[paper] SPICE Modeling of Cycle-to-Cycle Variability in RRAM Devices

E.Salvador^a, M.B.Gonzalez^b, F.Campabadal^b, J.Martin-Martinez^a, R.Rodriguez^a, E.Miranda^a

SPICE Modeling of Cycle-to-Cycle Variability in RRAM Devices

Solid-State Electronics; In Press, Journal Pre-proof

Available online 29 May 2021, 108040

DOI: 10.1016/j.sse.2021.108040

a) Departament d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Valles, Spain
b) Institut de Microelectrònica de Barcelona, IMB-CNM, CSIC, 08193 Cerdanyola del Valles, Spain

Abstract: In this work, we investigated how to include uncorrelated cycle-to-cycle (C2C) variability in the LTSpice quasi-static memdiode model for RRAM devices. Variability in the I-V curves is first addressed through an in-depth study of the experimental data using the FITDISTRPLUS package for the R language. This provides a first approximation to the identification of the most suitable model parameter distributions. Next, the selected candidate distributions are incorporated into the model script and used for carrying out Monte Carlo simulations. Finally, the experimental and simulated observables (set and reset currents, transition voltages, etc.) are statistically compared and the model estimands recalculated if it is necessary. Here, we put special emphasis on describing the main difficulties behind this seemingly simple procedure.

Figure 4. Comparison of experimental and simulated parameter distributions: 

a) IHRS, b) VT, c) ILRS, and d) VR.

Acknowledgements: This work was supported by the Spanish Ministry of Science, Innovation and Universities through projects TEC2017-84321-C4-1-R, TEC2017-84321-C4-4-R, and PID2019-103869RB-C32.

[paper] NESS Open-Source TCAD Environment

Cristina Medina-Bailon, Tapas Dutta, Fikru Adamu-Lema, Ali Rezaei, Daniel Nagy,

Vihar P. Georgiev, and Asen Asenov

Nano-Electronic Simulation Software (NESS): 

A Novel Open-Source TCAD Simulation Environment

Journal of Microelectronic Manufacturing

Vol 3 (4) : 20030407 2020

DOI:  10.33079/jomm.20030407

Abstract: This paper presents the latest status of the open source advanced TCAD simulator called Nano-Electronic Simulation Software (NESS) which is currently under development at the Device Modeling Group of the University of Glasgow. NESS is designed with the main aim to provide an open, flexible, and easy to use simulation environment where users are able not only to perform numerical simulations but also to develop and implement new simulation methods and models. Currently, NESS is organized into two main components: the structure generator and a collection of different numerical solvers; which are linked to supporting components such as an effective mass extractor and materials database. This paper gives a brief overview of each of the components by describing their main capabilities, structure, and theory behind each one of them. Moreover, to illustrate the capabilities of each component, here we have given examples considering various device structures, architectures, materials, etc. at multiple simulation conditions. We expect that NESS will prove to be a great tool for both conventional as well as exploratory device research programs and projects.

Fig: Randomly generated atomistic device considering random discrete dopants (RDD) and metal gate granularity (MGG) in the NESS simulation domain

Acknowledgments: This project was initiated by the European Union Horizon 2020 research and innovation programme under grant agreement No. 688101 SUPERAID7 and has received further funding from EPSRC UKRI Innovation Fellowship scheme under grant agreement No. EP/S001131/1 (QSEE), No. EP/P009972/1 (QUANTDEVMOD) and No. EP/S000259/1 (Variability PDK for design based research on FPGA/neuro computing); and from H2020-FETOPEN-2019 scheme under grant agreement No.862539-Electromed-FET OPEN. The coauthors would like to thank Dr. Carrillo-Nuñez, Dr. Lee, Dr. Berrada, Dr. Badami, and Dr. Duan for their former contribution to NESS; as well as Dr. Donetti for the possibility of using the 1DMC tool. 

[paper] oTFT Charge-Based Variability Model

Aristeidis Nikolaou, Ghader Darbandy, Jakob Leise, Jakob Pruefer, James W. Borchert, Michael Geiger, Hagen Klauk, Benjamin Iñiguez, Fellow, IEEE,

and Alexander Kloes, Senior Member, IEEE

Charge-Based Model for the Drain-Current Variability in Organic Thin-Film Transistors 

Due to Carrier-Number and CorrelatedMobility Fluctuation

in IEEE TED (early access), DOI: 10.1109/TED.2020.3018694.

Abstract: In this study, a consistent analytical chargebased model for the bias-dependent variability of the drain current of organic thin-film transistors is presented. The proposed model combines both charge-carrier-numberfluctuation effects and correlated-mobility-fluctuation effects to predict the drain-current variation and is verified using experimental data acquired from a statistical population of organic transistors with various channel dimensions, fabricated on flexible polymeric substrates in the coplanar or the staggered device architecture.

Fig: a) Cross section of the organic TFTs fabricated in the inverted coplanar (bottom-gate, bottom-contact) architecture. b) Transistor channel divided into a noisy element between positions x and x + δx and two noiseless transistors of channel lengths x and L − x, respectively. c) Small-signal representation.

Acknowledgment: This work was supported in part by the German Federal Ministry of Education and Research “SOMOFLEX” under Grant 13FH015IX6 and in part by the German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom). The authors would like to thank AdMOS GmbH for support.

[paper] NESS

Nano-electronic Simulation Software (NESS): 

a flexible nano-device simulation platform

Salim Berrada, Hamilton Carrillo-Nunez, Jaehyun Lee, Cristina Medina-Bailon, Tapas Dutta, Oves Badami, Fikru Adamu-Lema, Vasanthan Thirunavukkarasu, Vihar Georgiev and Asen Asenov 

Journal of Computational Electronics (2020)

DOI: 10.1007/s10825-020-01519-0

Abstract: The aim of this paper is to present a flexible and open-source multi-scale simulation software which has been developed by the Device Modelling Group at the University of Glasgow to study the charge transport in contemporary ultra-scaled Nano-CMOS devices. The name of this new simulation environment is Nano-electronic Simulation Software (NESS). Overall NESS is designed to be flexible, easy to use and extendable. Its main two modules are the structure generator and the numerical solvers module. The structure generator creates the geometry of the devices, defines the materials in each region of the simulation domain and includes eventually sources of statistical variability. The charge transport models and corresponding equations are implemented within the numerical solvers module and solved self-consistently with Poisson equation. Currently, NESS contains a drift–diffusion, Kubo–Greenwood, and non-equilibrium Green’s function (NEGF) solvers. The NEGF solver is the most important transport solver in the current version of NESS. Therefore, this paper is primarily focused on the description of the NEGF methodology and theory. It also provides comparison with the rest of the transport solvers implemented in NESS. The NEGF module in NESS can solve transport problems in the ballistic limit or including electron–phonon scattering. It also contains the Flietner model to compute the band-to-band tunneling current in heterostructures with a direct band gap. Both the structure generator and solvers are linked in NESS to supporting modules such as effective mass extractor and materials database. Simulation results are outputted in text or vtk format in order to be easily visualized and analyzed using 2D and 3D plots. The ultimate goal is for NESS to become open-source, flexible and easy to use TCAD simulation environment which can be used by researchers in both academia and industry and will facilitate collaborative software development.

FIG: Flowchart of NESS detailing its modular structure

NESS will be released in the summer of 2020 as an open-source software which makes it very interesting for both academia and industry in helping to address the challenges subsequent to the further down-scaling of CMOS components.

Acknowledgements: This work was supported by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 688101 SUPERAID7. Also, this project has received funding from EPSRC UKRI under Grant Agreements No. EP/S001131/1 (QSEE) and No. EP/P009972/1 (QUANTDEVMOD).

[paper] A Compact Model for the Statistics of the Low-Frequency Noise of MOSFETs With Laterally Uniform Doping

M. Banaszeski da Silva, H. P. Tuinhout, A. Zegers-van Duijnhoven, G. I. Wirth and A. J. Scholten

"A Compact Model for the Statistics of the Low-Frequency Noise of MOSFETs With Laterally Uniform Doping" 

in IEEE TED, vol. 64, no. 8, pp. 3331-3336, Aug. 2017.
doi: 10.1109/TED.2017.2713301

Abstract: In this paper, we develop a compact physics-based statistical model for random telegraph noise-related low-frequency noise in bulk MOSFETS with laterally uniform doping. The proposed model is suited for modern compact device models, such as PSP, BSIM, and EKV. With our proposed model, one can calculate the expected value and the variability of the noise as a function of bias and device parameters. We validate the model through numerous experimental results from different CMOS nodes, down to 40 nm [read more...]

[paper] A Compact Model for the Statistics of the Low-Frequency Noise of MOSFETs With Laterally Uniform Doping

A Compact Model for the Statistics of the Low-Frequency Noise of MOSFETs With Laterally Uniform Doping

M. Banaszeski da Silva; H. P. Tuinhout; A. Zegers-van Duijnhoven; G. I. Wirth; A. J. Scholten;

in IEEE Transactions on Electron Devices, vol.PP, no.99, pp.1-6
doi: 10.1109/TED.2017.2713301

Abstract: In this paper, we develop a compact physics-based statistical model for random telegraph noise-related low-frequency noise in bulk MOSFETS with laterally uniform doping. The proposed model is suited for modern compact device models, such as PSP, BSIM, and EKV. With our proposed model, one can calculate the expected value and the variability of the noise as a function of bias and device parameters. We validate the model through numerous experimental results from different CMOS nodes, down to 40 nm. [read more...]

[ESSDERC Paper] Compact model for variability of low frequency noise due to number fluctuation effect

Compact model for variability of low frequency noise due to number fluctuation effect

N. Mavredakis and M. Bucher

2016 46th European Solid-State Device Research Conference (ESSDERC)

Lausanne, Switzerland, 2016, pp. 464-467

doi:10.1109/ESSDERC.2016.7599686

Abstract: Variability of low frequency noise (LFN) in MOSFETs is both geometry- and bias-dependent. RTS noise prevails in smaller devices where noise deviation is mostly area-dominated. As device dimensions increase, operating conditions determine noise variability maximizing it in weak inversion and increasing it with drain voltage. This dependence is shown to be directly related with fundamental carrier number fluctuation effect. A new bias- and area-dependent, physics-based, compact model for 1/f noise variability is proposed. The model exploits the log-normal behavior of LFN. The model is shown to give consistent results for average noise, variance, and standard deviation, covering bias-dependence and scaling over a large range of geometry.

Keywords: compact models, Low-frequency noise, MOSFET, Reactive power, Semiconductor device modeling, Shape, Standards, MOSFET, low frequency noise, noise variability

URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7599686&isnumber=7598672