Total Subgap Range Density of States-Based Analysis of the Effect of Oxygen Flow Rate on the Bias Stress Instabilities in a-IGZO TFTs

Yang, Ga Won; Park, Jingyu; Kim, Changwook; Kim, Dong Myong; Choi, Sung-Jin; Bae, Jong-Ho; Cho, Il Hwan; Kim, Dae Hwan

doi:10.1109/ted.2021.3130219

Cited by 21 publications

(15 citation statements)

References 54 publications

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“…Consistently with 22 , this indicates that the In * -M probability of bond formation increases as the carrier concentration increases. In addition, g TA and g Vo2+ just below the E C [23][24][25] are relatively low in the HP sample case, which is consistent with that the SS of the HP sample is lower than that of the STD sample (Fig. 2b).…”

Section: Subgap Dos Extractionsupporting

confidence: 83%

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression

Kim

Choi

et al. 2022

Sci Rep

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Amorphous oxide semiconductor (AOS) field-effect transistors (FETs) have been integrated with complementary metal-oxide-semiconductor (CMOS) circuitry in the back end of line (BEOL) CMOS process; they are promising devices creating new and various functionalities. Therefore, it is urgent to understand the physics determining their scalability and establish a physics-based model for a robust device design of AOS BEOL FETs. However, the advantage emphasized to date has been mainly an ultralow leakage current of these devices. A device modeling that comprehensively optimizes the threshold voltage (VT), the short-channel effect (SCE), the subthreshold swing (SS), and the field-effect mobility (µFE) of short-channel AOS FETs has been rarely reported. In this study, the device modeling of two-steps oxygen anneal-based submicron indium-gallium-zinc-oxide (IGZO) BEOL FET enabling short-channel effects suppression is proposed and experimentally demonstrated. Both the process parameters determining the SCE and the device physics related to the SCE are elucidated through our modeling and a technology computer-aided design (TCAD) simulation. In addition, the procedure of extracting the model parameters is concretely supplied. Noticeably, the proposed device model and simulation framework reproduce all of the measured current–voltage (I–V), VT roll-off, and drain-induced barrier lowering (DIBL) characteristics according to the changes in the oxygen (O) partial pressure during the deposition of IGZO film, device structure, and channel length. Moreover, the results of an analysis based on the proposed model and the extracted parameters indicate that the SCE of submicron AOS FETs is effectively suppressed when the locally high oxygen-concentration region is used. Applying the two-step oxygen annealing to the double-gate (DG) FET can form this region, the beneficial effect of which is also proven through experimental results; the immunity to SCE is improved as the O-content controlled according to the partial O pressure during oxygen annealing increases. Furthermore, it is found that the essential factors in the device optimization are the subgap density of states (DOS), the oxygen content-dependent diffusion length of either the oxygen vacancy (VO) or O, and the separation between the top-gate edge and the source-drain contact hole. Our modeling and simulation results make it feasible to comprehensively optimize the device characteristic parameters, such as VT, SCE, SS, and µFE, of the submicron AOS BEOL FETs by independently controlling the lateral profile of the concentrations of VO and O in two-step oxygen anneal process.

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Section: Subgap Dos Extractionsupporting

confidence: 83%

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression

Kim

Choi

et al. 2022

Sci Rep

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“…As shown in Table 4, the increase in PO for OD-IGZO showed stronger influences on the total Δne than that for OR-IGZO, which is also consistent with the measurement results shown in Figure 2. It is well known that the electron concentration closely relates oxygen vacancies and the other defects in a-IGZO [27,28], so the simulation results shown in Figure 6 also reflected how the defects (espe- After the DSCL-TFTs were illuminated by the 380 nm UV light for 600 s, the electron concentration n e increased to n e . The variation of the electron concentration (∆n e = n e − n e ) could microscopically denote the UV light sensing abilities of the DSCL-TFTs.…”

Section: Parameter Od-igzo Or-igzo Descriptionmentioning

confidence: 77%

“…From the UVS characterization results shown in Figure 3, we could assume that band-to-band electron excitation would be nearly the same for all the devices in this study. On the one hand, the net photogenerated electron concentration (∆n e ) decreased with P O for DSCL increasing and the photogenerated V O 2+ were believed to play an important role in UV light sensing [22,28]. Therefore, we could suppose that the P O increase during the DSCL depositions might reduce the concentration of photogenerated V O 2+ and result in smaller ∆n e in the channel layers.…”

Section: Discussionmentioning

confidence: 99%

“…As shown in Table 4, the increase in P O for OD-IGZO showed stronger influences on the total ∆n e than that for OR-IGZO, which is also consistent with the measurement results shown in Figure 2. It is well known that the electron concentration closely relates oxygen vacancies and the other defects in a-IGZO [27,28], so the simulation results shown in Figure 6 According to all the experimental data and simulation results, we made a deeper discussion on the PO effect for DSCL-TFT UV light response. From the UVS characterization results shown in Figure 3, we could assume that band-to-band electron excitation would be nearly the same for all the devices in this study.…”

Section: Parameter Od-igzo Or-igzo Descriptionmentioning

confidence: 99%

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Amorphous InGaZnO Thin-Film Transistors with Double-Stacked Channel Layers for Ultraviolet Light Detection

et al. 2022

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Amorphous InGaZnO thin film transistors (a-IGZO TFTs) with double-stacked channel layers (DSCL) were quite fit for ultraviolet (UV) light detection, where the best DSCL was prepared by the depositions of oxygen-rich (OR) IGZO followed by the oxygen-deficient (OD) IGZO films. We investigated the influences of oxygen partial pressure (PO) for DSCL-TFTs on their sensing abilities by experiments as well as Technology Computer Aided Design (TCAD) simulations. With the increase in PO values for the DSCL depositions, the sensing parameters, including photogenerated current (Iphoto), sensitivity (S), responsivity (R), and detectivity (D*) of the corresponding TFTs, apparently degraded. Compared with PO variations for the OR-IGZO films, those for the OD-IGZO depositions more strongly influenced the sensing performances of the DSCL-TFT UV light detectors. The TCAD simulations showed that the variations of the electron concentrations (or oxygen vacancy (VO) density) with PO values under UV light illuminations might account for these experimental results. Finally, some design guidelines for DSCL-TFT UV light detectors were proposed, which might benefit the potential applications of these novel semiconductor devices.

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“…from 0.57 to 0.75 V. Also, the average SS is improved by 50% in the TG FeFETs with the ITO-IGZO heterojunction channel. The poor SS in the n-channel transistor has been attributed to the deep-level defects [43]. Here, the ITO layer contributes to deep-level defect passivation.…”

Section: A Channel Defects Self-compensation Effect On Tg Ito-igzo Fe...mentioning

confidence: 99%

High-Performance Top-Gated and Double-Gated Oxide–Semiconductor Ferroelectric Field-Effect Transistor Enabled by Channel Defect Self-Compensation Effect

Chen

Hooda

Fang

et al. 2023

IEEE Trans. Electron Devices

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In this article, we demonstrate a low-thermal budget defect-engineered process to achieve top-gated (TG) oxide-semiconductor ferroelectric field-effect transistors (FeFETs). The demonstrated TG FeFETs, with the channel length scaled down to 40 nm, exhibit a highly stabilized ferroelectric memory window (MW) of 2 V and a high current ON/OFF ratio of 10 6 . This is achieved by an engineered InGaZnO x (IGZO) and InSnO x (ITO) heterojunction channel that produces the defect self-compensation effect to passivate the intrinsic oxygen-deficient defects, existing in the indium-gallium-zinc-oxide (IGZO) channel interface and bulk. Effective interface/bulk defects passivation with good control of defect-induced channel carrier concentration has been notoriously difficult to achieve. Hence, realizing performant TG oxide-based FeFETs with back-end-of-line (BEOL) thermal budget constraints remains a fundamental challenge. Our study shows that heterojunction channel engineering on FETs and FeFETs can be a reliable solution to overcome this challenge. With such a technique, we can now enable double-gated (DG) ITO-IGZO FeFET and FETs. Such devices can enable BEOL-compatible reconfigurable nonvolatile logic switches that provide extremely low offstate leakage, high switch conductance ratio, and memory read-write disturb-free features.

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Total Subgap Range Density of States-Based Analysis of the Effect of Oxygen Flow Rate on the Bias Stress Instabilities in a-IGZO TFTs

Cited by 21 publications

References 54 publications

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression

Amorphous InGaZnO Thin-Film Transistors with Double-Stacked Channel Layers for Ultraviolet Light Detection

High-Performance Top-Gated and Double-Gated Oxide–Semiconductor Ferroelectric Field-Effect Transistor Enabled by Channel Defect Self-Compensation Effect

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