Highly reliable passivation layer for <i>a</i>-InGaZnO thin-film transistors fabricated using polysilsesquioxane

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Yamazaki, Haruka; Nonaka, Toshiaki; Uraoka, Yukiharu

doi:10.1557/opl.2014.118

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…The enhanced device performance of a TFT with a thicker IGZO film can also be explained by the reduced DOS in the IGZO film. It is worth noting that device performances of passivated IGZO TFTs with O 3 -ALD Y 2 O 3 in the current study are comparable with previous reports, ,,− together with the effective passivation of the defect states at the back-channel surface as compared to other passivation layers reported elsewhere. ,,− Recently, Xie et al reported almost negligible V th shift after 2500 s of the NBIS test with 380 nm wavelength light with molybdenum-doped ZnO (MZO) as a UV shield layer and nitrogen-doped IGZO channel (IGZO:N). However, the degradation of device performance was observed with MZO-passivated IGZO:N TFTs as compared to unpassivated IGZO:N TFTs .…”

Section: Resultssupporting

confidence: 89%

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone

Jung

Kim

Park

et al. 2018

ACS Appl. Mater. Interfaces

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We report the effect of YO passivation by atomic layer deposition (ALD) using various oxidants, such as HO, O plasma, and O, on In-Ga-Zn-O thin-film transistors (IGZO TFTs). A large negative shift in the threshold voltage (V) was observed in the case of the TFT subjected to the HO-ALD YO process; this shift was caused by a donor effect of negatively charged chemisorbed HO molecules. In addition, degradation of the IGZO TFT device performance after the O plasma-ALD YO process (field-effect mobility (μ) = 8.7 cm/(V·s), subthreshold swing (SS) = 0.77 V/dec, and V = 3.7 V) was observed, which was attributed to plasma damage on the IGZO surface adversely affecting the stability of the TFT under light illumination. In contrast, the O-ALD YO process led to enhanced device stability under light illumination (ΔV = -1 V after 3 h of illumination) by passivating the subgap defect states in the IGZO surface region. In addition, TFTs with a thicker IGZO film (55 nm, which was the optimum thickness under the current investigation) showed more stable device performance than TFTs with a thinner IGZO film (30 nm) (ΔV = -0.4 V after 3 h of light illumination) by triggering the recombination of holes diffusing from the IGZO surface to the insulator-channel interface. Therefore, we envisioned that the O-ALD YO passivation layer suggested in this paper can improve the photostability of TFTs under light illumination.

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Section: Resultssupporting

confidence: 89%

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone

Jung

Kim

Park

et al. 2018

ACS Appl. Mater. Interfaces

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“…To contact the drain/source with electrical wiring, etching the passivation layer by RIE was performed, which affected the TFT's initial transfer characteristics [21]. Photosensitive material can form a contact hole through the passivation layer without RIE.…”

Section: Methodsmentioning

confidence: 99%

Fluorine incorporation in solution-processed poly-siloxane passivation for highly reliablea-InGaZnO thin-film transistors

Yoshida

Bermundo

Ishikawa

et al. 2018

J. Phys. D: Appl. Phys.

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We investigated a fluorine-containing polysiloxane (Poly-SX) passivation layer fabricated by solution process for amorphous InGaZnO (a-IGZO) thin-film transistors (TFT). This passivation layer greatly improved the stability of the a-IGZO device even after being subjected to positive bias stress (PBS) and negative bias stress (NBS). The mobility (µ) of TFTs passivated by fluorine-containing Poly-SX increased by 31%–56% (10.50–12.54 cm2 V−1 s−1) compared with TFTs passivated by non-fluorinated Poly-SX (8.04 cm2 V−1 s−1). Increasing the amount of fluorine additives led to a higher µ in passivated TFTs. Aside from enhancing the performance, these passivation layers could increase the reliability of a-IGZO TFTs under PBS and NBS with a minimal threshold voltage shift (ΔVth) of up to +0.2 V and −0.1 V, respectively. Additionally, all TFTs passivated by the fluorinated passivation materials did not exhibit a hump effect after NBS. We also showed that fluorinated photosensitive Poly-SX, which can be fabricated without any dry etching process, had an effective passivation property. In this report, we demonstrated the photolithography of Poly-SX, and electrical properties of Poly-SX passivated TFTs, and analyzed the state of the a-IGZO layer to show the large potential of Poly-SX as an effective solution-processed passivation material.

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“…[18][19][20][21] The use of organic passivation layers is one solution, given that organic passivation layers can be deposit at room temperature by a simple spin-coating or slot-coating processes, without inflicting plasma damage. [22][23][24] However, organic materials are not very good passivation layers because of their very high water vapor transmission rate (WVTR). In this work, we propose a fluorinated siloxane-based organic passivation layer.…”

mentioning

confidence: 99%

Thermal Stability Improvement of Back Channel Etched a-IGZO TFTs by Using Fluorinated Organic Passivation

Park

Mativenga

et al. 2018

ECS J. Solid State Sci. Technol.

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The effect of adding fluorine (F) to an organic passivation is investigated in back channel etched (BCE) amorphous-indium-galliumzinc-oxide (a-IGZO) thin-film transistors (TFTs). The organic passivation consists of propylene glycol monomethyl ether acetate (PGMEA), a polyhydroxy styrene (PHS) resin, a silane coupling agent, and the F additive. From thermogravimetric analysis (TGA), F concentration of 1wt% is found to be the optimum formulation of the organic passivation layer. A-IGZO TFTs fabricated with the fluorinated organic passivation exhibited better stability after thermal annealing at 300 • C compared to those without the fluorinated organic passivation. X-ray photoelectron spectroscopy (XPS) depth profiling reveals that components of the organic passivation diffuse into the underlying a-IGZO layer such that traces of C1s and Si2p could be detected at the bottom surface of the a-IGZO. Deconvolution of the O1s spectrum also indicated the reduction of oxygen vacancy (V O ) defects. It is assumed that F is responsible for the reduction of V O defects, which in turn leads to better thermal stability.

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Highly reliable passivation layer for a-InGaZnO thin-film transistors fabricated using polysilsesquioxane

Cited by 6 publications

References 17 publications

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone

Fluorine incorporation in solution-processed poly-siloxane passivation for highly reliablea-InGaZnO thin-film transistors

Thermal Stability Improvement of Back Channel Etched a-IGZO TFTs by Using Fluorinated Organic Passivation

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Highly reliable passivation layer for a-InGaZnO thin-film transistors fabricated using polysilsesquioxane

Cited by 6 publications

References 17 publications

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y2O3 with Ozone

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y2O3 with Ozone

Fluorine incorporation in solution-processed poly-siloxane passivation for highly reliablea-InGaZnO thin-film transistors

Thermal Stability Improvement of Back Channel Etched a-IGZO TFTs by Using Fluorinated Organic Passivation

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Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited Y₂O₃ with Ozone