Influence of Channel Surface with Ozone Annealing and UV Treatment on the Electrical Characteristics of Top-Gate InGaZnO Thin-Film Transistors

The effect of the channel interface of top-gate InGaZnO (IGZO) thin film transistors (TFTs) on the electrical properties caused by exposure to various wet chemicals such as deionized water, photoresist (PR), and strippers during the photolithography process was studied. Contrary to the good electric...

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Bibliographic Details
Published in:Materials 2023-09, Vol.16 (18), p.6161
Main Authors: Oh, Changyong, Kim, Taehyeon, Ju, Myeong Woo, Kim, Min Young, Park, So Hee, Lee, Geon Hyeong, Kim, Hyunwuk, Kim, SeHoon, Kim, Bo Sung
Format: Article
Language:English
Subjects:
Air pollution
Annealing
Chemical damage
Chemical reactions
Chemicals
Circuit components
Contamination
Current voltage characteristics
Defect annealing
Deionization
Dielectric films
Electric properties
Electrical properties
Indium gallium zinc oxide
Morphology
Organic light emitting diodes
Oxygen
Ozone
Photolithography
Photoresists
Semiconductor devices
Silicon wafers
Spectrum analysis
Thin film transistors
Thin films
Threshold voltage
Transistors
Ultraviolet radiation
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Summary:The effect of the channel interface of top-gate InGaZnO (IGZO) thin film transistors (TFTs) on the electrical properties caused by exposure to various wet chemicals such as deionized water, photoresist (PR), and strippers during the photolithography process was studied. Contrary to the good electrical characteristics of TFTs including a protective layer (PL) to avoid interface damage by wet chemical processes, TFTs without PL showed a conductive behavior with a negative threshold voltage shift, in which the ratio of Ga and Zn on the IGZO top surface reduced due to exposure to a stripper. In addition, the wet process in photolithography increased oxygen vacancy and oxygen impurity on the IGZO surface. The photo-patterning process increased donor-like defects in IGZO due to organic contamination on the IGZO surface by PR, making the TFT characteristics more conductive. The introduction of ozone (O3) annealing after photo-patterning and stripping of IGZO reduced the increased defect states on the surface of IGZO due to the wet process and effectively eliminated organic contamination by PR. In particular, by controlling surface oxygens on top of the IGZO surface excessively generated with O3 annealing using UV irradiation of 185 and 254 nm, IGZO TFTs with excellent current–voltage characteristics and reliability could be realized comparable to IGZO TFTs containing PL.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma16186161