Oxygen-related Reliability of Amorphous InGaZnO Thin Film Transistors

Yen, Chueh-Chuan; Tai, An-Hung; Liu, Yu-Chieh; Chen, Tsang-Long; Chou, Cheng-Hsu; Liu, C. W.

doi:10.1109/jeds.2020.2993018

Cited by 13 publications

(6 citation statements)

References 23 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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“…5) or via the shallow states (Blue arrow in Fig. 5) [14] during VGS sweeping. Since tunneling requires a similar energy level for both initial and final states to have a large tunneling probability, the tunneling via shallow states can be more effective [15].…”

Section: Room Temperature Resultsmentioning

confidence: 99%

Performance Improvement by Double-Layer a-IGZO TFTs With a Top Barrier

Chiu

Lee

et al. 2022

IEEE J. Electron Devices Soc.

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“…Nevertheless, the traditional hydrogenated amorphous silicon (a-Si:H) TFTs show low mobility (< 1 cm 2 /V-s) [3] and poor stability [4], making it difficult for advanced applications. In recent years, amorphous indium gallium zinc oxide (a-IGZO) has attracted much attention to be the promising channel material of TFTs for nextgeneration displays due to the high mobility (> 10 cm 2 /V-s), high on/off current ratio, good uniformity in large area, low process temperature (< 400 • C), and low manufacturing cost [5]- [8]. Up to now, the a-IGZO TFTs with several structures have been fabricated, such as a bottom gate structure with etch-stop layer [9], [10], a bottom gate structure with back-channel-etch (BCE) type [11], and a top-gate selfaligned (TG-SA) coplanar structure [12], [13].…”

Section: Introductionmentioning

confidence: 99%

Mobility Enhancement and Abnormal Humps in Top-Gate Self-Aligned Double-Layer Amorphous InGaZnO TFTs

Lee

Chiu

et al. 2022

IEEE J. Electron Devices Soc.

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The mobility enhancement and the positive bias stress of top-gate self-aligned TFTs using the a-IGZO channel with a front barrier are investigated. The a-IGZO front barrier can keep electrons in the a-IGZO channel away from the top-gate oxide to significantly enhance the electron mobility at the top gate operation. The parasitic channel induces a hump in the transfer characteristics. The positive bias stress shifts the hump to the negative voltage abnormally. The H 2 O in the polymer film on array layer is responsible for the abnormal shift. The H 2 O diffuses into the top-gate insulator and is electrolyzed to create H + , which forms a parasitic channel with a negative shift of threshold voltage, leading to the abnormal hump. The abnormal humps are increasingly significant with the increasing channel width and the decreasing channel length. The channel width dependence on positive bias stress is due to the inverse narrow width effect caused by the fringe electric field. The channel length dependence on positive bias stress is due to the H + diffusion toward the center of the parasitic channel from both the source and drain sides.INDEX TERMS Positive bias stress (PBS), a-IGZO, hump, polymer film on array (PFA).

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Oxygen-related Reliability of Amorphous InGaZnO Thin Film Transistors

Cited by 13 publications

References 23 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

Performance Improvement by Double-Layer a-IGZO TFTs With a Top Barrier

Mobility Enhancement and Abnormal Humps in Top-Gate Self-Aligned Double-Layer Amorphous InGaZnO TFTs

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