Advanced excimer-laser crystallization process for single-crystalline thin film transistors

Ishihara, Ryoichi; Wilt, Paul C. van der; Dijk, Barry D. van; Burtsev, Artyom; Metselaar, J.W.; Beenakker, C.I.M.

doi:10.1016/s0040-6090(02)01250-6

Cited by 50 publications

(43 citation statements)

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“…We considered it is necessary to use a laser with a wavelength shorter than 400 nm, for the laser to be absorbed by the IZO film since IZO has a wide band gap (higher than 3 eV). 14 We used an XeCl excimer laser with a sufficiently short wavelength of 308 nm (photon energy: 4.02 eV) 15,16 and investigated the effects of the ELA process on the IZO TFT characteristics and film properties.A thermally oxidized SiO 2 film of 100 nm thickness was formed on a highly doped p-type silicon wafer (<0.002 X cm) as a gate insulator. IZO films with a thickness of 50 nm were deposited by RF magnetron sputtering on SiO 2 /Si wafers with a gas mixture of argon and oxygen at room temperature.…”

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Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

Fujii

Ishikawa

Ishihara

et al. 2013

Applied Physics Letters

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In this study, we successfully achieved a relatively high field-effect mobility of 37.7 cm 2 /Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50 C according to thermal calculation. Our analysis revealed that high-energy irradiation in ELA produced a mixed phase of InZnO and SiO 2 , leading to the deterioration of TFT characteristics. Oxide semiconductor films deposited by sputtering have recently attracted considerable attention in the fields of transparent and flexible electronics for next-generation displays, in comparison with conventional amorphous silicon-based materials. In particular, an In 2 O 3 -doped ZnO (IZO) thin film is widely recognized as a suitable oxide semiconductor since thin-films transistors (TFTs) with that material in the channel layer yield a higher field-effect mobility than amorphous InGaZnO (a-IGZO) TFTs. [1][2][3] In the case of the IZO film, the amorphous phase generally provides a high conductivity of about 400 X À1 cm À1 , which is much higher than the conductivity suitable for the TFT's channel layer. 4,5 The conductivity of this material can possibly be reduced by a thermal annealing process. 6,7 In previous reports, thermal annealing with a relatively high temperature of about 300 C has been proposed to produce operative IZO TFTs. 8,9 However, such a high-temperature process in postannealing limits the choice for plastic flexible substrates. The excimer laser annealing (ELA) process with short pulses has been widely utilized to achieve a low processing temperature to produce a polycrystalline silicon thin film on a glass substrate. 10 This technique has also been utilized for oxide-semiconductor materials. Nakata et al. reported the fabrication of a-IGZO TFTs by ELA process, which acted as a postannealing process, and the improvement of the TFTs characteristics by ELA, 11 suggesting that the ELA process is also a promising technique for improving the characteristics of oxide-semiconductor devices. In this study, we focused on an IZO TFT with a higher field-effect mobility than an a-IGZO TFT. We assumed that an ELA process crystallizes IZO with nanograins easily since this material has a lower crystallization temperature than a-IGZO 12,13 and that an IZO film composed of nanograins has better characteristics than a noncrystallized IZO TFT since carrier scattering is suppressed in the disordered film. We considered it is necessary to use a laser with a wavelength shorter than 400 nm, for the laser to be absorbed by the IZO film since IZO has a wide band gap (higher than 3 eV). 14 We used an XeCl excimer laser with a sufficiently short wavelength of 308 nm (photon energy: 4.02 eV) 15,16 and investigated the effects of the ELA process on the IZO TFT characteristics and film properties.A thermally oxidized SiO 2 film of 100 nm thickness was formed on a highly doped p-type silicon wafer (<0.002 X cm) as a gate insulator. IZO films with...

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Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

Fujii

Ishikawa

Ishihara

et al. 2013

Applied Physics Letters

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“…To fabricated Si devices with the printing process, a low-cost process due to the absence of vacuum and lithography and could be used for the flexible devices, Shimoda, et al, have reported the fabrication of poly-Si TFTs from spin-coated liquid-Si material, resulting in the carrier mobility of 108 cm 2 /Vs for electrons. [4] To improve the carrier mobility, our group has reported the approach of fabricating single-grain Si TFTs from spin-coated liquid Si, [5], on the single Si grains crystallized using the excimer laser with the µ-Czochralski process [6]. The devices were with the carrier mobility of 391 cm2/Vs and 111 cm2/Vs for electrons and holes, respectively.…”

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(Invited) Single-Grain Si Tfts Fabricated on a Precursor from Doctor-Blade Coated Liquid-Si

et al. 2014

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Printing is attractive for manufacturing flexible circuits. This manuscript presents our investigation of single-grain Si TFTs fabricated from printed liquid-Si, on a polyimide substrate with the maximum process temperature of 350 °C. The field-effect mobility is 460 cm2/Vs for electrons and 121 cm2/Vs for the holes. CMOS inverters were also fabricated. The devices function at the bending diameter of 3 mm. The device performance under the bending stress was discussed.

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“…[1][2][3][4][5][6] We have studied secondary grain growth as the crystal growth mechanism of poly-Siˆlm prepared by ELA. Secondary grain growth is the mechanism of enlargement of the poly-Si grain, which is larger than the thickness of theˆlm, caused by the movement of the grain boundary.…”

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Influence of Post Excimer Laser Annealing on Crystallinity of Precursor Polycrystalline Si Film Formed by Solid Phase Crystallization

et al. 2007

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Fig. 1 Relationship between tensile stress of poly-Siˆlm and energy density.Journal of the Vacuum Society of Japan Vol. 50, No. 8 (2007) The crystallinity of polycrystalline Si (poly-Si)ˆlm produced by the combined method of solid phase crystallization (SPC) followed by excimer laser annealing (ELA) or ELA followed by SPC is examined by observing the internal stress and the crystal defect. Tensile stress relaxation occurred when SPC was performed before or after ELA. The defect densities of poly-Sî lms recrystallized by ELA, ELA followed by SPC, and SPC followed by ELA decrease in this order.

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Advanced excimer-laser crystallization process for single-crystalline thin film transistors

Cited by 50 publications

References 18 publications

Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

(Invited) Single-Grain Si Tfts Fabricated on a Precursor from Doctor-Blade Coated Liquid-Si

Influence of Post Excimer Laser Annealing on Crystallinity of Precursor Polycrystalline Si Film Formed by Solid Phase Crystallization

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