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Zheng S, Lv S, Wang C, Li Z, Dong L, Xin Q, Song A, Zhang J, Li Y. Post-annealing effect of low temperature atomic layer deposited Al 2O 3on the top gate IGZO TFT. NANOTECHNOLOGY 2024; 35:155203. [PMID: 38198735 DOI: 10.1088/1361-6528/ad1d16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 01/10/2024] [Indexed: 01/12/2024]
Abstract
Electronical properties of top gate amorphous InGaZnO4thin film transistors (TFTs) could be controlled by post-annealing treatment, which has a great impact on the Al2O3insulator. To investigate the effect of post-annealing on Al2O3, Al/Al2O3/p-Si MOS capacitoras with Al2O3films treated under various post-deposition annealing (PDA) temperature were employed to analysis the change of electrical properties, surface morphology, and chemical components by electrical voltage scanning, atomic force microscope (AFM), and x-ray photoelectron spectroscopy (XPS) technologies. After PDA treatment, the top gate TFTs had a mobility about 7 cm2V-1s-1and the minimum subthreshold swing (SS) about 0.11 V/dec, and the threshold voltage (Vth) shifted from positive direction to negative direction as the post-annealing temperature increased. Electrical properties of MOS capacitors revealed the existence of positive fixed charges and the variation of trap state density with increasing PDA temperature, and further explained the change of negative bias stress (NBS) stability in TFT. AFM results clarified the increased leakage current, degraded SS, and NBS stability in MOS capacitors and TFTs, respectively. XPS results not only illuminated the origin of fixed charges and the trap density variation with PDA temperatures of Al2O3films, but also showed the O and H diffusion from Al2O3into IGZO during post-annealing process, which led to the deviation ofVth, the change of current density, and the negativeVthshift after positive bias stress in TFTs.
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Affiliation(s)
- Shuaiying Zheng
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Shaocong Lv
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Chengyuan Wang
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Zhijun Li
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Liwei Dong
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Qian Xin
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
- State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China
| | - Aimin Song
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
- School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Jiawei Zhang
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
| | - Yuxiang Li
- Shandong Technology Center of Nanodevices and Integration, and School of Integrated Circuits, Shandong University, Jinan 250101, People's Republic of China
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Jang Y, Lee J, Mok J, Park J, Shin SY, Lee SY. Suppression of the redox reaction between the IGZO surface and the reducing agent TMA using fluorine oxidizing agent treatment. RSC Adv 2023; 13:33269-33275. [PMID: 37964900 PMCID: PMC10641534 DOI: 10.1039/d3ra06768h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 10/31/2023] [Indexed: 11/16/2023] Open
Abstract
We propose that the post-deposition oxidation of the IGZO surface is essential for improving the interface quality, with Al2O3 prepared by atomic layer deposition (ALD) employing a common metal precursor trimethylaluminum (TMA). Here, the ALD-Al2O3 process was conducted using H2O as an oxidant at a substrate temperature of 150 °C after IGZO deposition. The depth-resolved X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) data reveal the defect-rich and poor interface of the standard Al2O3/IGZO stack due to the redox reaction between the IGZO surface and TMA. The anion character of the IGZO was modified by introducing fluorine, which is known as a stability enhancer for oxide semiconductors. We highlight that the presence of the fluorine also improves the interface quality with ALD-Al2O3. As a consequence of the fluorine incorporation prior to the ALD-Al2O3 process, the chemical reduction reaction of the IGZO surface was effectively alleviated, resulting in a defect-passivated and sharp interface owing to the strong oxidizing nature of the fluorine.
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Affiliation(s)
- Yuseong Jang
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Jinkyu Lee
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Jinsung Mok
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Junhyeong Park
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Seung Yoon Shin
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Soo-Yeon Lee
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
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Oh C, Kim T, Ju MW, Kim MY, Park SH, Lee GH, Kim H, Kim S, Kim BS. Influence of Channel Surface with Ozone Annealing and UV Treatment on the Electrical Characteristics of Top-Gate InGaZnO Thin-Film Transistors. MATERIALS (BASEL, SWITZERLAND) 2023; 16:6161. [PMID: 37763439 PMCID: PMC10532450 DOI: 10.3390/ma16186161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/06/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023]
Abstract
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.
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Affiliation(s)
- Changyong Oh
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
- E·ICT-Culture·Sports Track, Korea University, Sejong 30019, Republic of Korea
| | - Taehyeon Kim
- Memory Diffusion Technology Team, Samsung Electronics, Pyeongtaek-si 17786, Republic of Korea;
| | - Myeong Woo Ju
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
- E·ICT-Culture·Sports Track, Korea University, Sejong 30019, Republic of Korea
| | - Min Young Kim
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
| | - So Hee Park
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
| | - Geon Hyeong Lee
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
| | - Hyunwuk Kim
- Display Development Division, ENF Technology Co., Ltd., Yongin-si 17084, Republic of Korea; (H.K.); (S.K.)
| | - SeHoon Kim
- Display Development Division, ENF Technology Co., Ltd., Yongin-si 17084, Republic of Korea; (H.K.); (S.K.)
| | - Bo Sung Kim
- Department of Applied Physics, Korea University, Sejong 30019, Republic of Korea; (C.O.); (M.W.J.); (M.Y.K.); (S.H.P.); (G.H.L.)
- E·ICT-Culture·Sports Track, Korea University, Sejong 30019, Republic of Korea
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Li J, Guan Y, Li J, Zhang Y, Zhang Y, Chan M, Wang X, Lu L, Zhang S. Ultra-thin gate insulator of atomic-layer-deposited AlO xand HfO xfor amorphous InGaZnO thin-film transistors. NANOTECHNOLOGY 2023; 34:265202. [PMID: 36962937 DOI: 10.1088/1361-6528/acc742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 03/24/2023] [Indexed: 06/18/2023]
Abstract
To strengthen the downscaling potential of top-gate amorphous oxide semiconductor (AOS) thin-film transistors (TFTs), the ultra-thin gate insulator (GI) was comparatively implemented using the atomic-layer-deposited (ALD) AlOxand HfOx. Both kinds of high-kGIs exhibit good insulating properties even with the physical thickness thinning to 4 nm. Compared to the amorphous indium-gallium-zinc oxide (a-IGZO) TFTs with 4 nm AlOxGI, the 4 nm HfOxenables a larger GI capacitance, while the HfOx-gated TFT suffers higher gate leakage current and poorer subthreshold slope, respectively originating from the inherently small band offset and the highly defective interface between a-IGZO and HfOx. Such imperfect a-IGZO/HfOxinterface further causes noticeable positive bias stress instability. Both ALD AlOxand HfOxwere found to react with the underneath a-IGZO channel to generate the interface defects, such as metal interstitials and oxygen vacancies, while the ALD process of HfOxgives rise to a more severe reduction of a-IGZO. Moreover, when such a defective interface is covered by the top gate, it cannot be readily restored using the conventional oxidizing post-treatments and thus desires the reduction-resistant pre-treatments of AOSs.
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Affiliation(s)
- Jiye Li
- School of Electronic and Computer Engineering, Peking University, Shenzhen, People's Republic of China
| | - Yuhang Guan
- School of Electronic and Computer Engineering, Peking University, Shenzhen, People's Republic of China
| | - Jinxiong Li
- School of Advanced Materials, Peking University, Shenzhen, People's Republic of China
| | - Yuqing Zhang
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
| | - Yuhan Zhang
- School of Electronic and Computer Engineering, Peking University, Shenzhen, People's Republic of China
| | - ManSun Chan
- Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
| | - Xinwei Wang
- School of Advanced Materials, Peking University, Shenzhen, People's Republic of China
| | - Lei Lu
- School of Electronic and Computer Engineering, Peking University, Shenzhen, People's Republic of China
| | - Shengdong Zhang
- School of Electronic and Computer Engineering, Peking University, Shenzhen, People's Republic of China
- School of Integrated Circuits, Peking University, Beijing, People's Republic of China
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