Charge trapping in ultrathin hafnium silicate/metal gate stacks

P. Srinivasan; N. A. Chowdhury; D. Misra

doi:10.1109/LED.2005.859677

Charge trapping in ultrathin hafnium silicate/metal gate stacks

P. Srinivasan, N. A. Chowdhury, D. Misra

Electrical and Computer Engineering

Research output: Contribution to journal › Article › peer-review

6 Scopus citations

Abstract

Charge trapping characteristics of MOCVD HfSi_xO_y (20% SiO₂) gate stack of n-MOSFETs during substrate injection have been investigated. Positive constant voltage stress (CVS) and constant current stress (CCS) were applied at the gate of TiN-HfSi_xO_y-SiO₂/p-Si n-MOSFETs having EOT of 2 nm. Significant electron trapping is observed from the positive shift of threshold voltage (ΔV_t) after stress. Curve fitting of the threshold voltage shift data confirms power law dependence for Hf-silicate gate stacks. Charge pumping measurements for both cases showed significant electron trapping at bulk Hf-silicate while interface trap generation was comparatively insignificant. A turn-around effect is noticed for ΔV_t as the stress current and voltage increases under CCS and CVS. Dependence of spatial distribution of charge trapping at shallow traps on stress level in the Hf-silicate film and redistribution of trapped charges during and after removal of stress is possibly responsible for the turn-around effect.

Original language	English (US)
Pages (from-to)	913-915
Number of pages	3
Journal	IEEE Electron Device Letters
Volume	26
Issue number	12
DOIs	https://doi.org/10.1109/LED.2005.859677
State	Published - Dec 2005

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

Keywords

Charge pumping
Charge trapping
Hafnium silicate
High-k
Metal gate
Substrate injection

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10.1109/LED.2005.859677

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title = "Charge trapping in ultrathin hafnium silicate/metal gate stacks",

abstract = "Charge trapping characteristics of MOCVD HfSixOy (20% SiO2) gate stack of n-MOSFETs during substrate injection have been investigated. Positive constant voltage stress (CVS) and constant current stress (CCS) were applied at the gate of TiN-HfSixOy-SiO2/p-Si n-MOSFETs having EOT of 2 nm. Significant electron trapping is observed from the positive shift of threshold voltage (ΔVt) after stress. Curve fitting of the threshold voltage shift data confirms power law dependence for Hf-silicate gate stacks. Charge pumping measurements for both cases showed significant electron trapping at bulk Hf-silicate while interface trap generation was comparatively insignificant. A turn-around effect is noticed for ΔVt as the stress current and voltage increases under CCS and CVS. Dependence of spatial distribution of charge trapping at shallow traps on stress level in the Hf-silicate film and redistribution of trapped charges during and after removal of stress is possibly responsible for the turn-around effect.",

keywords = "Charge pumping, Charge trapping, Hafnium silicate, High-k, Metal gate, Substrate injection",

author = "P. Srinivasan and Chowdhury, {N. A.} and D. Misra",

note = "Funding Information: Manuscript received September 13, 2005. This work was supported by the National Science Foundation under Award ECS-0140584. The review of this letter was arranged by Editor E. Sangiorgi. The authors are with the Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 USA (e-mail: dmisra@njit.edu). Digital Object Identifier 10.1109/LED.2005.859677",

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AU - Chowdhury, N. A.

AU - Misra, D.

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N2 - Charge trapping characteristics of MOCVD HfSixOy (20% SiO2) gate stack of n-MOSFETs during substrate injection have been investigated. Positive constant voltage stress (CVS) and constant current stress (CCS) were applied at the gate of TiN-HfSixOy-SiO2/p-Si n-MOSFETs having EOT of 2 nm. Significant electron trapping is observed from the positive shift of threshold voltage (ΔVt) after stress. Curve fitting of the threshold voltage shift data confirms power law dependence for Hf-silicate gate stacks. Charge pumping measurements for both cases showed significant electron trapping at bulk Hf-silicate while interface trap generation was comparatively insignificant. A turn-around effect is noticed for ΔVt as the stress current and voltage increases under CCS and CVS. Dependence of spatial distribution of charge trapping at shallow traps on stress level in the Hf-silicate film and redistribution of trapped charges during and after removal of stress is possibly responsible for the turn-around effect.

AB - Charge trapping characteristics of MOCVD HfSixOy (20% SiO2) gate stack of n-MOSFETs during substrate injection have been investigated. Positive constant voltage stress (CVS) and constant current stress (CCS) were applied at the gate of TiN-HfSixOy-SiO2/p-Si n-MOSFETs having EOT of 2 nm. Significant electron trapping is observed from the positive shift of threshold voltage (ΔVt) after stress. Curve fitting of the threshold voltage shift data confirms power law dependence for Hf-silicate gate stacks. Charge pumping measurements for both cases showed significant electron trapping at bulk Hf-silicate while interface trap generation was comparatively insignificant. A turn-around effect is noticed for ΔVt as the stress current and voltage increases under CCS and CVS. Dependence of spatial distribution of charge trapping at shallow traps on stress level in the Hf-silicate film and redistribution of trapped charges during and after removal of stress is possibly responsible for the turn-around effect.

KW - Charge pumping

KW - Charge trapping

KW - Hafnium silicate

KW - High-k

KW - Metal gate

KW - Substrate injection

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Charge trapping in ultrathin hafnium silicate/metal gate stacks

Abstract

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Keywords

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