Interconnect Lines Research Articles

Assessment of traveling wave-based functions in inverter-based resource interconnecting lines

In this paper, the behavior of traveling waves (TWs) on transmission lines which interconnect inverter-based resources (IBRs) is investigated, assessing the performance of well-known TW functions applied in protection and fault location schemes. To do so, traditional synchronous generators and wind turbine-based IBRs of types III and IV are investigated, allowing comparative studies regarding the shape of fault-induced transients measured at the monitored line terminals. Then, the impacts of typical terminations of IBR-interconnecting lines on the classical double-ended TW-based fault location method, as well as on directional, overcurrent and differential TW-based protections are analyzed, highlighting the effects of busbar and transformer stray capacitances on the performance of these functions. The obtained results reveal that TW solutions are promising for IBR-interconnecting lines. However, a significant influence of busbar and transformer stray capacitances on the performance of TW functions is also identified, revealing the need for taking these capacitances into account during the definition of settings used in TW protection and fault location schemes.

Exploring the potential of a machine learning-based methodology for fault classification in inverter-based resource interconnection lines

Considering the increasing penetration of Inverter-Based Resources (IBRs) in electrical power systems, and the observed impacts on protection and fault diagnosis functions due to their atypical operational characteristics, this paper proposes a fault classification methodology that presents high efficiency for IBR interconnection lines. The fault classification methodology, which combines Discrete Wavelet Transform (DWT) with Machine Learning (ML) tree or rule-based methods, is presented and evaluated. The generalization ability of this methodology as well as the influence of the number and representativeness of training instances on the percentage of correct fault classifications are scrutinized. The proposed methodology was also evaluated for systems with different voltage levels, noisy signals, and considering variations in fault types, locations, inception angles, and resistances, in addition to different grid short circuit levels and IBR controls. Finally, comparisons are made with state-of-the-art fault classification methods to prove the impact of IBRs on these methods and to highlight the superiority of the proposed methodology. For the case studies, two systems with different voltage levels and typical connection topologies of IBRs to the grid are modeled in the PSCAD software, and several contingency scenarios are simulated.

Systematic characterization for RF small-signal parameter extraction of 28 nm FDSOI MOSFETs up to 110 GHz

A systematic RF characterization and small-signal parameter extraction for 28 nm fully depleted silicon on insulator (FDSOI) MOSFETs is presented in this paper. Two-step and hybrid de-embedding methodologies have been applied and compared for the accurate de-embedding of the on-chip RF test pads and access interconnect line elements. To avoid the accumulated error from the de-embedding for the small signal model of the FDSOI MOSFET, an error check criterion is adopted and utilized. Then, the complete extrinsic and intrinsic small-signal parameters of the device were extracted at multi-bias points based on the combination of direct extraction and linear regression approaches. For the extrinsic parameter extraction, the substrate-related parasitic elements and the extrinsic resistance components have been extracted. For the intrinsic small-signal parameter extraction, a complete model is presented and applied for direct extraction of the small-signal parameters. To verify the validity of the proposed modeling approach and the employed small-signal model, the S-parameters of a 28 nm FDSOI NMOS device with a 16 × 1 μm gate width were measured and characterized. From the comparison of the measured and modeled data, it is found that the proposed de-embedding and small-signal model provide an accurate characterization of RF parameter extraction for the FDSOI MOSFETs up to 110 GHz.

Comparison of Precursors for Self-Assembled Monolayers as Cu Barriers

Self-assembled monolayers (SAMs) are the emerging materials as the candidate of barriers for application in back-end-of–line interconnects in advanced integrated circuits. In this study, SAMs derived from organic molecules with different structures are compared in terms of electrical characteristics, Cu diffusion inhibition, and Cu–SiO2 adhesion promotion. Experimental results indicated that all SAMs formed in this study enhanced the breakdown filed of SiO2 film, promote Cu–SiO2 adhesion, and prevent Cu-silicate formation under thermal annealing. Among the studied SAMs, APTMS–SAM derived from 3-aminopropyltrimethoxysilane (APTMS) has the most pronounced enhancement. Moreover, APTMS–SAM blocks the drift of Cu under electrical stress. The terminal group −NH2 attached to Cu layer in the APTMS is the key for the improvement.

Distributed Control Algorithm for DC Microgrid Using Higher-Order Multi-Agent System

During the last decade, DC microgrids have been extensively researched due to their simple structure compared to AC microgrids and increased penetration of DC loads in modern power networks. The DC microgrids consist of three main components, that is, distributed generation units (DGU), distributed non-linear load, and interconnected power lines. The main control tasks in DC microgrids are voltage stability at the point of common coupling (PCC) and current sharing among distributed loads. This paper proposes a distributed control algorithm using the higher-order multi-agent system for DC microgrids. The proposed control algorithm uses communication links between distributed multi-agents to acquire information about the neighbors’ agents and perform the desired control actions to achieve voltage balance and current sharing among distributed DC loads and DGUs. In this research work, non-linear ZIP loads and dynamical RLC lines are considered to construct the model. The dynamical model of the power lines and DGU are used to construct the control objective for each distributed DGU that is improved using the multi-agent system-based distributed current control. The closed-loop stability analysis is performed at the equilibrium points, and control gains are derived. Finally, simulations are performed using MATLAB/Simulink environment to verify the performance of the proposed control method.

A Multiscale Simulation Study of the Structural Integrity of Damascene Interconnects in Advanced Technology Nodes

The structural stability of tight-pitched (18 nm and below) damascene interconnects for back-end-of-line (BEOL) technologies are analyzed using force-field-based molecular dynamics simulations and finite-element modeling. At these pitches surface energy-dominated effects come into the picture, which lead to structural instability. The candidate metals analyzed are beyond copper (Cu) interconnect metals-ruthenium (Ru), cobalt (Co), and tungsten (W); and Cu is analyzed for reference. Cohesive traction and normal bonding energy are calculated using force-field-based molecular dynamics simulations and then fed as input to a finite-element analysis (FEA) tool, where their dependence on the physical dimensions of the interconnect lines is studied. The parameters studied for the BEOL structures are sidewall angle, aspect ratio, the internal stress of the metal, and modulus of elasticity of the dielectric material around the metal to understand the sensitivity of these parameters to the structural stability of the interconnects. We observe that a lower aspect ratio and higher modulus of elasticity of the dielectric results in stable structures whereas, intrinsic stress of the metal and side wall angle have a minor impact on the overall stability. The stability is analyzed at the seed-layer deposition step and based on this study, Co is the most stable alternate metal amongst Ru, Co, and W.

СODING TO REDUCE THE ENERGY OF DATA MOVEMENT

The problem of reducing power dissipation in global interconnection lines while maintaining high performance is considered in the paper. High switching activity leads to significant communication losses due to communication capacitances between long lines. New byte-addressed non-volatile memory technologies, such as phase change memory, enable systems with large persistent memory, improving reliability and potentially reducing power consumption. However, these technologies only support a limited number of write operations over the lifetime per cell, and consume most of their power when the state of a bit changes during a write. Low power coding techniques are required to reduce switching activity during device-to-device or on-chip communications. The purpose of the article is to develop a method for constructing a set of unit distance codes, analyzing their characteristics and choosing codes that satisfy the given properties. The address bus coding methods with the least switching activity are considered. To reduce dynamic energy losses in the address bus and minimize communication losses between closely spaced lines, Gray code is used, which has a number of disadvantages. Conclusions. The type of codes that have the same properties as Gray codes, i.e. unit distance codes, is determined. A method for constructing a set of unit distance codes, analyzing their characteristics, and choosing codes that satisfy the given properties has been developed. By using the entire set of codes, developers have more choices than using only Gray codes, and this leads to better results.

Graded Mxene-Doped Liquid Metal as Adhesion Interface Aiming for Conductivity Enhancement of Hybrid Rigid-Soft Interconnection.

Hybrid rigid-soft electronic system combines the biocompatibility of stretchable electronics and the computing capacity of silicon-based chips, which has a chance to realize a comprehensive stretchable electronic system with perception, control, and algorithm in near future. However, a reliable rigid-soft interconnection interface is urgently required to ensure both the conductivity and stretchability under a large strain. To settle this demand, this paper proposes a graded Mxene-doped liquid metal (LM) method to achieve a stable solid-liquid composite interconnect (SLCI) between the rigid chip and stretchable interconnect lines. To overcome the surface tension of LM, a high-conductive Mxene is doped for the balance between adhesion and liquidity of LM. And the high-concentration doping could prevent the contact failure with chip pins, while the low-concentration doping tends to maintain the stretchability. Based on this dosage-graded interface structure, the solid light-emitting diode (LED) and other devices integrated into the stretchable hybrid electronic system could achieve an excellent conductivity insensitive to the exerted tensile strain. In addition, the hybrid electronic system is demonstrated for skin-mounted and tire-mounted temperature-test applications under the tensile strain up to 100%. This Mxene-doped LM method aims to obtain a robust interface between rigid components and flexible interconnects by attenuating the inherent Young's modulus mismatch between rigid and flexible systems and makes it a promising candidate for effective interconnection between solid electronics and soft electronics.

Programming Strategy Optimization of RRAM Fabricated by 28 nm Standard CMOS Process

The switching characteristics of HfOx-based resistive switching random access memory (RRAM) fabricated on front-end of 28 nm standard CMOS process are investigated. The integration of RRAM in the front-end of the CMOS process would minimize the influence of parasitic parameters caused by interconnection line and interlayer oxide on the one transistor one RRAM (1T1R) cells. By adopting pulse program-verify measurement for cycling test, we observe two nonideal phenomena in the commercialized RRAM devices for the first time: 1) low resistance state (LRS) current periodically decays exponentially accompanied by incremental SET pulse number and then increases abruptly when the cycle reaches a certain level and 2) high resistance state (HRS) current fluctuated dramatically during RESET operation. The current fluctuation is mainly due to the generation of new oxygen vacancies (Vos) near the bottom electrode and gap region by electrons trapping/detrapping. By adopting efficient pulse amplitude modulation, the optimized programming strategy has greatly reduced the switching instability and improved the endurance of the devices. Mechanisms of the instability and the optimization strategy are explained by a modified trap-assisted tunneling (TAT) model based on the generation and redistribution of Vos during cycling operations.

Industrial applications of a modular software architecture for line-less assembly systems based on interoperable digital twins

In manufacturing, rising demands for customized products have led to increased product variance and shortened product life cycles. In assembly lines, an increased variant diversity impedes the product flow. As a result, the utilization of assembly resources decreases, and production costs grow. An approach to increase the flexibility and adaptability of the assembly system is the implementation of the concept of line-less assembly. In the first step, the assembly line is dissolved. Then, stations are reallocated and linked by automated guided vehicles resulting in a loosely coupled layout, for example, a parallelization and interconnection of multiple lines or a matrix layout. A key requirement for the successful operation and control of a line-less assembly system is the collection and correct interpretation of data. To fully exploit the flexibility and adaptability of the concept of line-less assembly, a software architecture for planning and control must base on an information model allowing the fast integration of all shop floor assets and other data resources. Therefore, a modular data model with standardized interfaces for interoperable data exchange like a digital twin is needed. The aim of this paper is the development and implementation of a software architecture for planning and control of a line-less assembly system. Moreover, the architecture should integrate an interoperable digital twin of the physical system. To satisfy the criteria of interoperability and fast deployment, the digital twins are evolved following the methodology of a digital twin pipeline. Furthermore, a physical demonstrator serves as a testbed for the developed software architecture and digital twins. On the level of production planning and control, relevant industrial applications are identified and implemented in the form of use cases to show the functionality of the line-less assembly system as cyber-physical production system.

Enhanced Control Designs to Abate Frequency Oscillations in Compensated Power System

The interconnection of transmission, distribution, and generation lines has established a structure for the power system that is intricate. Uncertainties in the active power flow are caused by changes in load and a growing dependence on renewable energy sources. The study presented in this paper employs several controlling strategies to reduce frequency variations in series-compensated two-area power systems. Future power systems will require the incorporation of flexible AC transmission system (FACTS) devices, since the necessity for compensation in the power system is unavoidable. Therefore, a static synchronous series compensator (SSSC) is installed in both areas of our study to make it realistic and futuristic. This makes it easier to comprehend how series compensation works in a load–frequency model. With the integration of electrical vehicles (EVs) and solar photovoltaic (PV) systems, several control strategies are presented to reduce the frequency oscillations in this power system. Particle swarm optimization (PSO) is used to obtain the best PI control. To improve results, this work also covers the design of fuzzy logic control. In addition, the adoption of neural network control architecture is proposed for even better outcomes. The outcomes clearly show how well the proposed control techniques succeeded.

Crosstalk analysis of dielectric inserted side contact multilayer graphene nanoribbon interconnects for ternary logic system using unconditionally stable FDTD model

In the present work, for examining the performance of dielectric inserted side contact multilayer graphene nano ribbon (DSMLGNR), a novel Unconditionally Stable Finite-Difference Time-Domain (USFDTD) technique is proposed. This technique overcomes the constraint of courant stability condition prevailing in FDTD technique. The proposed mathematical model is highly time efficient and accurately analyzes the crosstalk effects induced among the coupled interconnect lines. The robustness of the USFDTD technique is verified by determining various performance metrics and justifying it with FDTD technique and HSPICE simulations. The obtained results are in accordance with HSPICE and the average percentage error is less than 1%. For performing the transient analysis, USFDTD model consumes 25% lesser time compared to FDTD technique. Furthermore, accuracy of the proposed model is validated by using Feature Selective Validation (FSV) tool.

Modified FOPID Controller for Frequency Regulation of a Hybrid Interconnected System of Conventional and Renewable Energy Sources

In this article, a fractional-order proportional-integral-differential (FOPID) controller and its modified structure, called a MFOPID controller, are presented. To guarantee optimal system performance, the gains of the proposed FOPID and MFOPID controllers are well-tuned, employing the Jellyfish Search Optimizer (JSO), a novel and highly effective bioinspired metaheuristic approach. The proposed controllers are assessed in a hybrid system with two domains, where each domain contains a hybrid of conventional (gas, reheat, and hydro) and renewable generation sources (solar and wind). For a more realistic analysis, the presented system model includes practical limitations with nonlinear characteristics, such as governor dead zone/band (GDZ/GDB), boiler dynamics, generation rate limitation/constraint (GRL/GRC), system uncertainties, communication time delay (CTD), and load changes. The suggested methodology outperforms some newly developed heuristic techniques, including fitness-dependent optimizer (FDO), sine-cosine algorithm (SCA), and firefly algorithm (FA), for the interconnected power system (PS) of two regions with multiple generating units. Furthermore, the proposed MFOPID controller is compared with JSO-tuned PID/FOPID and PI controllers to ascertain its superiority. The results signify that the presented control method and its parametric optimization significantly outperforms the other control strategies with respect to minimum undershoot and peak overshoot, settling times, and ITSE in the system’s dynamic response. The sensitivity analysis outcomes imply that the proposed JSO-MFOPID control method is very reliable and can effectively stabilize the load frequency and interconnection line in a multi-area network with interconnected PS.

Enhanced IDA-PBC Applied to a Three-Phase PWM Rectifier for Stable Interfacing Between AC and DC Microgrids Embedded in More Electrical Aircraft

To cope with future goal of efficiency, next generation of more electrical aircraft is likely to embed reconfigurable microgrid for the primary electrical distribution. The stability analysis of such time-varying structure is challenging. Conventional linear and nonlinear approaches failed to produce proper answers from a practical point of view. Under conditions, passivity property of each equipment is sufficient to ensure stability of the overall microgrid. But with improper passivity-based control (PBC) design, the passivity property may not be propagated. The main contribution of this article is to propose a modified IDA-PBC procedure that will ensure the passivity properties of the system regarding its electrical inputs and outputs involved in the interconnection. Thus, for electrical microgrids resulting from the interconnection of controllable equipment, input/output filters, and electrical lines, if all the equipment embed the proposed control, the whole microgrid have passive properties and the global stability of the system is ensured. Moreover, this article will also present how to achieve the proposed control with high transient and robust performances thanks to nonlinear parameters’ estimator preserving the passivity proper. Experimental validation of the proposed control in representative electrical conditions is provided.

Coordination of Neighboring Active Distribution Networks Under Electricity Price Uncertainty Using Distributed Robust Bi-Level Programming

Distributed energy resources transform the passive distribution networks into active distribution networks (ADNs). Coordinating the dispatch actions of distributed resources has been studies in the literature, both within an ADN and between an ADN and the transmission system. However, the direct coordination between ADNs interconnected via a physical tie line is a topic boldly under-discussed, despite its practical relevance. In this paper, we consider the problem of coordinating the dispatch actions, including the energy exchange, of two interconnected ADNs, each one integrated with flexible loads (managed by demand response aggregators), energy storage systems, and microturbines (MTs). The bilateral energy trading enables the neighboring ADNs to benefit from the difference in locational marginal prices. The coordination problem is formulated as a robust bi-level program under price uncertainty. At the upper level, the total cost of the ADNs is minimized subject to the uncertainty of electricity market prices and technical constraints of the networks and the resources. At the lower level, the DR aggregators present at each ADN selfishly minimize their own cost. Moreover, the worst case realization of wholesale electricity market prices is considered. The problem is linearized using the Karush–Kuhn–Tucker (KKT) conditions and decomposed using the alternating direction method of multipliers (ADMM). Simulation results verify the convergence behavior of the proposed method and quantify the value of DSO-DSO coordination in the presence of an interconnecting line between the ADNs.

Investigation of novel leveler Rhodamine B on copper superconformal electrodeposition of microvias by theoretical and experimental studies

Achieving void-defect copper filling by electrodeposition on microvias is essentially important. Rhodamine B (RhB) is of excellent suppressing ability based on electrochemical analysis. Convection-dependent adsorption analysis demonstrates that 100 mg/L was the optimum value to achieve bottom-up growth. The interaction among sodium 3,3′-dithiodipropane sulfonate, polyethylene glycol, and RhB was investigated and competition adsorption between RhB and SPS is observed. Meanwhile, copper electrodeposition obeys 3D diffusion-controlled progressive nucleation process at low potential but obeys 3D diffusion-controlled instantaneous nucleation process at high overpotential. Density functional theory and in situ Raman spectra were used to study the adsorption behavior of RhB. The calculated results indicates that RhB can effectively increase the energy barrier during copper electrodeposition. The surface morphology is improved and surface roughness is lowered with proper RhB concentration. The influence of RhB on orientation and grain size was analyzed and proper RhB (100 mg/L) is conducive to the formation of Cu (111) surface and lowering the grain size. Besides, the introduction of RhB can improve the wettability, which is conducive to the bottom-up growth. The electroplating process is optimized and void-defect copper interconnect line with high quality is obtained.

Sequential Design of Decentralized Robust Controllers for Strongly Interconnected Inverter-Based Distributed Generation Systems: A Comparative Study versus Independent Design

Internal oscillations among multiple generation systems in low-voltage stand-alone nanogrids and small-scale microgrids can cause instability in the entire generation system. This issue becomes worse when the coupling strength between the generation systems increases, which is a result of a shorter distance between them and a smaller reactance to resistance ratio. Previous approaches, which were based on the independent control design and considered the coupling effect as disturbances, may fail to tackle this issue when the two generation systems become strongly coupled. Therefore, in this paper a novel method is proposed to handle this coupling effect by designing robust decentralized controllers in a sequential manner to address the problem of voltage and frequency control in a nanogrid. This proposed sequential design is a general technique that is applicable to multiple inverter-based generation systems in a nanogrid or small-scale microgrid. For the ease of demonstration, in this paper the case of two interconnected inverters with LC output filters is studied. Two robust decentralized controllers are designed for the two inverter systems by using the μ-synthesis technique. The sequential design takes into account the interconnection line between the two inverters. Moreover, the controllers are designed to be robust against all the parameter variations in the system including the LC filter and interconnection line parameters. The simulation results demonstrate the superior performance of the proposed controller over the independently-designed controllers for the case of two generation systems that are highly coupled due to the short distance between them. Moreover, the proposed controller is shown to be robust against the LC filter and interconnection line parameter uncertainties as compared to the sequentially-designed linear quadratic Gaussian controllers.

Doped Ru to enable next generation barrier-less interconnect

An effective method for the formation of a Zn-doped Ru liner is demonstrated that realizes a self-forming barrier to achieve low resistivity interconnects for future back-end of line interconnect nodes. The “Ru–Zn” exhibits significantly improved adhesion to the dielectric and better electrochemical nucleation as compared to those of pristine Ru. In addition, time-dependent dielectric breakdown (TDDB) measurements indicate the inhibition of Cu ions drifting into the dielectric that precedes the TDDB failure. Complementary analysis using x-ray absorption spectroscopy, transmission electron microscope, and energy dispersive spectroscope suggests that the “Ru–Zn” forms an interfacial Zn–Si–O compound, and Zn, being more electronegative than Cu, protects the latter from oxidation. Calculation using density function theory also indicates that the Zn–Si–O compound adopts an intercalated structure at the interface of Ru/dielectric in which Zn occupies the interstitial sites within the Si–O lattice. We propose a twofold mechanism for improved TDDB performance: (1) the intercalated Zn atoms effectively block the diffusion of Cu ions through the dielectric and (2) Zn provides the cathodic protection of Cu that prevents the generation of mobile Cu ions that accelerate the TDDB.

An Improved Thru-Line De-Embedding Technique up to 80 GHz

With the rapid increase of high-speed communications, the frequency range of integrated circuits enters the field of millimeter wave, and the size of devices has become smaller and smaller. In the measurement of microwave devices, the probe cannot contact the device directly. The actual device under test (DUT) is surrounded by metal traces called leads, which provide the interface between the probing pads on the wafer and the DUT itself. The probes are pressed on the pads at both ends of the DUT. The parasitic effect of pads and transmission lines is significant at high frequency. The established technique such as Short-Open-Load-Thru (SOLT) and Line-Reflect-Reflect-Match (LRRM) move the reference plane up to the tip of the probes by means of Cascade Microtech impedance standard substrate (ISS). To obtain accurate parameters of DUT, a deembedding method must be implemented to eliminate the influence of pads and interconnect transmission lines.

Self-assembled monolayers on porous low-k dielectrics by decyltrimethoxysilane vapor treatment: A perspective from electrical characteristics and time-dependence-dielectric-breakdown reliability

Self-assembled monolayer (SAM) is an attractive technology for back-end-of–line interconnects of integrated circuits for advanced technological nodes. In this study, SAMs were formed on the porous low-k films by decyltrimethoxysilane (DTMOS) in vapor phase at different temperatures. The effects of the formation SAMs on the electrical characteristics and reliability of the porous low-k films were characterized. With DTMOS vapor treatment at 50°C∼100°C, SAMs were formed onto the porous low-k films, thus enhancing the dielectric breakdown field, failure time, and Cu barrier capacity. Additionally, DTMOS vapor treatment at higher temperatures resulted in larger enhancement and more thermal stability. The formation SAMs was demonstrated to effectively repair the damaged porous low-k film, thus reducing the dielectric constant; although, the bulk dielectric constant was higher than that of the pristine film. To sum up, this study provided a promising SAMs processing derived from DTMOS vapor phase, for ensuring better integrity for the porous low-k films in the advanced technological nodes.