Probing technique for energy distribution of positive charges in gate dielectrics and its application to lifetime prediction
type: CreativeWork
description: The continuous reduction of the dimensions of CMOS devices has increased the negative bias temperature instability (NBTI) of pMOSFETs to such a level that it is limiting their lifetime. This increase of NBTI is caused mainly by three factors: an increase of nitrogen concentration in gate dielectric, a higher operation electrical field, and a higher temperature. Despite of many years’ research work, there are questions on the correctness of the NBTI lifetime predicted through voltage acceleration and extrapolation. The conventional lifetime prediction technique measures the degradation slowly and it typically takes 10 ms or longer to record one threshold voltage shift. It has been reported that NBTI can recover substantially in this time and the degradation is underestimated. To minimize the recovery, ultra-fast technique has been developed and the measurement time has been reduced to the order of microseconds. Once the recovery is suppressed, however, the degradation no longer follows a power law and there is no industry-wide accepted method for lifetime prediction. The objective of this project is to overcome this challenge and to develop a reliable NBTI lifetime prediction technique after freezing the recovery. To achieve this objective, it is essential to have an in-depth knowledge on the defects responsible for the recovery. It has been generally accepted that the NBTI recovery is dominated by the discharge of trapped holes. For the thin dielectric (e.g. < 3 nm) used by current industry, all hole traps are within direct tunnelling distance from the substrate and their discharging is mainly controlled by their energy levels against the Fermi level at the substrate interface. As a result, it is crucial to have the energy distribution of positive charges (PC) in the gate dielectric, but there is no technique available for probing this energy profile. A major achievement of this project is to develop a new technique that can probe the energy distribution of PCs both…
abstract: The continuous reduction of the dimensions of CMOS devices has increased the negative bias temperature instability (NBTI) of pMOSFETs to such a level that it is limiting their lifetime. This increase of NBTI is caused mainly by three factors: an increase of nitrogen concentration in gate dielectric, a higher operation electrical field, and a higher temperature. Despite of many years’ research work, there are questions on the correctness of the NBTI lifetime predicted through voltage acceleration and extrapolation. The conventional lifetime prediction technique measures the degradation slowly and it typically takes 10 ms or longer to record one threshold voltage shift. It has been reported that NBTI can recover substantially in this time and the degradation is underestimated. To minimize the recovery, ultra-fast technique has been developed and the measurement time has been reduced to the order of microseconds. Once the recovery is suppressed, however, the degradation no longer follows a power law and there is no industry-wide accepted method for lifetime prediction. The objective of this project is to overcome this challenge and to develop a reliable NBTI lifetime prediction technique after freezing the recovery. To achieve this objective, it is essential to have an in-depth knowledge on the defects responsible for the recovery. It has been generally accepted that the NBTI recovery is dominated by the discharge of trapped holes. For the thin dielectric (e.g. < 3 nm) used by current industry, all hole traps are within direct tunnelling distance from the substrate and their discharging is mainly controlled by their energy levels against the Fermi level at the substrate interface. As a result, it is crucial to have the energy distribution of positive charges (PC) in the gate dielectric, but there is no technique available for probing this energy profile. A major achievement of this project is to develop a new technique that can probe the energy distribution of PCs both…
author: Hatta, SFWM
keywords: TK Electrical engineering. Electronics. Nuclear engineering
date published: 2013
date modified: 2026-07-24T06:30:00Z
provider: Liverpool Jon Moores University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Liverpool John Moores University

PropertyValue
property ID: DOI
value: 10.24377/LJMU.t.00004528