Hydrogen Impacts of PEALD InGaZnO TFTs Using SiOx Gate Insulators Deposited by PECVD and PEALD

Amorphous indium gallium zinc oxide (IGZO) deposited by plasma-enhanced atomic layer deposition (PEALD) thin-film transistors (TFTs) was fabricated using SiO 2 gate insulators synthesized via plasma-enhanced chemical vapor deposition (PECVD, device A) or PEALD (device B). The electrical performance...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2020-10, Vol.67 (10), p.4250-4255
Main Authors: Jeong, Seok-Goo, Jeong, Hyun-Jun, Choi, Wan-Ho, Kim, KyoungRok, Park, Jin-Seong
Format: Article
Language:English
Subjects:
Atomic layer epitaxy
Backscattering
Chemical synthesis
Fourier transforms
Gallium
Hydrogen
Hydrogen bonding
Indium gallium zinc oxide
Infrared spectroscopy
Insulators
Logic gates
Oxide semiconductor
Photoelectrons
Plasma enhanced chemical vapor deposition
Plasma temperature
plasma-enhanced atomic layer deposition (PEALD)
Recoil
Rutherford backscattering spectroscopy
Semiconductor devices
Silicon dioxide
Spectroscopy
Spectrum analysis
subchannel formation by hydrogen diffusion
Thin film transistors
thin-film transistors (TFTs)
Threshold voltage
X ray photoelectron spectroscopy
Zinc oxide
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Summary:Amorphous indium gallium zinc oxide (IGZO) deposited by plasma-enhanced atomic layer deposition (PEALD) thin-film transistors (TFTs) was fabricated using SiO 2 gate insulators synthesized via plasma-enhanced chemical vapor deposition (PECVD, device A) or PEALD (device B). The electrical performance of B devices was higher than that of device A. The mobilities of A and B devices were 19.39 and 21.11 cm 2 /Vs, and the subthreshold slopes were 0.25 and 0.22 V /decade, respectively. In addition, the device reliability of A devices shows an abnormal threshold voltage ( {V}_{\text {th}} ) shift of -1.25 V under positive bias temperature stress (PBTS), caused by hydrogen diffusion from the gate insulator to the channel region near the source/drain electrode. However, B devices had a normal {V}_{\text {th}} shift of +2.87 V. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR) results showed that PECVD SiO 2 has a large amount of hydrogen bonding, such as Si-OH, compared to PEALD SiO 2 . Rutherford backscattering spectroscopy (RBS) and elastic recoil detection (ERD) measurement results confirmed that the hydrogen content of PECVD SiO 2 was 2.24%, whereas that of PEALD SiO 2 was lower at 1.45%.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2020.3017145