Cyclical Annealing Technique To Enhance Reliability of Amorphous Metal Oxide Thin Film Transistors

Chen, Hong Chih; Chang, Ting Chang; Lai, Wei Chih; Chen, Guan Fu; Chen, Bo Wei; Hung, Yu Ju; Chang, Kuo Jui; Cheng, Kai‐Chun; Huang, Chen Shuo; Chen, Kuo Kuang; Lu, Hsueh Hsing; Lin, Yu Hsin

doi:10.1021/acsami.7b16307

Cited by 20 publications

(6 citation statements)

References 18 publications

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“…This experiment was the same as those used in previous works . In our experiment, we used a bottom gate a-IGZO TFTs prepared with an inverted staggered etch stop layer (ESL) structure fabricated on the glass substrate.…”

Section: Experimental Devicesmentioning

confidence: 99%

“…This experiment was the same as those used in previous works. 22 In our experiment, we used a bottom gate a-IGZO TFTs prepared with an inverted staggered etch stop layer (ESL) structure fabricated on the glass substrate. First, a Ti/Al/Ti (50/200/50 nm) film was deposited by sputtering with Ar ion and wet-etched to form the bottom gate electrode.…”

Section: ■ Experimental Devicesmentioning

confidence: 99%

“…These factors suggest that a-IGZO TFTs are appropriate materials to aid in energy savings in future display technology. Recently a-IGZO has been studied extensively, but some of their problems and instabilities still require investigation, especially those involving moisture, − electrical field stresses, − and light-induced effects. − In addition, a-IGZO is environmentally sensitive. Many previous studies have reported that the use of oxides such as SiO 2 , Y 2 O 3 , Al 2 O 3 , HfO 2 , and MgO as passivation layers can effectively reduce atmosphere-induced instabilities. − Considering cost and compatibility, most industrial electronic applications use SiO 2 for such layers.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Capacitance–Voltage Electrical Characteristics of Thin-Film Transistors Caused by Hydrogen Diffusion under Negative Bias Stress in a Moist Environment

Chen

Kuo

Chang

et al. 2019

ACS Appl. Mater. Interfaces

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In this study, the impact of moisture on the electrical characteristics of an amorphous In–Ga–Zn–O thin-film transistor (a-IGZO TFT) was investigated. In commercial applications of such TFTs, high stability and quality performance in humid environments are essential. During TFT operation under ambient moisture, the electrolysis of water molecules occurs via the tip electric field effect. Hydrogen diffuses from the etch-stop layer or back-channel into the main channel under a negative electric field. The hydrogen atoms act as shallow donors (which causes the carrier concentration in the channel to rise), causing the threshold voltage (VTH) to shift in the negative direction. Hydrogen diffusion from the overlap of the source/drain and gate electrodes to the channel center caused by the tip electric field induces a significant barrier lowering and VTH shifts in a short-channel device. However, under negative bias stress (NBS) in ambient moisture, the negative VTH shift is more obvious in short- than in long-channel devices, indicating suppressed hydrogen diffusion in long-channel devices. This is attributed to the electrolysis of water by the tip electric field at the source, drain, and gate electrodes, which causes hydrogen to diffuse to the center of the channel. Here, a novel physical model of the capacitance–voltage (C–V) electrical property changes under ambient moisture is proposed, based on the early appearance of abnormalities in the C–V measurements. The electrolysis of water caused by the tip electric field and electrical abnormalities caused by hydrogen diffusion into the a-IGZO active layer are explained by this model. A secondary-ion mass spectrometry analysis shows that hydrogen content in the channel generally increases under NBS in ambient moisture. The degradation behavior due to moisture in a-IGZO is clarified. Thus, inhibiting the tip electric field may benefit future flexible-display and gas-sensing applications.

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Section: Experimental Devicesmentioning

confidence: 99%

Section: ■ Experimental Devicesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of the Capacitance–Voltage Electrical Characteristics of Thin-Film Transistors Caused by Hydrogen Diffusion under Negative Bias Stress in a Moist Environment

Chen

Kuo

Chang

et al. 2019

ACS Appl. Mater. Interfaces

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“…99–101 Especially in the study by Chen et al , a cyclical low-temperature annealing process was employed to alleviate the NBIS-induced instability of the a-IGZO TFT. 102 The cyclical annealing process in O 2 ambient condition at 220 °C is composed of an alternating heating process progressed at 220 °C for 3 min followed by 1 min cooling period (Fig. 11(a)).…”

Section: Stress Induced By Illuminationmentioning

confidence: 96%

Enhancement of electrical stability of metal oxide thin-film transistors against various stresses

Kim

2023

J. Mater. Chem. C

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“…Substantial improvements in the electrical performance and bias stress stability of oxide TFTs have been achieved based on the identification of the defect degradation mechanisms, including ambient interactions, charge trapping, and creation of deep defect states. − The dynamic interactions between the exposed back channel and atmosphere can be prevented by choosing an appropriate passivation layer, while the trapped charge carriers can be reduced by annealing. − However, the intrinsic subgap states related to oxygen vacancies (V O ), i.e., shallow donor states near the conduction band minimum (CBM) and deep donor states above the valence band maximum (VBM), are hardly to be eliminated by simple annealing or passivation, which capture electrons/photoexcited holes and incur threshold voltage ( V th ) shifts. , Preferably, extrinsic doping and the bilayer-channel structure are two of the most efficient channel engineering techniques in resolving the bias stress instability and electrical performance degradation issues. The incorporation of defect binders such as Hf or N can efficiently suppress the formation of V O defects and enhance the bias stress stability. − However, such dopants also serve as electron suppressors, which in turn degrade the transporting properties.…”

Section: Introductionmentioning

confidence: 99%

Graded Channel Junctionless InGaZnO Thin-Film Transistors with Both High Transporting Properties and Good Bias Stress Stability

Liu

Guo

Yang

et al. 2020

ACS Appl. Mater. Interfaces

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InGaZnO (IGZO) is currently the most prominent oxide semiconductor complement to low-temperature polysilicon for thin-film transistor (TFT) applications in flat panel displays. However, the compromised transport performance and bias stress instability are critical issues inhibiting its application in ultrahigh-resolution optoelectronic displays. Here, we report the fabrication of graded channel junctionless IGZO:O|N TFTs with both high transporting properties and good bias stress stability by systematic manipulation of oxygen vacancy (V O ) defects through sequential O antidoping and O/N codoping of the continuous IGZO framework. The transporting properties and bias stress stability of the graded channel IGZO:O|N TFTs, which exhibited high field-effect mobilities close to 100 cm 2 V −1 s −1 , negligible performance degradations, and trivial threshold voltage shifts against gate bias stress and photobias stress, are simultaneously improved compared to those of the controlled single-channel uniformly doped IGZO:O TFTs, IGZO:N TFTs, and double-channel barrier-confined IGZO:O/IGZO:N TFTs. The synergistic improvements are attributed to the sequential mobility and stability enhancement effects of O antidoping and O/N codoping where triple saturation currents are induced by O antidoping of the front-channel regime while the trapped electrons and photoexcited holes in the back-channel bulk and surface regions are suppressed by O/N codoping. More importantly, fast accumulation and barrier-free full depletion are rationally realized by eliminating the junction interface within the graded channel layer. Our observation identifies that graded channel doping could be a powerful way to synergistically boost up the transport performance and bias stress stability of oxide TFTs for new-generation ultrahigh-definition display applications.

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Cyclical Annealing Technique To Enhance Reliability of Amorphous Metal Oxide Thin Film Transistors

Cited by 20 publications

References 18 publications

Investigation of the Capacitance–Voltage Electrical Characteristics of Thin-Film Transistors Caused by Hydrogen Diffusion under Negative Bias Stress in a Moist Environment

Investigation of the Capacitance–Voltage Electrical Characteristics of Thin-Film Transistors Caused by Hydrogen Diffusion under Negative Bias Stress in a Moist Environment

Enhancement of electrical stability of metal oxide thin-film transistors against various stresses

Graded Channel Junctionless InGaZnO Thin-Film Transistors with Both High Transporting Properties and Good Bias Stress Stability

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