Mechanism of Plasma Hydrogenation of Polysilicon Thin Film Transistors

Mitra, U.; Rossi, Barbara; Khan, Babar A.

doi:10.1149/1.2085426

Cited by 39 publications

(6 citation statements)

References 2 publications

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“…Reduction of defects by post laser annealing is important for good TFT characteristics. Plasma hydrogenation has been widely investigated to terminate silicon dangling bonds with hydrogen atoms and reduce the density of electrically active defects [22][23][24][25]. Oxygen plasma treatment is also effective to reduce the density of defects [26].…”

Section: Structural and Electrical Propertiesmentioning

confidence: 99%

Laser crystallization for large-area electronics

Sameshima

2009

Appl. Phys. A

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Laser crystallization is reviewed for the purpose of fabrication of polycrystalline silicon thin film transistors (poly-Si TFTs). Laser-induced rapid heating is important for formation of crystalline films with a low thermal budget. Reduction of electrically active defects located at grain boundaries is essential for improving electrical properties of poly-Si films and achieving poly-Si TFTs with high performances. The internal film stress is attractive to increase the carrier mobility. Recent developments in laser crystallization methods with pulsed and continuous-wave lasers are also reviewed. Control of heat flow results in crystalline grain growth in the lateral direction, which is important for fabrication of large crystalline grains. We also report an annealing method using a high-power infrared semiconductor laser. High-power lasers will be attractive for rapid formation of crystalline films over a large area and activation of silicon with impurity atoms.

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Section: Structural and Electrical Propertiesmentioning

confidence: 99%

Laser crystallization for large-area electronics

Sameshima

2009

Appl. Phys. A

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“…Hydrogenation has been widely used to terminate defects in poly-Si, such as dangling bonds. [34][35][36][37][38] Plasma hydrogenation is especially effective in improving the electrical properties of laser-crystallized silicon films. Hydrogen atoms were effectively incorporated into the silicon films and terminated the dangling bonds.…”

Section: Defect Passivation and Sio 2 /Si Interface Formationmentioning

confidence: 99%

Progress in fabrication technologies of polycrystalline-silicon thin-film transistors at low temperatures

Sameshima

2005

J. Soc. Inf. Display

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Abstract— The development of fabrication processes for polycrystalline‐silicon thin‐film transistors (poly‐Si TFTs) at low temperatures will be discussed. Rapid crystallization of silicon films through laser‐induced melt regrowth has the advantage of having a low thermal budget. Solid‐phase crystallization techniques have also been improved for low‐temperature processing. Passivation of the SiO2/Si interface and crystalline grain boundaries is important in achieving high‐carrier‐transport properties. Oxygen‐plasma and H2O‐vapor heat treatments are proposed for the effective reduction of the density of defect states. TFTs with high performances will be reported.

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“…The grain boundaries in the aluminum cap region were clearly seen after Secco etching. However, the grain boundaries near the aluminumcapped edge were ambiguous because they were passivated by hydrogen lateral diffusion, 16 thereby reducing the etching rate around the grain boundaries. This result implies that lateral diffusion of hydrogen may lead to a lack of uniformity in the passivation of grain boundaries throughout the channel region.…”

Section: A Features Of the Excimer-laser-crystallized Poly-si Filmsmentioning

confidence: 99%

Effects of grain boundaries on performance and hot-carrier reliability of excimer-laser annealed polycrystalline silicon thin film transistors

Chen

Yeh

Lou

2004

Journal of Applied Physics

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Erratum: "Effect of excimer laser annealing on the structural and electrical properties of polycrystalline silicon thin-film transistors" [J.Electrical and noise properties of thin-film transistors on very thin excimer laser annealed polycrystalline silicon films Appl.This work examines the effects of grain boundaries on the performance and hot-carrier reliability of excimer-laser-annealed polycrystalline silicon thin film transistors ͑poly-Si TFTs͒ before and after NH 3 plasma treatment. Self-aligned poly-Si TFTs, whose channel regions include a 150 nm thick laser-crystallized poly-Si layer with small grains and a 100 nm thick layer with large grains, are fabricated. Other TFTs, with large grains throughout their channels, are fabricated nearby for comparison. The trapping of electrons at grain boundaries in the drain junction creates strong local electric fields that boost the leakage current, cause the threshold voltage to decline as the drain bias increases, enhance the kink effect in the output characteristics, and degrade the hot-carrier reliability of devices. When static hot-carrier stress is applied to nonhydrogenated poly-Si TFTs for less than 10 4 s at V GS ϭ10 V and V DS ϭ20 V, hot holes are injected into the gate oxide at the same time trap states are created in the drain junction. The screening effect is observed when the same stress is applied to devices that have many grain boundaries in their drain junctions. NH 3 plasma treatment prevents the trapping of electrons at grain boundaries. The performance of hydrogenated poly-Si TFTs improves, but the hot-carrier reliability of those TFTs with large grains in their drain junctions degrades. The hydrogenation causes a trade-off between the electrical characteristics and the hot-carrier reliability, and introduces irregular humps in the subthreshold region.

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Mechanism of Plasma Hydrogenation of Polysilicon Thin Film Transistors

Cited by 39 publications

References 2 publications

Laser crystallization for large-area electronics

Laser crystallization for large-area electronics

Progress in fabrication technologies of polycrystalline-silicon thin-film transistors at low temperatures

Effects of grain boundaries on performance and hot-carrier reliability of excimer-laser annealed polycrystalline silicon thin film transistors

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