Effect of interfacial excess oxygen on positive-bias temperature stress instability of self-aligned coplanar InGaZnO thin-film transistors

We investigated the impact of excess oxygen on positive bias temperature stress (PBTS) instability of self-aligned coplanar amorphous InGaZnO thin-film transistors. We focus on the interface region which is compositionally differentiated from the bulk material on each side. The threshold voltage shi...

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Bibliographic Details
Published in:Applied physics letters 2016-04, Vol.108 (14)
Main Authors: Oh, Saeroonter, Baeck, Ju Heyuck, Bae, Jong Uk, Park, Kwon-Shik, Kang, In Byeong
Format: Article
Language:English
Subjects:
Applied physics
Bias
CAPACITANCE
CATIONS
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
DENSITY
ELECTRIC POTENTIAL
Electrical measurement
Electron traps
INSTABILITY
Interface stability
INTERFACES
METALS
MINIMIZATION
MONOCHROMATIC RADIATION
OXYGEN
Self alignment
Semiconductor devices
STRESSES
Thin film transistors
THIN FILMS
Threshold voltage
TRANSISTORS
TRAPS
VISIBLE RADIATION
WAVELENGTHS
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Summary:We investigated the impact of excess oxygen on positive bias temperature stress (PBTS) instability of self-aligned coplanar amorphous InGaZnO thin-film transistors. We focus on the interface region which is compositionally differentiated from the bulk material on each side. The threshold voltage shift under PBTS is proportional to the extracted density of interface trap states that act as electron traps. The density of interface trap states is extracted from capacitance-voltage measurements with monochromatic light of varying wavelengths. We introduce a figure-of-merit that quantifies the amount of excess oxygen relative to the metal cation composition in the interface region. Minimization of interfacial excess oxygen from 112.4% to 101.2% reduces the density of interface trap states by a factor of 2.77, resulting in improvement of PBTS instability from a threshold voltage shift value of 4.42 V to 0.35 V.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4945404