A generalized EKV charge-based MOSFET model including oxide and interface traps

https://doi.org/10.1016/j.sse.2020.107951Get rights and content
Under a Creative Commons license
open access

Highlights

  • This work presents a generalized EKV charge-based MOSFET model that includes the effects of trapped charges in the oxide bulk and at the silicon/oxide interface- and can be applied for modeling effects of total ionizing dose, bias-temperature instability, and hot-carrier injection.

  • In the presence of oxide- and interface-trapped charges, the mobile charge density at a given gate-to-bulk voltage can still be linearized but with respect to both the surface potential and the channel voltage, which enables us to derive explicit expressions for the charge-voltage relation, the current-charge relation, and crucial device parameters.

  • The proposed charge-based analytical model, including the effect of velocity saturation, is successfully validated against a 28-nm bulk CMOS technology with pre-radiation and radiation measurements of various MOSFETs up to 1 Grad(SiO2) of total ionizing dose.

  • Despite a small number of parameters, the model accurately captures the effects of radiation-induced oxide- and interface-trapped charges, resulting in an excellent fit with measurement results over a wide range of device operation from weak to strong inversion.

  • Explicit expressions of device parameters allow for the extraction of the oxide- and interface-trapped charge densities at each radiation step, which can serve for compact modeling of total ionizing radiation effects.

Abstract

This paper presents a generalized EKV charge-based MOSFET model that includes the effects of trapped charges in the oxide bulk and at the silicon/oxide interface. It is shown that in the presence of oxide- and interface-trapped charges, the mobile charge density can still be linearized but with respect to both the surface potential and the channel voltage. This enables us to derive closed-form expressions for the mobile charge density and the drain current. These simple formulations demonstrate the effects of charge trapping on MOSFET characteristics and crucial device parameters. The proposed charge-based analytical model, including the effect of velocity saturation, is successfully validated through measurements performed on devices from a 28-nm bulk CMOS technology. Ultrahigh total ionizing doses up to 1 Grad(SiO2) are applied to generate oxide-trapped charges and activate passivated interface traps. Despite a small number of parameters, the model is capable of accurately capturing measurement results over a wide range of device operation from weak to strong inversion. Explicit expressions of device parameters also allow for the extraction of the oxide- and interface-trapped charge densities.

Keywords

Charge-based modeling
Charge-trapping
Defects
Device reliability
EKV
Interface traps
Mobile charge linearization
Oxide-trapped charges
28-nm bulk MOSFETs
Radiation damage
Total ionizing dose

Cited by (0)

Chun-Min Zhang received her M. Sc. in Microelectronics and Solid-State Electronics from Fudan University, China in 2014. Since 2015, she has been a doctoral assistant in Integrated Circuits Laboratory (ICLAB), École Polytechnique Fédérale de Lausanne (EPFL), Switzerland. She is now working on characterization and modeling of total ionizing dose effects on nanoscale MOSFETs for particle physics experiments.

Christian Enz PhD, Swiss Federal Institute of Technology (EPFL), 1989. He is currently Professor at EPFL, Director of the Institute of Microengineering and head of the IC Lab. Until April 2013 he was VP at the Swiss Center for Electronics and Microtechnology (CSEM) in Neuchatel, Switzerland where he was heading the Integrated and Wireless Systems Division. Prior to joining CSEM, he was Principal Senior Engineer at Conexant (formerly Rockwell Semiconductor Systems), Newport Beach, CA, where he was responsible for the modeling and characterization of MOS transistors for RF applications. His technical interests and expertise are in the field of ultra low-power and low-noise analog and RF IC design and semiconductor device modeling. Together with E. Vittoz and F. Krummenacher he is the developer of the EKV MOS transistor model. He is the author and co-author of more than 260 scientific papers and has contributed to numerous conference presentations and advanced engineering courses. He is an IEEE Fellow and an individual member of the Swiss Academy of Engineering Sciences (SATW). He has been an elected member of the IEEE Solid-State Circuits Society (SSCS) AdCom from 2012 to 2014 and was Chair of the IEEE SSCS Chapter of Switzerland until 2017.