The characteristics of fluorinated polycrystalline silicon oxides and thin film transistors by CF4 plasma treatment

Kao, Chiang; Lai, Chao−Sung; Sung, W. H.; Lee, C.H.

doi:10.1016/j.tsf.2010.09.001

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…Fan et al 45 carried out N 2 O plasma treatment on the SiO 2 dielectric in pentacene TFTs, the effective trap state density reduced from 1.61 × 10 13 cm −2 to 1.1 × 10 13 cm −2 . In the research of Kao et al, 46 they used CF 4 plasma treatment on the SiO 2 dielectric in poly-silicon TFTs, the effective trap state density also reduced from 6.32 × 10 12 cm −2 to 5.56 × 10 12 cm −2 . In this study, the N 2 O plasma-treated TFT device reveals that a low effective trap state density (N t = 7.34 × 10 11 cm −2 ) as compared to either the non-treated device (N t = 1.35 × 10 12 cm −2 ) or the TFTs treated with Ar or O 2 plasma.…”

Section: Resultsmentioning

confidence: 99%

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Chen

Jeng

2013

ECS J. Solid State Sci. Technol.

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ZnO thin-film transistors (TFTs) using MgO dielectrics achieve a high field-effect mobility of around 50 cm 2 /Vs. Plasma treatments with different gases applied on the MgO dielectric surface will amend the TFT's electrical stability and X-ray photoelectron spectroscopy analysis is done nearby the ZnO/MgO interface to study the change of oxygen chemical bonding states. The results show that MgO dielectric without plasma treatment causes the threshold voltage shift of the transistor, which may be attributed to the migration of oxygen ion toward the ZnO/MgO interface to induce the generation of oxygen vacancies in ZnO active layer when devices are under positive gate bias stress. This instability behavior can be eliminated with N 2 O plasma treatment on MgO. N 2 O plasma treatment inhibits the generation of oxygen vacancies in ZnO against gate bias stress thus reduces the effective trap state density in the subgap of ZnO and thereby enhances the TFT's stability. The detailed scenario for the plasma treatment effect is explored to conclude its mechanism on improving the electrical stability.ZnO is a oxide semiconductor which can be applied to many different electronic devices, such as transparent conducting oxide (TCO), 1,2 light emitting diodes (LED) 3 or resistance random access memory (RRAM). 4,5 Especially, the ZnO-based TFTs 6-11 have attracted attention for application in flat panel display owing to their reasonable mobility and transparency in visible light region. For practical applications, the electrical stability of TFTs will be an important issue to overcome. Bias stress test is a general method to determine the electrical stability of the device by tracing the transfer characteristic (I D -V G curves) of the transistor with giving a constant bias in gate electrode for a period of time. The threshold voltage shift ( V TH ) under gate bias stress is a crucial parameter to determine the electrical stability of TFT devices in active matrix liquid crystal display applications since the bias stress-induced threshold voltage shift leads to a change in the individual pixel brightness. At the same time, V TH that is sensitive to light illumination will limit the TFT application to the next generation of transparent electronics because the exposure of switching TFTs to backlight or ambient light would be inevitable during the operation of the electronics such as display panel. The degradation behaviors of ZnO-based TFTs have been investigated by many previous studies. 12-17 They indicated that the V TH under bias stress or light illumination can be attributed to the charge trapping in the gate insulator or in the active layer/insulator interface, 13-15 and oxygen or water absorption/desorption at back channel. 16,17 In a-Si:H TFTs, the charge trapping sites can be eliminated through an annealing of the a-Si. However, high temperature annealing of ZnO 18 is not suitable for glass substrates owing to their low softening/melting temperatures. 19 An alternative solution for reducing the trapping sites is adding an el...

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Section: Resultsmentioning

confidence: 99%

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Chen

Jeng

2013

ECS J. Solid State Sci. Technol.

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“…Since an appropriate amount of fluorine added can bond fluorine atoms to dangling bonds and displace extra oxygen atoms near the high-k/Si interface, the incorporation of CF 4 plasma treatment can cause the high-k Ta 2 O 5 gate dielectrics to have better electrical performance and material properties. [7][8][9][10][11] In this research, the effect of CF 4 plasma treatment of various times with annealing on high-k Ta 2 O 5 polyoxide capacitors has been investigated using electrical characterization techniques, including EOT, current density-electric field (J-E) characteristics, gate voltage shift versus time, and Weibull plots. 12,13) The electrical behavior changes have been correlated with the results of material analyses, including X-ray diffraction (XRD) analysis, atomic force microscopy (AFM), and secondary ion mass spectroscopy (SIMS).…”

Section: Introductionmentioning

confidence: 99%

Ta₂O₅ Polycrystalline Silicon Capacitors with CF₄ Plasma Treatment

Kao

Chen

2012

Jpn. J. Appl. Phys.

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In this research, the effects of CF4 plasma treatment with post annealing on the electrical characteristics and material properties of Ta2O5 dielectrics were determined. The dielectric performance characteristics of samples under different treatment conditions were measured using equivalent oxide thickness (EOT), current density–electric field (J–E) characteristics, gate voltage shift versus time, and Weibull plots. In addition, X-ray diffraction (XRD) analysis provided insight into the changes in crystalline structure, atomic force microscopy (AFM) measurements visualized the surface roughness, and secondary ion mass spectroscopy (SIMS) revealed the distribution of fluorine ions inside the dielectric samples. Findings indicate that dielectric performance can be significantly improved by CF4 plasma treatment for 1 min with post annealing at 800 °C. The improvements in electrical characteristics were caused by the appropriate incorporation of the fluorine atoms and the removal of the dangling bonds and traps. The Ta2O5 dielectric incorporated with appropriate CF4 plasma and annealing treatments shows great promise for future generation of nonvolatile memory applications.

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CF4 plasma effect combined with rapid thermal annealing for high-k Er2O3 dielectrics

Kao¹,

Fan²,

Cheng³

et al. 2012

Thin Solid Films

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The characteristics of fluorinated polycrystalline silicon oxides and thin film transistors by CF4 plasma treatment

Cited by 4 publications

References 17 publications

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Ta₂O₅ Polycrystalline Silicon Capacitors with CF₄ Plasma Treatment

CF4 plasma effect combined with rapid thermal annealing for high-k Er2O3 dielectrics

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The characteristics of fluorinated polycrystalline silicon oxides and thin film transistors by CF4 plasma treatment

Cited by 4 publications

References 17 publications

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N2O Plasma Treated MgO Gate Dielectrics

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N2O Plasma Treated MgO Gate Dielectrics

Ta2O5 Polycrystalline Silicon Capacitors with CF4 Plasma Treatment

CF4 plasma effect combined with rapid thermal annealing for high-k Er2O3 dielectrics

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Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Suppression of Oxygen Vacancy and Enhancement in Bias Stress Stability of High-Mobility ZnO Thin-Film Transistors with N₂O Plasma Treated MgO Gate Dielectrics

Ta₂O₅ Polycrystalline Silicon Capacitors with CF₄ Plasma Treatment