Found results matching for:
Author: Javier Díaz Fortuny
Year: Since 2002
Journal Papers
Statistical threshold voltage shifts caused by BTI and HCI at nominal and accelerated conditions
J. Diaz-Fortuny, P. Saraza-Canflanca, R. Rodriguez, J. Martin-Martinez, R. Castro-Lopez, E. Roca, F.V.Fernandez and M. Nafria
Journal Paper · Solid-State Electronics, vol. 185, article 108037, 2021
abstract
doi pdf
In nowadays deeply scaled CMOS technologies, time-zero and time-dependent variability effects have become important concerns for analog and digital circuit design. For instance, transistor parameter shifts caused by Bias Temperature Instability and Hot-Carrier Injection phenomena can lead to progressive deviations of the circuit performance or even to its catastrophic failure. In this scenario, and to understand the effects of these variability sources, an extensive and accurate device characterization under several test conditions has become an unavoidable step towards trustworthy implementing the stochastic reliability models and simulation tools needed to achieve reliable integrated circuits. In this paper, the statistical distributions of threshold voltage shifts in nanometric CMOS transistors will be studied at nominal and accelerated aging conditions. To this end, a versatile transistor array chip and a flexible measurement setup have been used to reduce the required testing time to attainable values.
A robust and automated methodology for the analysis of Time-Dependent Variability at transistor level
P. Saraza-Canflanca, J. Diaz-Fortuny, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, M. Nafria and F.V. Fernandez
Journal Paper · Integration, vol. 72, pp 13-20, 2020
abstract
doi pdf
In the past few years, Time-Dependent Variability has become a subject of growing concern in CMOS technologies. In particular, phenomena such as Bias Temperature Instability, Hot-Carrier Injection and Random Telegraph Noise can largely affect circuit reliability. It becomes therefore imperative to develop reliability-aware design tools to mitigate their impact on circuits. To this end, these phenomena must be first accurately characterized and modeled. And, since all these phenomena reveal a stochastic nature for deeply-scaled integration technologies, they must be characterized massively on devices to extract the probability distribution functions associated to their characteristic parameters. In this work, a complete methodology to characterize these phenomena experimentally, and then extract the necessary parameters to construct a Time-Dependent Variability model, is presented. This model can be used by a reliability simulator.
Flexible Setup for the Measurement of CMOS Time-Dependent Variability with Array-Based Integrated Circuits
J. Diaz-Fortuny, P. Saraza-Canflanca, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, F.V. Fernandez and M. Nafria
Journal Paper · IEEE Transactions on Instrumentation and Measurement, vol. 69, no. 2, pp 853-864, 2020
abstract
doi pdf
This paper presents an innovative and automated measurement setup for the characterization of variability effects in CMOS transistors using array-based integrated circuits (ICs), through which a better understanding of CMOS reliability could be attained. This setup addresses the issues that come with the need for a trustworthy statistical characterization of these effects: testing a very large number of devices accurately but, also, in a timely manner. The setup consists of software and hardware components that provide a user-friendly interface to perform the statistical characterization of CMOS transistors. Five different electrical tests, comprehending time-zero and time-dependent variability effects, can be carried out. Test preparation is, with the described setup, reduced to a few seconds. Moreover, smart parallelization techniques allow reducing the typically time-consuming aging characterization from months to days or even hours. The scope of this paper thus encompasses the methodology and practice of measurement of CMOS time-dependent variability, as well as the development of appropriate measurement systems and components used in efficiently generating and acquiring the necessary electrical signals.
A smart noise- and RTN-removal method for parameter extraction of CMOS aging compact models
J. Diaz-Fortuny, J. Martin-Martinez, R. Rodriguez, R. Castro-Lopez, E. Roca, F.V. Fernandez and M. Nafria
Journal Paper · Solid-State Electronics, vol. 159, pp 99-105, 2019
abstract
doi pdf
In modern nanometer-scale CMOS technologies, time-zero and time-dependent variability (TDV) effects, the latter coming from aging mechanisms like Bias Temperature Instability (BTI), Hot Carrier Injection (HCI) or Random Telegraph Noise (RTN), have re-emerged as a serious threat affecting the performance of analog and digital integrated circuits. Variability induced by the aging phenomena can lead circuits to a progressive malfunction or failure. In order to understand the effects of the mentioned variability sources, a precise and sound statistical characterization and modeling of these effects should be done. Typically, transistor TDV characterization entails long, and typically prohibitive, testing times, as well as huge amounts of data, which are complex to post-process. In order to face these limitations, this work presents a new method to statistically characterize the emission times and threshold voltage shifts (ΔVth) related to oxide defects in nanometer CMOS transistors during aging tests. At the same time, the aging testing methodology significantly reduces testing times by parallelizing the stress. The method identifies the Vth drops associated to oxide trap emissions during BTI and HCI aging recovery traces while removing RTN and background noise contributions, to avoid artifacts during data analysis.
A Versatile CMOS Transistor Array IC for the Statistical Characterization of Time-Zero Variability, RTN, BTI, and HCI
J. Diaz-Fortuny, J. Martin-Martines, R. Rodriguez, R. Castro-Lopez, E. Roca, X. Aragones, E. Barajas, D. Mateo, F.V. Fernandez and M. Nafria
Journal Paper · IEEE Journal of Solid-State Circuits, vol. 54, no. 2, pp 476-488, 2019
abstract
doi pdf
Statistical characterization of CMOS transistor variability phenomena in modern nanometer technologies is key for accurate end-of-life prediction. This paper presents a novel CMOS transistor array chip to statistically characterize the effects of several critical variability sources, such as time-zero variability (TZV), random telegraph noise (RTN), bias temperature instability (BTI), and hot-carrier injection (HCI). The chip integrates 3136 MOS transistors of both pMOS and nMOS types, with eight different sizes. The implemented architecture provides the chip with a high level of versatility, allowing all required tests and attaining the level of accuracy that the characterization of the above-mentioned variability effects requires. Another very important feature of the array is the capability of performing massively parallel aging testing, thus significantly cutting down the time for statistical characterization. The chip has been fabricated in a 1.2-V, 65-nm CMOS technology with a total chip area of 1800 x 1800 µm2.
Conferences
A Smart SRAM-Cell Array for the Experimental Study of Variability Phenomena in CMOS Technologies
P. Saraza-Canflanca, H. Carrasco-Lopez, A. Santana-Andreo, J. Diaz-Fortuny, R. Castro, E. Roca and F.V. Fernandez
Conference · IEEE International Reliability Physics Symposium IRPS 2022
abstract
Time-Dependent Variability phenomena can have a considerable impact on circuit performance, especially for deeply-scaled technologies. To account for this, these phenomena need to be characterized and modelled. Such characterization is often performed at the device level first. Then, the model extracted from such characterization should be validated at the circuit level. To this end, this paper presents a novel chip fabricated in a 65-nm technology that contains an array of 6T SRAM cells. This chip includes some features that make it especially adequate for the characterization of the impact of Time-Dependent Variability phenomena. To demonstrate this adequacy, different tests have been performed to evaluate how Time-Dependent Variability phenomena impact several relevant performance metrics of SRAM cells.
Circuit reliability prediction: challenges and solutions for the device time-dependent variability characterization roadblock
M. Nafria, J. Diaz-Fortuny, P. Saraza-Canflanca, J. Martin-Martinez, E. Roca, R. Castro-Lopez, R. Rodriguez, P. Martin-Lloret, A. Toro-Frias, D. Mateo, E. Barajas, X. Aragones and F.V. Fernandez
Conference · IEEE Latin America Electron Devices Conference LAEDC 2021
abstract
The characterization of the MOSFET Time-Dependent Variability (TDV) can be a showstopper for reliability-aware circuit design in advanced CMOS nodes. In this work, a complete MOSFET characterization flow is presented, in the context of a physics-based TDV compact model, that addresses the main TDV characterization challenges for accurate circuit reliability prediction at design time. The pillars of this approach are described and illustrated through examples.
TiDeVa: A Toolbox for the Automated and Robust Analysis of Time-Dependent Variability at Transistor Level
P. Saraza-Canflanca, J. Diaz-Fortuny, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, M. Nafria and F.V.Fernandez
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2019
abstract
Time-Dependent Variability has attracted
increasing interest in the last years. In particular, phenomena
such as Bias Temperature Instability, Hot Carrier Injection and
Random Telegraph Noise can have a large impact on circuit
reliability, and must be therefore characterized and modeled.
For technologies in the nanometer range, these phenomena
reveal a stochastic behavior and must be characterized in a
massive manner, with enormous amounts of data being
generated in each measurement. In this work, a novel tool with
a user-friendly interface, which allows the robust and fullyautomated
parameter extraction for RTN, BTI and HCI
experiments, is presented.
New method for the automated massive characterization of Bias Temperature Instability in CMOS transistors
P. Saraza-Canflanca, J. Diaz-Fortuny, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, M. Nafria, F.V. Fernandez
Conference · Design Automation and Test in Europe DATE 2019
abstract
Bias Temperature Instability has become a critical issue for circuit reliability. This phenomenon has been found to have a stochastic and discrete nature in nanometerscale CMOS technologies. To account for this random nature, massive experimental characterization is necessary so that the extracted model parameters are accurate enough. However, there is a lack of automated analysis tools for the extraction of the BTI parameters from the extensive amount of generated data in those massive characterization tests. In this paper, a novel algorithm that allows the precise and fully automated parameter extraction from experimental BTI recovery current traces is presented. This algorithm is based on the Maximum Likelihood Estimation principles, and is able to extract, in a robust and exact manner, the threshold voltage shifts and emission times associated to oxide trap emissions during BTI recovery, required to properly model the phenomenon.
A new time efficient methodology for the massive characterization of RTN in CMOS devices
G. Pedreira, J. Martin-Martinez, J. Diaz-Fortuny, P. Saraza-Canflanca, R. Rodriguez, R. Castro-Lopez, E. Roca, F.V. Fernandez and M. Nafria
Conference · IEEE International Reliability Physics Symposium IRPS 2019
abstract
Abstract not avaliable
CMOS characterization and compact modelling for circuit reliability simulation
J. Diaz Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca and F.V. Fernandez
Conference · IEEE Int. Symposium on On-Line Testing and Robust System Design IOLTS 2018
abstract
With nowadays nanometer-CMOS technologies, time-zero and time dependent variability effects (like BTI, CHI, RTN, TDDB, EM, etc) have turned into an even more serious threat to the desired performance of analog and digital integrated circuits. Statistical characterization and modelling of these variability effects entail large testing times, which are typically prohibitive, and huge amounts of data, which are complex to post process. This paper describes novel characterization techniques that overcome these limitations, that is, they are capable of statistically testing nanometer CMOS devices with much shorter completion times. To properly handle the massive amounts of data from characterization, new extraction methods, described in this paper as well, have been developed. With these methods, an accurate variability-aware device model is completed, which can subsequently be used in reliability-aware circuit design methodologies.
Design considerations of an SRAM array for the statistical validation of time-dependent variability models
P. Saraza-Canflanca, D. Malagon, F. Passos, A. Toro, J. Nuñez, J. Diaz-Fortuny, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, M. Nafria and F.V. Fernandez
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2018
abstract
Modeling and characterization of time-dependent variability phenomena as well as the simulation of their impact on circuit operation have attracted considerable efforts. This paper digs into the validation of compact models and simulation tools in the real operation of circuits. One of the most popular blocks, the 6T SRAM, is proposed for this purpose and a test chip containing an SRAM array is designed. The array allows individual access to each SRAM cell, the application of accelerated aging tests as well as the characterization of common performance metrics.
A Model Parameter Extraction Methodology Including Time-dependent Variability for Circuit Reliability Simulation
J. Diaz-Fortuny, P. Saraza-Canflanca, A. Toro-Frias, R. Castro-Lopez, J. Martin-Martinez, E. Roca, R. Rodriguez, F.V. Fernandez and M. Nafria
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2018
abstract
In current CMOS advanced technology nodes, accurate extraction of transistor parameters affected by timedependent variability, like threshold voltage (Vth) and mobility (μ), has become a critical issue for both analog and digital circuit simulation. In this work, a precise VTH0 and U0 BSIM parameters extraction methodology is presented, together with a straightforward IDS to VTH0 shift conversion, to allow the complete study of aging device effects for reliability circuit
Automated massive RTN characterization using a transistor array chip
P. Saraza-Canflanca, J. Diaz-Fortuny, A. Toro-Frias, R. Castro-Lopez, E. Roca, J. Martin-Martinez, R. Rodriguez, M. Nafria and F.V. Fernandez
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2018
abstract
In this work, a CMOS transistor array for the massive measurement of random telegraph noise (RTN), together with a dedicated experimental setup, is presented. The array chip, called ENDURANCE, allows the massive characterization of the RTN parameters needed for a complete understanding of the phenomenon. Additionally, some experimental results are presented that demonstrate the convenience of the setup.
Weighted Time Lag Plot Defect Parameter Extraction and GPU-based BTI Modeling for BTI Variability
V.M. van Santen, J. Diaz-Fortuny, H. Amrouch, J. Martin-Martinez, R. Rodriguez, R. Castro-Lopez, E. Roca, F.V. Fernandez, J. Henkel and M. Nafria
Conference · IEEE International Reliability Physics Symposium IRPS 2018
abstract
Recent MOSFET devices exhibit a strong variability in their Bias Temperature Instability (BTI) induced degradation (e.g., Vth-shift). For identical stress patterns, each device exhibits unique degradation behavior. As BTI variability increases with shrinking device geometries, modeling BTI variability becomes essential. The challenge of modeling BTI variability is the significant time required to characterize a representative set of devices to properly calibrate the BTI variability model. In addition, (SPICE) circuit simulations under BTI variability are extremely time consuming. Both challenges originate from unique uncorrelated BTI behavior in each device. Each device features a unique set of defects with a unique state (occupied/unoccupied) in each defect. In this work, we tackle the characterization challenge by processing the data acquired from our parallel measurement setup with lightweight and fast defect extraction. Our novel weighted time lag plot defect parameter extraction, removes uncorrelated voltage noise and categorizes correlated noise (i.e., Random Telegraph Noise (RTN)) and discrete voltage steps (i.e., BTI). After the measurement data is processed, capture time, emission time and induced degradation of each defect can be extracted. After defect parameters are extracted, we can fit a bi-variate log-normal defect distribution and calibrate our BTI model. To employ a BTI variability model in circuit simulation, it must be able to model thousands of MOSFETs. Circuits consist of thousands of devices, each with unique behavior, resulting in computationally intensive modeling. Our GPU-based BTI variability model employs massive parallelism (beyond 1000 processing cores) found in graphic cards to model thousands of MOSFETs in seconds. Therefore, our novel defect parameter extraction methodology allows lightweight, yet accurate characterization of our model, while our model itself enables circuit simulations in large circuits as it models 100,000 MOSFETs in just 119s.
A noise and RTN-removal smart method for the parameter extraction of CMOS aging compact models
J. Diaz-Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca and F.V. Fernandez
Conference · Joint Int. EUROSOI Workshop and Int. Conf. on Ultimate Integration on Silicon EUROSOI-ULIS 2018
abstract
This work presents a new method to statistically characterize the emission times and threshold voltage shifts (ΔV th ) related to oxide defects in nanometer CMOS transistors during aging tests. The method identifies the V th drops associated to oxide trap emissions during BTI and HCI aging recovery traces while removing RTN and background noise contributions, to avoid artifacts during data analysis.
Statistical characterization of reliability effects in nanometer CMOS using a versatile transistor array IC
J. Díaz-Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca, F.V. Fernández, E. Barajas-Ojeda, X. Aragones and D. Mateo-Peña
Conference · Conference on Design of Circuits and Integrated Systems DCIS 2017
abstract
In this work, an experimental framework for the characterization of various reliability effects in modern CMOS technologies is described. The main element in this framework is a versatile transistor array chip, designed to accurately characterize process variability, Random Telegraph Noise and BTI/HCI related time dependent variability effects. The measurement setup, the other element in the framework, has been designed to take full advantage of the array architecture, which allows parallel testing of its 3136 MOS transistors, thereby reducing considerably the total measurement time. Thanks to a control toolbox and a user-friendly GUI, the setup also facilitates the programming of any of the required characterization tests.
A transistor array chip for the statistical characterization of process variability, RTN and BTI/CHC aging
J. Diaz-Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca, F.V. Fernandez, E. Barajas, X. Aragones and D. Mateo
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2017
abstract
In this work, a CMOS transistor array is presented, which allows performing process variability, Random Telegraph Noise and BTI/CHC aging characterization in a single chip. The array, called ENDURANCE, integrates 3136 MOS transistors, for single and massive electrical testing. This chip, together with a dedicated measurement set-up, allows programming any of these electrical tests, considerably reducing the total time needed for aging measurements by using a parallelization technique.
Statistical characterization of unreliability effects in a 65-nm CMOS transistor array
J. Diaz-Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca and F.V. Fernandez
Conference · International Mixed-Signals Testing Workshop IMSTW 2017
abstract
In this work, a CMOS transistor array is presented which enables characterization of variability, Random Telegraph Noise and BTI/CHC aging. The array integrates 3,136 MOS transistors for massive electrical testing. This array, together with a dedicated test setup with graphical interface feature easy programming of the required characterization tests, visualization of results and post-processing algorithms for the defect characterization required in aging modeling and simulation.
TARS: A toolbox for statistical reliability modeling of CMOS devices
J. Diaz-Fortuny, J. Martin-Martinez, R. Rodriguez, M. Nafria, R. Castro-Lopez, E. Roca and F.V. Fernandez
Conference · Int. Conf. on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design SMACD 2017
abstract
This paper presents a toolbox for the automation of the electrical characterization of CMOS transistors. The developed software provides a user-friendly interface to carry out different tests to evaluate time-zero (i.e., process) and time-dependent variability in CMOS devices. Also, the software incorporates a post-processing capability that allows users to visualize the data. Moreover, without loss of generality, the toolbox allows the user, from the measured data, to feed a particular physics-based model that accounts for various aging phenomena.
Dependence of MOSFETs threshold voltage variability on channel dimensions
C. Couso, J. Diaz-Fortuny, J. Martin-Martinez, M. Porti, R. Rodriguez, M. Nafria, F.V. Fernandez, E. Roca, R. Castro-Lopez, E. Barajas, D. Mateo and X. Aragones
Conference · Joint Int. EUROSOI Workshop and Int. Conf. on Ultimate Integration on Silicon EUROSOI-ULIS 2017
abstract
The dependence of the MOSFET threshold voltage variability on device geometry (width (W) and length (L)) has been studied from experimental data. Our results evidence, in agreement with other works, deviations from the Pelgrom's rule, especially in smaller technologies. TCAD simulations were also performed which further support the experimental data and provide physical information regarding the origin of such deviation. Finally, a new empirical model that assumes different impact of W and L in the device variability has been proposed, which reproduces the experimental results.
Books
No results
Book Chapters
Modeling of variability and reliability in analog circuits
J. Martin-Martinez, J. Diaz-Fortuny, A. Toro-Frias, P. Martin-Lloret, P. Saraza-Canflanca, R. Castro-Lopez, R. Rodriguez, E. Roca, F.V. Fernandez and M. Nafria
Book Chapter · Modelling Methodologies in Analogue Integrated Circuit Design, pp 179-206, 2020
abstract
doi
This chapter is divided into four sections. In Section 8.1, the probabilistic defect occupancy (PDO) model, a physics-based compact model, is introduced, which can be easily implemented into circuit simulators. Section 8.2 describes a purposely designed IC which contains suitable test structures, together with a full instrumentation system for the massive characterization of TZV and TDV in CMOS transistors, from which aging of the technology under study can be statistically evaluated. Section 8.3 is devoted to a smart methodology, which allows extracting the statistical distributions of the main physical parameters related to TDV from the measurements performed with the instrumentation system. Finally, Section 8.4 describes CASE, a new reliability simulation tool that accounts for TZV and TDV in analog circuits, covering important aspects, such as the device degradation evaluation, by means of stochastic modeling and the link between the device biasing and its degradation. As an example, the shifts of the performance of a Miller operational amplifier related to the device TDV is evaluated using CASE. Finally, in Section 8.5 the main conclusions are summarized.
Other publications
No results
