[papers] Aging and Device Reliability Compact Modeling

IEEE International Reliability Physics Symposium

(IRPS 2021)

[1] N. Chatterjee, J. Ortega, I. Meric, P. Xiao and I. Tsameret, "Machine Learning On Transistor Aging Data: Test Time Reduction and Modeling for Novel Devices," 2021 IEEE International Reliability Physics Symposium (IRPS), 2021, pp. 1-9, doi: 10.1109/IRPS46558.2021.9405188.

Abstract: Accurately modeling the I-V characteristics and current degradation for transistors is central to predicting circuit end-of-life behavior. In this work, we propose a machine learning model to accurately model current degradation at various stress conditions and extend that to make nominal use-bias predictions. The model can be extended to track and predict any parametric change. We show an excellent agreement of the model with experimental results. Furthermore, we use a deep neural network to model the I-V characteristics of aged transistors over a wide drain and gate playback bias range and show an excellent agreement with experimental results. We show that the model is reliably able to interpolate and extrapolate demonstrating that it learns the underlying functional form of the data.

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9405188&isnumber=9405088

[2] P. B. Vyas et al., "Reliability-Conscious MOSFET Compact Modeling with Focus on the Defect-Screening Effect of Hot-Carrier Injection," 2021 IEEE International Reliability Physics Symposium (IRPS), 2021, pp. 1-4, doi: 10.1109/IRPS46558.2021.9405197.

Abstract: Accurate prediction of device aging plays a vital role in the circuit design of advanced-node CMOS technologies. In particular, hot-carrier induced aging is so complicated that its modeling is often significantly simplified, with focus limited to digital circuits. We present here a novel reliability-aware compact modeling method that can accurately capture the full post-stress I-V characteristics of the MOSFET, taking into account the impact of drain depletion region on induced defects.

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9405197&isnumber=9405088

[3] Z. Wu et al., "Physics-based device aging modelling framework for accurate circuit reliability assessment," 2021 IEEE International Reliability Physics Symposium (IRPS), 2021, pp. 1-6, doi: 10.1109/IRPS46558.2021.9405106.

Abstract: An analytical device aging modelling framework, ranging from microscopic degradation physics up to the aged I-V characteristics, is demonstrated. We first expand our reliability oriented I-V compact model, now including temperature and body-bias effects; second, we propose an analytical solution for channel carrier profiling which-compared to our previous work-circumvents the need of TCAD aid; third, through Poisson's equation, we convert the extracted carrier density profile into channel lateral and oxide electric fields; fourth, we represent the device as an equivalent ballistic MOSFETs chain to enable channel “slicing” and propagate local degradation into the aged I-V characteristics, without requiring computationally-intensive self-consistent calculations. The local degradation in each channel “slice” is calculated with physics-based reliability models (2-state NMP, SVE/MVE). The demonstrated aging modelling framework is verified against TCAD and validated across a broad range of VG/VD/T stress conditions in a scaled finFET technology.

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9405106&isnumber=9405088

[paper] Aged MOSFET and Its Compact Modeling

F. A. Herrera, M. Miura-Mattausch, T. Iizuka, H. Kikuchihara, H. J. Mattausch and H. Takatsuka, Universal Feature of Trap-Density Increase in Aged MOSFET and Its Compact Modeling

SISPAD, Kobe, Japan, 2020, pp. 109-112

DOI: 10.23919/SISPAD49475.2020.9241674

Abstract: Our investigation focuses on accurate circuit aging prediction for bulk MOSFETs. A self-consistent aging modeling is proposed, which considers the trap-density Ntrap increase as the aging origin. This Ntrap is considered in the Poisson equation together with other charges induced within MOSFET. It is demonstrated that a universal relationship of the Ntrap increase as a function of integrated substrate current, caused by device stress, can describe the MOSFET aging in a simple way for any device-operating conditions. An exponential increase with constant and unitary slope of the Ntrap is found to successfully predict the aging phenomena, reaching a saturation for high stress degradation. The model universality is verified additionally for any device size. Comparison with existing conventional aging modeling for circuit simulation is discussed for demonstrating the simplifications due to the developed modeling approach

Fig: Schematic of the density-of-state (DOS) model as a function of the state-energy difference from the conduction-band edge, with two parameters gc and Es introduced as new model features.

[paper] Statistical model of the NBTI-induced ΔVth, ΔSS, and Δgm degradations in advanced pFinFETs

Statistical model of the NBTI induced threshold voltage, subthreshold swing, and transconductance degradations in advanced pFinFETs
J. Franco, B. Kaczer, S. Mukhopadhyay, P. Duhan, P. Weckx, Ph.J. Roussel, T. Chiarella, L.-Å. Ragnarsson, L. Trojman, N. Horiguchi, A. Spessot, D. Linten, A. Mocuta
2016 IEEE International Electron Devices Meeting (IEDM), San Francisco, CA, USA, 2016, pp. 15.3.1-15.3.4.
DOI: 10.1109/IEDM.2016.7838422

Abstract

We study the stochastic NBTI degradation of pFinFETs, in terms of ΔVth, ΔSS, and Δgm. We extend our Defect-Centric model to describe also the SS distribution in a population of devices of any area, at any stage of product aging. A large fraction of nanoscale devices is found to show a peak g m improvement after stress. We explain this effect in terms of the interaction of individual defects with the percolative channel conduction, and we propose a statistical description of g m aging. Our Vth, SS, and gm aging models are pluggable into reliability-enabled compact models to estimate design margins for a wide variety of circuits. Selected nanoscale device characteristics resulting from 3 percolation paths, generated with the EKV model [read more...]

[paper] Analysis of aging effects - From transistor to system level

Analysis of aging effects - From transistor to system level

Maike Taddiken*, Nico Hellwege, Nils Heidmann, Dagmar Peters-Drolshagen, Steffen Paul

Institute of Electrodynamics and Microelectronics,
University of Bremen, Otto-Hahn-Allee 1, Bremen 28359,Germany

ABSTRACT: Due to shrinking feature sizes in integrated circuits, additional reliability effects have to be considered which influence the functionality of the system. These effects can either result from the manufacturing process or external influences during the lifetime such as radiation and temperature. Additionally, modern technology nodes are affected by time-dependent degradation i.e. aging. Due to the age-dependent degradation of a circuit, processes on the atomic scale of the semiconductor material lead to charges in the oxide silicon interface of CMOS devices, altering the performance parameters of the device and subsequently the behavior of the circuit. With the continuous downscaling of modern semiconductor technologies, the impact of these atomic scale processes affecting the overall system characteristics becomes more and more critical. Therefore, aging effects need to be assessed during the design phase and actions have to be taken guaranteeing the correct system functionality throughout a system’s lifetime. This work presents methods to investigate the influence of age-dependent degradation as well as process variability on different levels. An operating-point dependent sizing methodology based on the gm/ID method extended to incorporate aging, which aims at developing aging-resistent circuits is presented. The basic idea of the gm/ID sizing method is the dependence of the operating point of a MOS transistor on the state of inversion in the channel, its strong relation to circuit performance and the possibility to calculate transistor dimensions.The inversion coefficient IC is a fundamental metric within the gm/ID method and numerically represents the inversion level of a MOS device formally described in the EKV MOS model. Additionally, the sensitivity of circuit performances in regard to aging can be determined. In order to investigate the reliability of a complex system on behavioral level, a modeling method to represent the performance of system components in dependence of aging and process variability is introduced. [read more...]