Charge trapping in ultrathin hafnium silicate/metal gate stacks

Document Type

Article

Publication Date

12-1-2005

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. © 2005 IEEE.

Identifier

29244440732 (Scopus)

Publication Title

IEEE Electron Device Letters

External Full Text Location

https://doi.org/10.1109/LED.2005.859677

ISSN

07413106

First Page

913

Last Page

915

Issue

12

Volume

26

Grant

ECS-0140584

Fund Ref

National Science Foundation

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