The influence of active layer sputtering process and annealing temperature on the electrical properties of IZO TFT

Wang Cong; Ding Youkun; Liu Yurong

doi:10.12086/oee.2024.240077

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Wang C, Ding Y K, Liu Y R. The influence of active layer sputtering process and annealing temperature on the electrical properties of IZO TFT[J]. Opto-Electron Eng, 2024, 51(6): 240077. doi: 10.12086/oee.2024.240077

Citation:

Wang C, Ding Y K, Liu Y R. The influence of active layer sputtering process and annealing temperature on the electrical properties of IZO TFT[J]. Opto-Electron Eng, 2024, 51(6): 240077. doi: 10.12086/oee.2024.240077

The influence of active layer sputtering process and annealing temperature on the electrical properties of IZO TFT

1.
Post-Doctoral Research Station, Shanwei Marine Industry Institute, Shanwei, Guangdong 516600, China
2.
School of Microelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
3.
School of Engineering, Shanwei Institute of Technology, Shanwei, Guangdong 516600, China

Fund Project: Project supported by Special Project in Key Fields of the Higher Education Institutions of Guangdong Province (the New Generation of Communication Technology) (2020ZDZX3125), National Natural Science Foundation of China (61871195), and Basic and Applied Basic Research Foundation of Guangdong Province (2024A1515011719)

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^*Corresponding author: phlyr@scut.edu.cn

Received Date 28 March 2024

Revised Date 14 May 2024

Accepted Date 16 May 2024

Published Date 25 June 2024

Abstract

Abstract

In order to improve the electrical performance of oxide thin film transistors, In-doped ZnO thin film transistors (IZO TFT) were prepared by using a sputtered IZO thin film as the active layer and an Al₂O₃ thin film deposited by atomic layer deposition (ALD) as the gate dielectric layer. The effects of the ratio of argon and oxygen, sputtering gas pressure, and annealing temperature on the electrical properties of IZO TFT were investigated during the IZO film preparation process. The results indicated that the IZO TFT, which was prepared at the appropriate argon-oxygen ratio and reaction pressure under relatively high annealing temperatures, shows excellent electrical characteristics. When the argon oxygen flow rate ratio was 60:20 sccm, the sputtering gas pressure was 0.5 Pa, and the air annealing temperature and time were 250 ℃ and 1 hour, respectively. The electrical properties of the IZO TFT were relatively better with a carrier saturation mobility of 31 cm²/(V·s) and a high on-off current ratio of 10⁸. A relatively too-low or too-high argon-oxygen ratio could cause too-low or too-high oxygen vacancies in the active layer of IZO, thus reducing TFT device performance. The low annealing temperature couldn't transform the Al-OH bonds in the gate dielectric layer into Al-O bonds, and was difficult for oxygen in the air to diffuse into IZO and passivate oxygen vacancies, thus leading to poor device performance.
- indium zinc oxide /
- thin film transistor /
- process parameters /
- electrical performance

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References

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Overview

Overview

In order to improve the electrical performance of oxide thin film transistors, In-doped ZnO thin film transistors (IZO TFT) were prepared by using a sputtered IZO thin film as the active layer and an Al₂O₃ thin film deposited by atomic layer deposition (ALD) as the gate dielectric layer. The effects of the ratio of argon and oxygen, sputtering gas pressure, and annealing temperature on the electrical properties of IZO TFT were investigated during the IZO film preparation process. The results indicated that the IZO TFT, which was prepared at the appropriate argon-oxygen ratio and reaction pressure under relatively high annealing temperatures, shows excellent electrical characteristics. When the argon oxygen flow rate ratio was 60:20 sccm, the sputtering gas pressure was 0.5 Pa, and the air annealing temperature and time were 250 ℃ and 1 hour, respectively. The electrical properties of the IZO TFT were relatively better with a carrier saturation mobility of 31 cm²/(V·s) and a high on-off current ratio of 10⁸. A relatively too-low or too-high argon-oxygen ratio could cause too-low or too-high oxygen vacancies in the active layer of IZO, thus reducing TFT device performance. The low annealing temperature couldn't transform the Al-OH bonds in the gate dielectric layer into Al-O bonds, and was difficult for oxygen in the air to diffuse into IZO and passivate oxygen vacancies, thus leading to poor device performance. The IZO TFTs couldn't exhibit gate voltage control characteristics. When the annealing temperature was higher, it was beneficial to increase the density of IZO thin films, reduce the defect states inside and on the surface, and thus obtain high-performance IZO TFTs.