJ MOSFETs in Resonant Zero Voltage Switching Applications

The parasitic capacitances of modern Si SJ MOSFETs are characterized by their non-linearity. At high voltages the total stored energy Eoss(VDC) in the output capacitance Coss(v) differs substantially from the energy in an equivalent linear capacitor Coss(tr) storing the same amount of charge. That difference requires the definition of an additional equivalent linear capacitor Coss(er) storing the same amount of energy at a specific voltage. However, the parasitic capacitances of current SiC and GaN devices have a more linear distribution of charge along the voltage. Moreover, the equivalent Coss(tr) and Coss(er) of SiC and GaN devices are smaller than the ones of a Si device with a similar Rds,on. In this work, the impact of the non-linear distribution of charge in the performance and the design of resonant ZVS converters is analyzed. A Si SJ device is compared to a SiC device of equivalent Coss(tr), and to a GaN device of equivalent Coss(er), in single device topologies and half-bridge based topologies, in full ZVS and in partial or full hard-switching. A prototype of 3300 W resonant LLC DCDC converter, with nominal 400 V input to 52 V output, was designed and built to demonstrate the validity of the analysis.

Impact of Kinematic Structure on the Force Displayability of Planar Passive Haptic Devices.

Haptic devices containing passive actuators, such as controllable brakes or dampers, are an attractive alternative to their motor-driven counterparts due to intrinsic stability and improved impedance bandwidth. Passive actuators cannot generate energy and, therefore, the output force can only oppose the applied velocity. In the same way the kinematic structure of traditional manipulators is designed to maximize dexterity and manipulability, one must consider adapting the device topology to optimize force displayability when designing passive actuators. This article introduces a set of metrics to evaluate and compare the performance of 2-degree-of-freedom (DOF) serial and parallel passive haptic devices. These metrics consider the impact of the kinematic structure on the force displayability according to the directions of the device velocity and desired force. Applying these metrics to nine manipulators revealed that: 1.) serial manipulators can generate passive forces in all directions equally regardless of the link length ratio; 2.) the base link length of five-bar parallel manipulators strongly influences passive force displayability; 3.) five-bar parallel manipulators with the base link length of zero can generate the widest range of passive forces when all links have the same length. The novel performance metrics presented in this paper can aid in the design of 2-DOF passive haptic devices.

Optimization of the Alignment Method for an Electric Vehicle Magnetic Field Wireless Power Transfer System Using a Low-Frequency Ferrite Rod Antenna

The establishment of international and regional standards for electric vehicle (EV) magnetic field wireless power transfer (MF-WPT) systems started in 2010 by the Society of Automotive Engineers (SAE). In the meantime, the EV MF-WPT standardization has been focused on primary device and secondary device topology. Recently, the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), and SAE have begun describing the communication and alignment techniques for EV MF-WPT. In this paper, we present a fine positioning method using a low-frequency (LF) signal, as mentioned in IEC 61980 and SAE J2954. Through modeling and simulation, we optimized a LF ferrite rod antenna (FRA) for EV MF-WPT fine positioning. We also found the optimal arrangement of LF-FRAs on primary device and secondary device Finally, we used a test bench to experiment and check the results of our proposal.

New DG FeFET topology with enhanced SS and non-hysteretic behavior

In this paper we present a simulation study of a novel Double-Gate (DG) Ferroelectric FET (Fe-FET) architecture, exhibiting a subthreshold swing well below 60 mV/dec with a hysteresis-free behavior. The new device topology is based on the interposition of a floating gate between the ferroelectric layer and the gate oxide. The floating gate can be extended above the source and drain regions, so that its capacitance can be suitably optimized to ensure device stability. We found that both the overlap capacitance and quantum confinement are beneficial for the amplification factor. The ION improvement over the standard DG MOSFET turns out to be 23.7×, with no degradation of the intrinsic transit time.

Controlled Spin-Wave Transport in a Magnon-Crystal Structure with a One-Dimensional Array of Holes

Spin-wave transport in a lateral system of microwaveguides coupled to each other through a magnonic crystal structure with a one-dimensional array of holes has been analyzed. Mechanisms of controlling a spin-wave signal at the tangential magnetization of the structure have been studied by the micromagnetic simulation and Brillouin spectroscopy. It has been shown that the anisotropy of the shape in region of coupling of spin waves propagating through isolated channels can be effectively changed under the variation of the magnetization angle of the structure, which allows controlling spatial and frequency selective regimes of spin-wave transport. The proposed structure can be used as a functional element of interconnections in planar topologies of magnonic networks and devices for parallel processing of a signal based on them.

A Reliable Device Topology for ZnO Nanowire-based Gas Sensors

A Reliable Device Topology for ZnO Nanowire-based Gas Sensors

Variation of device topology for material simplification as three‐dimensional transformation optics methodology

A three-dimensional (3-D) transformation optics (TO) methodology is presented using polyhedral meshing and homogeneous materials, in which, the topology of the device is varied, in order to achieve material simplification. The device is divided into a minimal number of polyhedral segments, and a linear transformation is applied to each polyhedron. The polyhedrons and transformations are tried to be chosen so that the volume is conserved through the transformation, and if possibly, some transformed materials are equivalent to free space. A few 3-D waveguide coupler and carpet cloak problems are solved to demonstrate and evaluate the proposed methodology. For instance, it is shown that a right-angle 3-D rectangular waveguide bend can be designed using only one two-dimensional (2-D) homogeneous material. Also, resize couplers are designed using only one or two 2-D homogeneous materials. A carpet cloak is demonstrated which uses only two material types, filling five polyhedral meshing segments. Similar problems would have required much larger number of meshing segments and material types, using previous methods. Therefore, using the proposed methodology, 3-D TO-based guiding and cloaking devices will be more feasible. Furthermore, a 3-D finite difference time domain (FDTD) method is developed to verify the results of some examples.

Piezoelectric-on-Silicon MEMS Lorentz Force Lateral Field Magnetometers.

This paper describes the realization of piezoelectric-on-silicon lateral field Lorentz force magnetometers (LFMs) that target operation in ambient pressure instead of vacuum. Specifically, we describe two device topologies based on the out-of-plane resonant vibration modes. The first is based on a classic cantilever while the other is based on a corner-flapping square plate. In both topologies, piezoelectric transduction is exploited to enhance the sensitivity of the device compared to prevailing approaches to microelectromechanical system (MEMS) LFMs based on capacitive output interfaces. We show that the responsivity of the corner-flapping square plate topology (12026 ppm/T) is 8.5 times higher than a state-of-the-art lateral field LFM based on a capacitive output interface even without relying on vacuum. We here define responsivity as the output sense current per unit magnetic field density normalized over the input excitation current.

On the Progress Made in GaN Vertical Device Technology

Silicon technology enabled most of the electronics we witness today, including power electronics. However, wide bandgap semiconductors are capable of addressing high-power electronics more efficiently compared to Silicon, where higher power density is a key driver. Among the wide bandgap semiconductors, silicon carbide (SiC) and gallium nitride (GaN) are in the forefront in power electronics. GaN is promising in its vertical device topology. From CAVETs to MOSFETs, GaN has addressed voltage requirements over a wide range. Our current research in GaN offers a promising view of GaN that forms the theme of this article. CAVETs and OGFETs (a type of MOSFET) in GaN are picked to sketch the key achievements made in GaN vertical device over the last decade.

Hadoop MapReduce for Mobile Clouds

The new generations of mobile devices have high processing power and storage, but they lag behind in terms of software systems for big data storage and processing. Hadoop is a scalable platform that provides distributed storage and computational capabilities on clusters of commodity hardware. Building Hadoop on a mobile network enables the devices to run data intensive computing applications without direct knowledge of underlying distributed systems complexities. However, these applications have severe energy and reliability constraints (e.g., caused by unexpected device failures or topology changes in a dynamic network). As mobile devices are more susceptible to unauthorized access, when compared to traditional servers, security is also a concern for sensitive data. Hence, it is paramount to consider reliability, energy efficiency and security for such applications. The MDFS (Mobile Distributed File System) [1] addresses these issues for big data processing in mobile clouds. We have developed the Hadoop MapReduce framework over MDFS and have studied its performance by varying input workloads in a real heterogeneous mobile cluster. Our evaluation shows that the implementation addresses all constraints in processing large amounts of data in mobile clouds. Thus, our system is a viable solution to meet the growing demands of data processing in a mobile environment.

Improved oxide field and switching performance obtained in a CoolSiCTM trench MOSFET by incorporating the superjunction concept

The superjunction concept is incorporated in a CoolSiC trench MOSFET structure to investigate its potential on static and dynamic characteristics using two-dimensional simulations. The effects of device topology on the breakdown voltage and specific on resistance (Rsp,on) are studied. Optimized results show an improvement in the breakdown voltage by 34% and Rsp,on by 30%, compared with the standard CoolSiC MOSFET structure. Furthermore, a marginal improvement in the off state trench corner electric field is obtained. The switching behavior using a clamped inductive circuit showed improved turn on and turn off losses at 900 V, 4 A. After the addition of stray inductance, we observed a less than 0.2 V shift in the gate voltage waveform. Simulation results indicate that the proposed structure has shown improved device characteristics and enhanced turn off performance owing to a reduction in gate charge (Qg) and Miller capacitance.

Temperature Cross-Sensitivity of AlN-Based Flexural Plate Wave Sensors

In this paper, we investigate the temperature cross-sensitivity of aluminum nitride (AlN)-based flexural plate wave devices for sensing applications in contact with liquids. In our improved device topology, the interdigital transducers are designed as a buried electrode, and thus, are electrically shielded, enabling full immersion of the sensor into the liquid. The fabricated devices showed a mass sensitivity of 240 cm2/g for loading with deionized water which is in good agreement with the theoretical predictions. The temperature coefficient of frequency (TCF) was evaluated for devices with initially compressive and tensile stressed AlN layers. Devices with compressive film stress exhibited a TCF of −62 ppm/K to −28 ppm/K, while the devices with tensile film stress showed an increased TCF of −391 ppm/K to −72 ppm/K. It is shown that variations in in-plane tension are mainly accountable for the increased TCF, while the lower TCF is primarily caused by material softening.

Overlapping‐Gate Organic Light‐Emitting Transistors

AbstractA light‐emitting transistor in which two gates, separated by an insulator, partially overlap in the center of the device is proposed. By accumulating charge carriers in dedicated transport layers, each gate independently controls charge injection into the emissive layer sandwiched between the transport layers. This structure combines the advantages of pinned light emission in the center of the channel, gapless charge transport into the recombination zone, and controlled balance of electron and hole concentration at the edges of the emissive layer for any chosen current density. High‐performance devices with overlapping gates are demonstrated: Using a red fluorescent emitter, high external quantum efficiency (5.7%) is conserved up to the highest luminance (2190 cd m−2). A comprehensive optoelectronic device model is proposed that verifies the measured characteristics and confirms that efficiency is highest with balanced charge transport. This device topology opens perspectives in the development of bright thin film light sources driven at high current densities.

Piezoelectric-on-Silicon Square Wine-Glass Mode Resonator for Enhanced Electrical Characterization in Water

We describe a piezoelectric square wine-glass (SWG) mode micromechanical resonator as a unique device topology for liquid phase sensing applications that offers enhanced quality (Q)-factor in water over other common contour modes. We show a Q-factor in water of 377 for 14.08-MHz SWG mode resonator (mean of multiple measurements), which is one of the highest Q-factors among piezoelectric resonators tested when covered in a fluid. We show that the Q-factor in water of the SWG mode increases much more significantly with a reduction in resonator size relative to the square-extensional (SE) mode, such that the Q-factor the SWG mode can be almost twice of the SE mode. We present an analytical model for the mode shape of the proposed SWG resonators and their effective electromechanical coupling factor $({k}_{\text {eff}}^{{2}})$ . Due to the enhanced Q-factor in water, reasonable ${k}_{\text {eff}}^{{2}}$ , and feedthrough cancelation (using fully differential transduction with the fluid loaded from the backside of the device), we show that a strong resonant peak of 29.8 dB is obtainable in water.

Development and Investigation of Three Different Topologies of Devices for Sensing of Moisture Traces

This work evaluates the development and investigation of three different topologies devices for low moisture level sensing using small electrode systems interdigitated with capacitive properties. Such devices have a millimeter scale and have a simple constructive process. The different sensors developed and tested were submitted to a process with duration of 240 minutes, with intervals of temperature changes and alteration of the conditions of the environment in which they were exposed through the use of nitrogen gas without presence of any moisture (N2) and nitrogen gas with an amount of moisture (N2 with 300 ppmv H2O). This process was aimed at the analysis of changes in the capacitance values of these sensors as temperature and humidity levels changed.

Common Mode Noise Propagation and Effects in a Four-Wheel Drive Electric Vehicle

New topologies of electric car use high power switching devices which must be integrated with a growing range of electronic systems in small places. A good performance of the car relies on the electromagnetic compatibility among these systems, which requires the characterization of the noise and interferences present in the system. To characterize the noise, both emission and susceptibility issues as well as coupling mechanisms must be studied. This paper presents the work performed for the electromagnetic mapping of a four-wheel fully electric car, which involves both simulation and experimental measurements. It has been carried out within the E-VECTOORC project (FP7-INFSO-284708), in collaboration with car manufacturers such as Jaguar Land Rover and Skoda.

Combined Exposure Ratio Evaluation for Micro-Power Devices

The exposure ratio of multiple micro-power devices is difficult to evaluate in terms of the choices of measure point and public exposure control limit due to various frequencies, antenna transmit powers, and device topologies; whereas the traditional multi-device evaluation method was found unable to achieve consistent and rational results. In order to address these challenges, a combined radiation device mode is introduced to simplify the choice of measure point, and a convert algorithm is proposed to determine public exposure control limit in any distance. The adjusting factors are added to the convert algorithm to improve its position consistency and limit rationality, and a neural network is designed to optimize its nonlinear coefficients. Finally, the radiation pressure tests in lineal and rectangular topologies are provided to corroborate our studies.

Volumetric flow rate in simulations of microfluidic devices

In this work, we examine the volumetric flow rate of microfluidic devices. The volumetric flow rate is a parameter which is necessary to correctly set up a simulation of a real device and to check the conformity of a simulation and a laboratory experiments [1]. Instead of defining the volumetric rate at the beginning as a simulation parameter, a parameter of external force is set. The proposed hypothesis is that for a fixed set of other parameters (topology, viscosity of the liquid, …) the volumetric flow rate is linearly dependent on external force in typical ranges of fluid velocity used in our simulations. To confirm this linearity hypothesis and to find numerical limits of this approach, we test several values of the external force parameter. The tests are designed for three different topologies of simulation box and for various haematocrits. The topologies of the microfluidic devices are inspired by existing laboratory experiments [3 - 6]. The linear relationship between the external force and the volumetric flow rate is verified in orders of magnitudes similar to the values obtained from laboratory experiments.

A new class of variable capacitance generators based on the dielectric fluid transducer

This paper introduces the novel concept of dielectric fluid transducer (DFT), which is an electrostatic variable capacitance transducer made by compliant electrodes, solid dielectrics and a dielectric fluid with variable volume and/or shape. The DFT can be employed in actuator mode and generator mode. In this work, DFTs are studied as electromechanical generators able to convert oscillating mechanical energy into direct current electricity. Beside illustrating the working principle of dielectric fluid generators (DFGs), we introduce different architectural implementations and provide considerations on limitations and best practices for their design. Additionally, the proposed concept is demonstrated in a preliminary experimental test campaign conducted on a first DFG prototype. During experimental tests a maximum energy per cycle of and maximum power of has been converted, with a conversion efficiency up to 30%. These figures correspond to converted energy densities of with respect to the displaced dielectric fluid and with respect to the mass of the solid dielectric. This promising performance can be largely improved through the optimization of device topology and dimensions, as well as by the adoption of more performing conductive and dielectric materials.