Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551705
Daniel Valencia, Kuang-Chung Wang, Yuanchen Chu, Gerhard Klimeck, M. Povolotskyi
As interconnects become smaller, their conductivity increases along with the parasitic effects in MOSFET technologies [1] Therefore, investigating how to model the scattering effects on the nanoscale is important to determine how to engineer interconnects toreduce those parasitic effects. In this work, a fully atomistic method is studied to model the electronic transport properties of copper thin films. For this purpose, a tight binding basis previously benchmarked against first principles calculations [2] is used todescribe surface roughness and grain boundary effects on comparablepper thin films with a thickness comparable to the values suggested by ITRS roadmap [3]. In contrast with traditional models, the results show that the tight binding method can quantify those scattering effects at low temperature without fitting any experimental parameters [4], [5].
{"title":"Surface and Grain-boundary Effects in Copper interconnects Thin Films Modeling with an Atomistic Basis","authors":"Daniel Valencia, Kuang-Chung Wang, Yuanchen Chu, Gerhard Klimeck, M. Povolotskyi","doi":"10.1109/SISPAD.2018.8551705","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551705","url":null,"abstract":"As interconnects become smaller, their conductivity increases along with the parasitic effects in MOSFET technologies [1] Therefore, investigating how to model the scattering effects on the nanoscale is important to determine how to engineer interconnects toreduce those parasitic effects. In this work, a fully atomistic method is studied to model the electronic transport properties of copper thin films. For this purpose, a tight binding basis previously benchmarked against first principles calculations [2] is used todescribe surface roughness and grain boundary effects on comparablepper thin films with a thickness comparable to the values suggested by ITRS roadmap [3]. In contrast with traditional models, the results show that the tight binding method can quantify those scattering effects at low temperature without fitting any experimental parameters [4], [5].","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"1971 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130044059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551694
F. Ducry, K. Portner, S. Andermatt, M. Luisier
Conductive bridging random access memories (CBRAM) are emerging non-volatile data storage devices whose switching mechanisms are not fully understood. Here, we present a modelling framework based on ab-initio simulations to investigate CBRAM cells. It combines density-functional theory and the Non-equilibrium Greens Function formalism. Realistic metallic filaments connecting two electrodes are constructed and their ballistic transport characteristics studied. For a given filament the type of counter electrode material has little influence on the magnitude of the ON-state current, but affects its spatial distribution. The conductance mainly depends on the material of the active electrode and the shape of the thinnest part of the filament.
{"title":"Investigation of the Electrode Materials in Conductive Bridging RAM from First-Principle","authors":"F. Ducry, K. Portner, S. Andermatt, M. Luisier","doi":"10.1109/SISPAD.2018.8551694","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551694","url":null,"abstract":"Conductive bridging random access memories (CBRAM) are emerging non-volatile data storage devices whose switching mechanisms are not fully understood. Here, we present a modelling framework based on ab-initio simulations to investigate CBRAM cells. It combines density-functional theory and the Non-equilibrium Greens Function formalism. Realistic metallic filaments connecting two electrodes are constructed and their ballistic transport characteristics studied. For a given filament the type of counter electrode material has little influence on the magnitude of the ON-state current, but affects its spatial distribution. The conductance mainly depends on the material of the active electrode and the shape of the thinnest part of the filament.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"184 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116201413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551742
K. Sonoda, E. Tsukuda, S. Tsuda, Tomohiro Hayashi, Y. Akiyama, Y. Yamaguchi, T. Yamashita
The effect of field enhancement at Fin corners on program characteristics of FinFET Split-gate metal oxide nitride oxide silicon (SG-MONOS) is analyzed. The program characteristics using source-side injection (SSI) are found to be insensitive to the variation of the curvature radius at Fin corners, which shows the robustness of FinFET SG-MONOS to Fin shape variation inthe fabrication process.
{"title":"Analysis of the Effect of Field Enhancement at Fin Corners on Program Characteristics of FinFET Split-Gate MONOS","authors":"K. Sonoda, E. Tsukuda, S. Tsuda, Tomohiro Hayashi, Y. Akiyama, Y. Yamaguchi, T. Yamashita","doi":"10.1109/SISPAD.2018.8551742","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551742","url":null,"abstract":"The effect of field enhancement at Fin corners on program characteristics of FinFET Split-gate metal oxide nitride oxide silicon (SG-MONOS) is analyzed. The program characteristics using source-side injection (SSI) are found to be insensitive to the variation of the curvature radius at Fin corners, which shows the robustness of FinFET SG-MONOS to Fin shape variation inthe fabrication process.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116546743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551718
M. Duan, B. Cheng, C. Bailón, F. Adamu-Lema, P. Asenov, C. Millar, P. Pfaeffli, A. Asenov
Z2FET is a promising integrated DRAM device to replace the traditional 1 transistor 1 capacitor DRAM [1–4]. Memory products always require minimum cell size, high density and large volume memory arrays in the limited chip real estate. However, the downscaling of Z2FET dimensions leads to severe variability issues. A novel simulation methodology has been already proposed [5] to investigate the initial Z2FET Statistical Variability (SV), but the aging induced Time Dependent Variability (TDV) has never been considered.
{"title":"Modelling on Aging Induced Time Dependent Variability of Z2FET for Memory Applications","authors":"M. Duan, B. Cheng, C. Bailón, F. Adamu-Lema, P. Asenov, C. Millar, P. Pfaeffli, A. Asenov","doi":"10.1109/SISPAD.2018.8551718","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551718","url":null,"abstract":"Z2FET is a promising integrated DRAM device to replace the traditional 1 transistor 1 capacitor DRAM [1–4]. Memory products always require minimum cell size, high density and large volume memory arrays in the limited chip real estate. However, the downscaling of Z2FET dimensions leads to severe variability issues. A novel simulation methodology has been already proposed [5] to investigate the initial Z2FET Statistical Variability (SV), but the aging induced Time Dependent Variability (TDV) has never been considered.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131161032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551730
M. L. Van de Put, A. Laturia, M. Fischetti, W. Vandenberghe
We present a method to simulate ballistic quantum transport in one-dimensional nanostructures, such as extremely scaled transistors, with a channel of nanowires or nanoribbons. In contrast to most popular approaches, we develop our method employing an accurate plane-wave basis at the atomic scale while retaining the numerical efficiency of a localized (tight-binding) basis at larger scales. At the core of our method is a finite-element expansion, where the finite element basis is enriched by a set of Bloch waves at high-symmetry points in the Brillouin zone of the crystal. We demonstrate the accuracy and efficiency of our method with the self-consistent simulation of ballistic transport in graphene nanoribbon FETs.
{"title":"Efficient Modeling of Electron Transport with Plane Waves","authors":"M. L. Van de Put, A. Laturia, M. Fischetti, W. Vandenberghe","doi":"10.1109/SISPAD.2018.8551730","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551730","url":null,"abstract":"We present a method to simulate ballistic quantum transport in one-dimensional nanostructures, such as extremely scaled transistors, with a channel of nanowires or nanoribbons. In contrast to most popular approaches, we develop our method employing an accurate plane-wave basis at the atomic scale while retaining the numerical efficiency of a localized (tight-binding) basis at larger scales. At the core of our method is a finite-element expansion, where the finite element basis is enriched by a set of Bloch waves at high-symmetry points in the Brillouin zone of the crystal. We demonstrate the accuracy and efficiency of our method with the self-consistent simulation of ballistic transport in graphene nanoribbon FETs.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127770914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551711
M. Luisier, F. Ducry, M. Hossein, Bani-Hashemian, S. Brück, M. Calderara, O. Schenk
Numerical algorithms dedicated to large-scale quantum transport problems from first-principles are presented in this paper. They can be decomposed into three main categories: (i) the calculation of the open boundary conditions that connect the simulation domain and its environment, (ii) the solution of the resulting Schrödinger equation in the ballistic limit of transport, and (iii) the extension of this case to situations involving scattering, e.g. electron-phonon interactions. It will be shown that ab-initio device simulations require algorithms specifically developed for that purpose and that graphics processing units (GPUs) can bring significant speed ups as compared to solvers based on CPUs only. As an illustration, the computational times coming from the investigation of a realistic conductive bridging random access memory cell will be reported.
{"title":"Advanced Algorithms for Ab-initio Device Simulations","authors":"M. Luisier, F. Ducry, M. Hossein, Bani-Hashemian, S. Brück, M. Calderara, O. Schenk","doi":"10.1109/SISPAD.2018.8551711","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551711","url":null,"abstract":"Numerical algorithms dedicated to large-scale quantum transport problems from first-principles are presented in this paper. They can be decomposed into three main categories: (i) the calculation of the open boundary conditions that connect the simulation domain and its environment, (ii) the solution of the resulting Schrödinger equation in the ballistic limit of transport, and (iii) the extension of this case to situations involving scattering, e.g. electron-phonon interactions. It will be shown that ab-initio device simulations require algorithms specifically developed for that purpose and that graphics processing units (GPUs) can bring significant speed ups as compared to solvers based on CPUs only. As an illustration, the computational times coming from the investigation of a realistic conductive bridging random access memory cell will be reported.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"29 44","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132707454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551714
Kuang-Chung Wang, Yuanchen Chu, Daniel Valencia, J. Geng, J. Charles, Prasad Sarangapani, T. Kubis
The non-equilibrium Green function (NEGF) method is capable of nanodevice performance predictions including coherent and incoherent effects. To treat incoherent scattering, carrier generation and recombination is computationally very expensive. In this work, the numerically efficient Buttiker-probe model is expanded to cover recombination and generation effects in addition to various incoherent scattering processes. The capability of the new method to predict nanodevices is exemplified with quantum well III-N light-emitting diodes and anti-ambipolar 2D material hetero junctions.
{"title":"Nonequilibrium Green’s function method: Büttiker probes for carrier generation and recombination","authors":"Kuang-Chung Wang, Yuanchen Chu, Daniel Valencia, J. Geng, J. Charles, Prasad Sarangapani, T. Kubis","doi":"10.1109/SISPAD.2018.8551714","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551714","url":null,"abstract":"The non-equilibrium Green function (NEGF) method is capable of nanodevice performance predictions including coherent and incoherent effects. To treat incoherent scattering, carrier generation and recombination is computationally very expensive. In this work, the numerically efficient Buttiker-probe model is expanded to cover recombination and generation effects in addition to various incoherent scattering processes. The capability of the new method to predict nanodevices is exemplified with quantum well III-N light-emitting diodes and anti-ambipolar 2D material hetero junctions.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"235 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133153309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551626
L. P. Tatum, Madeline Sciullo, M. Law
In this work, we present a 2-Valley energy band model of electron transport that delivers more accurate solutions compared with the Farahmand model but with improved convergence and a faster solution time for very high electric fields. This was achieved by implementing the Fermi-Dirac integral distribution as a substitution for the Boltzmann exponential, electron carrier temperature due to heat generation and conduction in the semiconductor lattice, and additional electron concentration modeling for a second conduction energy band minima. The model was primarily tuned by varying the electron temperature relaxation time constant. It was tested using a GaN-based High Electron Mobility Transistor using the Finite-Element Quasi Fermi method.
{"title":"Simulation of Hot-Electron Effects with Multi-band Semiconductor Devices","authors":"L. P. Tatum, Madeline Sciullo, M. Law","doi":"10.1109/SISPAD.2018.8551626","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551626","url":null,"abstract":"In this work, we present a 2-Valley energy band model of electron transport that delivers more accurate solutions compared with the Farahmand model but with improved convergence and a faster solution time for very high electric fields. This was achieved by implementing the Fermi-Dirac integral distribution as a substitution for the Boltzmann exponential, electron carrier temperature due to heat generation and conduction in the semiconductor lattice, and additional electron concentration modeling for a second conduction energy band minima. The model was primarily tuned by varying the electron temperature relaxation time constant. It was tested using a GaN-based High Electron Mobility Transistor using the Finite-Element Quasi Fermi method.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114646656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551642
N. Prasad, S. Banerjee, L. Register
Interlayer tunnel field effect transistors (ITFETs) make use of resonant tunneling between two layers of two-dimensional semiconductors to create a negative differential resistance. A narrow resonance allows for lowering the operating voltages in potential circuit applications. The use of multiple tunnel barriers is investigated as a means to obtain a narrow resonance, as the device dimensions are scaled down. For specificity, we analyze a bilayer graphene-based ITFET system.
{"title":"Enhancement of Resonance by the Use of Multiple Tunnel Barriers in Bilayer Graphene-Based Interlayer Tunnel Field Effect Transistors","authors":"N. Prasad, S. Banerjee, L. Register","doi":"10.1109/SISPAD.2018.8551642","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551642","url":null,"abstract":"Interlayer tunnel field effect transistors (ITFETs) make use of resonant tunneling between two layers of two-dimensional semiconductors to create a negative differential resistance. A narrow resonance allows for lowering the operating voltages in potential circuit applications. The use of multiple tunnel barriers is investigated as a means to obtain a narrow resonance, as the device dimensions are scaled down. For specificity, we analyze a bilayer graphene-based ITFET system.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"30 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123532581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-09-01DOI: 10.1109/SISPAD.2018.8551663
T. Nishimatsu, A. Payet, Byounghak Lee, Yasuyuki Kayama, Kiyoshi Ishikawa, Alexander Schmidt, I. Jang, Dae Sin Kim
A new dynamical space partitioning method is presented in a parallelized lattice kinetic Monte Carlo (kMC) simulator to overcome the loss of parallel efficiency found in other parallelized kMC simulators. The dynamical partitioning of the simulation cell allows better load balancing through all threads hence reducing time consuming events during the simulation. The new method is evaluated against both hypothetical and real cases. In both cases, minimal differences between serial and parallelized simulations are found. In real cases, other code optimizations may be needed to further improve the parallel efficiency.
{"title":"Dynamical space partitioning for acceleration of parallelized lattice kinetic Monte Carlo simulations","authors":"T. Nishimatsu, A. Payet, Byounghak Lee, Yasuyuki Kayama, Kiyoshi Ishikawa, Alexander Schmidt, I. Jang, Dae Sin Kim","doi":"10.1109/SISPAD.2018.8551663","DOIUrl":"https://doi.org/10.1109/SISPAD.2018.8551663","url":null,"abstract":"A new dynamical space partitioning method is presented in a parallelized lattice kinetic Monte Carlo (kMC) simulator to overcome the loss of parallel efficiency found in other parallelized kMC simulators. The dynamical partitioning of the simulation cell allows better load balancing through all threads hence reducing time consuming events during the simulation. The new method is evaluated against both hypothetical and real cases. In both cases, minimal differences between serial and parallelized simulations are found. In real cases, other code optimizations may be needed to further improve the parallel efficiency.","PeriodicalId":170070,"journal":{"name":"2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123668335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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