Performance of Poly-Si TFTs Fabricated by SELAX

Tai, Masayuki; Hatano, Mutsuko; Yamaguchi, Shinya; Noda, Takeshi; Park, Seong-kee; Shiba, T.; Ohkura, M.

doi:10.1109/ted.2004.828167

Cited by 58 publications

(32 citation statements)

References 11 publications

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“…Consequently, nonuniform and randomly distributed poly-Si grains will result in large variation of TFT performance when the laser energy density is controlled in the SLG regime, particularly, for smalldimension TFTs [13], [14]. Thus, many laser crystallization methods have been proposed to produce large grains with uniform grain size distribution, including sequential lateral solidification [15], the grain filters method [16], capping the reflective or antireflective layer [17], phase-modulated ELC [18], dual-beam excimer laser annealing (ELA) [19], double-pulsed laser annealing [20], selectively floating a-Si active layer [21], continuous-wave laser lateral crystallization [22], selectively enlarging laser crystallization [23], and so on. However, some of them are not readily attached to existing ELA systems or are problematic for circuit layout due to the anisotropy of the grain boundary spacing.…”

Section: Introductionmentioning

confidence: 99%

High-Performance Short-Channel Double-Gate Low-Temperature Polysilicon Thin-Film Transistors Using Excimer Laser Crystallization

Tsai

Wei

Lee

et al. 2007

IEEE Electron Device Lett.

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In this letter, high-performance low-temperature polysilicon thin-film transistors (TFTs) with double-gate (DG) structure and controlled lateral grain growth have been demonstrated by excimer laser crystallization. Via a proper excimer laser condition, along with the a-Si step height beside the bottom gate, a superlateral growth of Si was formed in the channel length plateau. Therefore, the DG TFTs with lateral silicon grains in the channel regions exhibited better current-voltage characteristics, as compared with the conventional top-gate ones. The proposed DG TFTs (W/L = 1/1 µm) had the field-effect mobility exceeding 550 cm 2 /V · s, an ON/OFF current ratio that is higher than 10 8 , superior short-channel characteristics, and higher current drivability. In addition, the device-to-device uniformity could be improved since grain growth could be artificially controlled by the spatial plateau structure. Index Terms-Double gate (DG), excimer laser crystallization (ELC), lateral grain growth, thin-film transistor (TFT).

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Section: Introductionmentioning

confidence: 99%

High-Performance Short-Channel Double-Gate Low-Temperature Polysilicon Thin-Film Transistors Using Excimer Laser Crystallization

Tsai

Wei

Lee

et al. 2007

IEEE Electron Device Lett.

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“…Tai et al developed a crystallization method using an excimer laser for crystalline nucleation formation and a CW green laser for lateral crystallization from the nucleation sites. They reported good TFTs with an electron mobility of 460 cm 2 /V s [41].…”

Section: Formation Of Large Crystalline Grainsmentioning

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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“…The low mobility is due to potential barriers formed at random grain boundaries (GBs) which trap carriers. Lateral grain growth (6)(7)(8) can reduce the effect of GBs, however, the mobility is still limited due to inevitable incorporation of the random GBs. If the location of the silicon islands is controlled, the position of the channel region of FETs can also be aligned inside the island.…”

Section: Single-grain Si Tftsmentioning

confidence: 99%

Single Grain Si TFTs for RF and 3D ICs

Ishihara¹,

Baiano²,

Chen³

et al. 2009

ECS Trans.

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Single-grain Si TFTs have been fabricated using accurate 2D location control of large Si grain with the µ-Czochralski process. TFTs fabricated inside the crystalline islands of 6 µm show a mobility (600cm 2 /Vs) as high as that of the SOI counterpart, despite of the low-temperature (<350 o C) process. By applying a tensile stress into the grain, the mobility surpasses even the SOI counterparts. We have succeeded in controlling crystallographic orientation of the location-controlled Si grains as well, by combination of metal induced lateral crystallization and the microCzochralski process. Owing to the orientation control, uniformity in device properties approaches to the level of the SOI counterpart. Using the high performance single-grain (SG) Si TFTs, we have fabricated RF amplifier. The cut-off frequency of the RF device is 5.5 GHz with a channel length of 1.5 µm. We have even succeeded to stack two SG-TFT layers with which CMOS inverters were fabricated. This will open several new applications in TFTs of RF wireless communication, 3D-ICs with device level integration, and flexible electronics.

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Performance of Poly-Si TFTs Fabricated by SELAX

Cited by 58 publications

References 11 publications

High-Performance Short-Channel Double-Gate Low-Temperature Polysilicon Thin-Film Transistors Using Excimer Laser Crystallization

High-Performance Short-Channel Double-Gate Low-Temperature Polysilicon Thin-Film Transistors Using Excimer Laser Crystallization

Laser crystallization for large-area electronics

Single Grain Si TFTs for RF and 3D ICs

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