High Mobility Thin Film Transistors Fabricated on a Plastic Substrate at a Processing Temperature of 110°C

Gosain, Dharam Pal; Noguchi, Takashi; Usui, S.

doi:10.1143/jjap.39.l179

Cited by 111 publications

(69 citation statements)

References 3 publications

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“…Ultra low temperature polysilicon (ULTPS) processes are being developed to bring the process temperature down to 150 C (Theiss et al 1998;Gosain et al 2000). Both n-channel and p-channel TFTs with high mobilities and adequate threshold voltage have been made with ULTPS on glass, and with slightly lower but adequate mobilities on plastic; however, on/off ratios are of order 10 5 (Wickboldt et al 2003;Lemmi 2004).…”

Section: Tft Requirementsmentioning

confidence: 99%

OLED Displays on Plastic

Hildner

2005

Flexible Flat Panel Displays

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Section: Tft Requirementsmentioning

confidence: 99%

OLED Displays on Plastic

Hildner

2005

Flexible Flat Panel Displays

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“…A much higher performance of poly-Si TFTs is currently strongly required for the advanced flat panel display. As a flexible substrate, various TFTs on plastic boards, such as poly-imide and polyether-sulphone, or metal foils such as tungsten, thin stainless steel, or thinner glass, have been reported to date [2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Low-resistance phosphorus-doped Si films through blue laser diode annealing

Noguchi

Okada

2014

Journal of Information Display

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The effect of activated annealing on Si films using a new semiconductor blue laser was studied for application to the thin-film transistor (TFT) system on a panel. As a result of the blue laser diode annealing of the continuous-wave (CW) scanning mode at 500 mm/s for 50-nm-thick heavily phosphorus-doped Si films, drastic crystallization occurred while maintaining the surface's smoothness. By irradiating the laser power between 5 and 8 W for chemical vapour deposition films, the grain size was successively controlled by forming micrograins to large grains as well as to anisotropic long crystal grains. Correspondingly, the resistivity decreased depending on the increase in the electron mobility while the high carrier concentration values were retained for the various grained structures. The dopant activation rate was estimated to be 100% in the Si network in spite of the polycrystalline phase. The heavily doped Si film is expected to be applied to electrodes in high-performance TFTs as an advanced low-temperature polysilicon process on glass or flexible plastic sheets.

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“…In recent years, several studies have been conducted in order to achieve further low-temperature fabrication of poly-Si TFTs for the use of flexible plastic substrates. [7][8][9][10][11] Poly-Si thin films are generally formed by excimer laser annealing (ELA) using a-Si films on the glass substrate as a starting material. 1 However, laser crystallized poly-Si films still contain a huge amount of electrical defects and these electrical defects degrade the device performance.…”

mentioning

confidence: 99%

Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

Machida

Horita

Ishikawa

et al. 2012

Applied Physics Letters

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We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 lm, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films. Thin film transistors (TFTs) have been generally used for pixel switching devices of active matrix-flat panel displays such as liquid crystal displays and organic light emitting diode displays. In particular, the polycrystalline silicon (polySi) TFT has greater field-effect mobility (>50 cm 2 /V s) [1][2][3][4] than other channel materials such as amorphous silicon (a-Si), oxide, and organic (<10 cm 2 /V s), and the p-channel TFT can be fabricated by using poly-Si because of its high hole mobility.5 Thus, the poly-Si has the applicability not only to the high-performance pixel switching devices but also to the driver circuit or memory, that is, the system-on-panel display 6 can be realized. In recent years, several studies have been conducted in order to achieve further low-temperature fabrication of poly-Si TFTs for the use of flexible plastic substrates.7-11 Poly-Si thin films are generally formed by excimer laser annealing (ELA) using a-Si films on the glass substrate as a starting material.1 However, laser crystallized poly-Si films still contain a huge amount of electrical defects and these electrical defects degrade the device performance.12,13 Inactivation treatment of electrical defects such as hydrogenation by forming gas annealing (FGA) is usually conducted after crystallization, but this process needs substrate temperature around 400 C 14 and this is too high to use the plastic substrates because the glass transition temperature of typical plastic films such as polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) is lower than 160 C. Therefore, low-temperature annealing technique for the inactivation treatment is needed to realize poly-Si TFT fabrication on the plastic substrates. Here, we propose an underwater laser annealing (WLA): a laser annealing technique for low-temperature fabrication of poly-Si TFTs. We think that WLA could achieve low-temperature crystallization because of the cooling effect of the sample surface by additional thermal diffusion to flowing water. Moreover, it is expected that WLA has a capability for inactivation of electrical defects at the same time as crystallization. After pulse laser irradiation in water, a water vapor layer is generated on the Si surface where this water vapor contains some active species such as hydrogen, oxygen, and hydroxyl. H 2 O molecules will be chemically dissociated by heat energy, and electric...

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High Mobility Thin Film Transistors Fabricated on a Plastic Substrate at a Processing Temperature of 110°C

Cited by 111 publications

References 3 publications

OLED Displays on Plastic

OLED Displays on Plastic

Low-resistance phosphorus-doped Si films through blue laser diode annealing

Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

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