Enhancement of On/Off Current Ratio of Poly-Silicon TFT by Selective Laser-Induced Crystallization of Active Layer

1997 ◽  
Vol 471 ◽  
Author(s):  
Jae-Hong Jeon ◽  
Cheol-Min Park ◽  
Hong-Seok Choi ◽  
Cheon-Hong Kim ◽  
Min-Koo Han
Keyword(s):  
Leakage Current ◽  
Excimer Laser ◽  
Active Layer ◽  
Laser Annealing ◽  
Wave Length ◽  
Excimer Laser Annealing ◽  
Current Ratio ◽  
Ito Film ◽  
Conduction Channel ◽  
Induced Crystallization

ABSTRACTWe have proposed the new poly-Si TFT which reduces the leakage current effectively by employing highly resistive a-Si region in the channel. The active layer of proposed device is crystallized selectively by employing excimer laser annealing while the both sides of channel near the source/drain are not recrystallized and remained as a-Si. Unlikely LDD or offset structure, the a-Si region which is designed to reduce the leakage current acts as the conduction channel of carriers under the ON state, so that the ON current is decreased very little. The selectively crystallized active layer can be fabricated by irradiating the excimer laser through ITO film of which transmittance at the wave length of laser is selectively adjusted. In the course of fabricating the proposed device, any additional photo masking step is not necessary and misalign problem is eliminated. The experimental results show that the ON/OFF current ratio of proposed poly-Si TFT is 106 while that of conventional one is 105.

High-Performance Poly-Si TFTs with Multiple Selectively Doped Regions in the Active Layer

2000 ◽  
Vol 621 ◽  
Author(s):  
Min-Cheol Lee ◽  
Juhn-Suk Yoo ◽  
Kee-Chan Park ◽  
Sang-Hoon Jung ◽  
Min-Koo Han ◽  
...  
Keyword(s):  
Leakage Current ◽  
Excimer Laser ◽  
High Performance ◽  
Laser Annealing ◽  
Channel Length ◽  
Depletion Region ◽  
Excimer Laser Annealing ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Excimer Laser Irradiation

ABSTRACTWe have proposed and fabricated a new poly-Si TFT that employs selectively doped regions between the source and drain in order to reduce leakage current without the sacrifice of the on current. In the proposed poly-Si TFTs, the selectively doped regions where doping concentration is identical to that of source/drain, reduce the effective channel length during the on state. Under the off state, the selectively doped regions may reduce the lateral electric field induced in the depletion region near drain so that the leakage current reduces considerably. The experimental data of the proposed TFT shows that it has the high on-current, low leakage current and low threshold voltage when compared with conventional TFT. The fabrication steps for the proposed TFT are reduced because ion-implantation for source/drain and selectively doped regions is performed simultaneously prior to an excimer laser irradiation. It should be noted that, in the proposed TFT, only one excimer laser annealing is required while two excimer laser annealing steps are required in conventional TFT.

The Influence of Low Temperature Pre-Annealing on the Defect Removal and the Reduction of Junction Depth in Excimer Laser Annealing

2002 ◽  
Vol 717 ◽  
Author(s):  
Sungkweon Baek ◽  
Taesung Jang ◽  
Hyunsang Hwang
Keyword(s):  
Low Temperature ◽  
Leakage Current ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Defect Density ◽  
Process Conditions ◽  
Junction Depth ◽  
Excimer Laser Annealing ◽  
Transmission Electron Microscopy Analysis ◽  
Shallow Junction

AbstractThe influence of low temperature pre-annealing on p+/n ultra-shallow junction was investigated. An ultra-shallow junction was formed by means of B2H6 plasma doping at an energy of 500V. The activation was performed by excimer laser annealing. To study the low temperature annealing prior to laser annealing, furnace annealing at 300°C∼500°C for 5min was performed. Compared with control samples with no pre-annealing, the low temperature preannealing significantly improves junction characteristics, resulting in a reduction of junction depth and a lower leakage current density. A cross-sectional transmission electron microscopy analysis confirmed the lower defect density, which explains the lower leakage current. By optimizing the process conditions, excellent electrical characteristics of the p+/n ultra-shallow junction such as a junction depth of 28nm and a sheet resistance of 250Δ/sq. can be obtained.

Excimer Laser Recrystallization of Selectively Floating a-Si Active Layer for Large-Grained Poly-Si Film

2001 ◽  
Vol 664 ◽  
Author(s):  
Cheon-Hong Kim ◽  
Juhn-Suk Yoo ◽  
In-Hyuk Song ◽  
Min-Koo Han
Keyword(s):  
Excimer Laser ◽  
Active Layer ◽  
Laser Annealing ◽  
Layer Structure ◽  
Excimer Laser Annealing ◽  
Lateral Direction ◽  
Thermal Insulating ◽  
Laser Recrystallization ◽  
Lateral Temperature ◽  
Annealing Method

ABSTRACTWe report a new excimer laser annealing method by employing selectively floating a-Si active layer structure in order to increase the grain size of poly-Si film. The floating a-Si region blocks the heat conduction into the underlying substrate due to high thermal-insulating property of an air so that the lateral temperature gradient is successfully induced by the proposed simple air-gap structure. Our experimental results show that large grains were grown in the lateral direction from the edge to the center of the floating active region. The large grains exceeding 4 m were successfully obtained with only one laser irradiation.

Excimer Laser Annealed Poly-Si TFT Technologies

1995 ◽  
Vol 377 ◽  
Author(s):  
Fujio Okumura ◽  
Kenji Sera ◽  
Hiroshi Tanabe ◽  
Katsuhisa Yuda ◽  
Hiroshi Okumura
Keyword(s):  
Energy Density ◽  
Leakage Current ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Laser Energy ◽  
Gate Insulator ◽  
Excimer Laser Annealing ◽  
Threshold Voltage Shift ◽  
Si Films ◽  
Current Reduction

ABSTRACTThis paper describes the excimer laser annealed (ELA) poly-Si TFT technologies in terms of excimer laser annealing of Si films, the leakage current, and the TFT stability. A laser energy density and a shot dependencies of TFT characteristics was analyzed by TEM, SEM, and Raman. The mobility increases with increasing not only the energy density but also the shot density. The mobility increase with the energy density is due to the grain size enlargement. On the other hand, the mobility increase up to 10 to 20 shots is due to a decrease of defects, including small grains, grain boundaries and defects inside grains. The contribution of grain-growth is small. The ELA TFT has a micro-offset structure to reduce the leakage current. Moreover, we have proposed a dynamic leakage current reduction structure. The combination of these technologies provides a sufficiently small leakage current for AMLCDs. The stability of the gate insulator was analyzed. The TFT shows negative threshold voltage shift under gate bias stress. This is due to water penetration and the subsequent field activated chemical reaction in the gate insulator. The dissociation of Si-OH bonds with hydrogen-bonded water was a fundamental contributor. The shift was suppressed sufficiently by hydrogen passivation. Obtained ELA TFTs;s have mobilities of over 100 cm2/Vsec, threshold voltages of less than 3 V, effective leakage currents of less than 10−13 A, and are stable more than 10 years.

Effects of Excimer Laser Annealing on InGaZnO4Thin-Film Transistors Having Different Active-Layer Thicknesses Compared with Those on Polycrystalline Silicon

2009 ◽  
Vol 48 (11) ◽  
pp. 115505 ◽  
Author(s):  
Mitsuru Nakata ◽  
Kazushige Takechi ◽  
Shinya Yamaguchi ◽  
Eisuke Tokumitsu ◽  
Hirotaka Yamaguchi ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Active Layer ◽  
Polycrystalline Silicon ◽  
Laser Annealing ◽  
Excimer Laser Annealing

Intensity-Modulated Excimer Laser Annealing to Obtain (001) Surface-Oriented Poly-Si Films on Glass: Molecular Dynamics Study

2008 ◽  
Author(s):  
Norie Matsubara ◽  
Tomohiko Ogata ◽  
Takanori Mitani ◽  
Shinji Munetoh ◽  
Teruaki Motooka
Keyword(s):  
Molecular Dynamics ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Excimer Laser Annealing ◽  
Intensity Modulated ◽  
Si Films

Large-Grain Doped Poly-Si Films Fabricated Using New Excimer Laser Annealing Technique

1992 ◽  
Vol 283 ◽  
Author(s):  
Hiroshi Iwata ◽  
Tomoyuki Nohda ◽  
Satoshi Ishida ◽  
Takashi Kuwahara ◽  
Keiichi Sano ◽  
...  
Keyword(s):  
Grain Size ◽  
Sheet Resistance ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Solidification Velocity ◽  
Excimer Laser Annealing ◽  
Arf Excimer Laser ◽  
Si Films

ABSTRACTThe grain size of phosphorous (P)-doped poly-Si film has been enlarged to about 5000 Å by controlling the solidification velocity of molten Si during ArF excimer laser annealing. The drastically enlarged grain has few defects inside the grain. It has been confirmed that control of the solidification velocity is effective for P-doped poly-Si similar to the case of non-doped poly-Si films. In addition, a sheet resistance of 80 Ω/□ (ρ = 4 × 10-4 Ω · cm) has been achieved for very thin (500 Å) films by recrystallizing PECVD P-doped a-Si films.

Grain Enlargement of Polycrystalline Silicon by Multipulse Excimer Laser Annealing: Role of Hydrogen

2006 ◽  
Vol 45 (4A) ◽  
pp. 2726-2730 ◽  
Author(s):  
Naoya Kawamoto ◽  
Atsushi Masuda ◽  
Naoto Matsuo ◽  
Yasuhiro Seri ◽  
Toshimasa Nishimori ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Polycrystalline Silicon ◽  
Laser Annealing ◽  
Excimer Laser Annealing
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