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.

Experimental Analysis for Low-Temperature Poly-Si Films Produced by Using the Excimer Laser Annealing Method

2006 ◽  
Vol 505-507 ◽  
pp. 277-282 ◽  
Author(s):  
Yu Ru Chen ◽  
Long Sun Chao
Keyword(s):  
Grain Size ◽  
Excimer Laser ◽  
Glass Substrate ◽  
Laser Annealing ◽  
Pulse Number ◽  
Sio2 Layer ◽  
Excimer Laser Annealing ◽  
Melt Pool ◽  
Si Films ◽  
Annealing Method

This paper is to investigate the effects on grain size of different working conditions for making poly Si films by using the excimer laser annealing method. In this research, a KrF excimer laser of 248 nm in wavelength is used to irradiate a-Si films of 0.1 μm in thickness on glass substrate to produce poly-Si ones. The control parameters are laser intensity (200~500 mJ/cm2), pulse number (1~10 shots) and coverage fraction (0~100%). Besides, the effect of a SiO2 layer is also studied, which is utilized as a heat-isolated zone located between the Si film and glass substrate. Average grain sizes from SEM photos are used to analyze the effects of these parameters. Purely from the heat transfer view, the Si film obtains more energy would have the slower cooling or solidification rate, which results in the larger grain. From the experimental results, if the melt pool is within the range of Si film or does not contact its neighboring layer (SiO2 layer or glass substrate), the more absorbed energy from the higher energy intensity, the larger pulse number or the bigger coverage fraction can have the larger average grain size. However, with large enough energy, the melt pool could go through the Si film and touch the lower layer. This would induce much more nuclei due to the homogeneous nucleation in the pool and the heterogeneous nucleation near the interface between the film and the neighboring layer. The resulting grain size is much smaller than that of the former one. The transition points of these two cases for different control parameters can be obtained from the experimental results in this study. When the energy from the laser is small, the SiO2 layer acts like a heat absorber and makes the grain size smaller than that of not having the SiO2 layer. On the other hand, when the energy is large, the SiO2 layer becomes a heat insulator and makes the grain size larger.

Excimer Laser Annealing of Amorphous Silicon Films

1994 ◽  
Vol 336 ◽  
Author(s):  
J. Viatella ◽  
R.K. Singh ◽  
R.P.S. Thakur
Keyword(s):  
Grain Size ◽  
Amorphous Silicon ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Silicon Layer ◽  
Solidification Velocity ◽  
Excimer Laser Annealing ◽  
Active Matrix ◽  
Average Temperature ◽  
Low Temperature Processing

ABSTRACTLow temperature processing is necessary for the fabrication of thin-film transistors for electronics-on-glass applications, including active matrix flat-panel displays. One method to achieve this involves the use of pulsed excimer-laser annealing of an Amorphous silicon layer on top of an SiO2 layer. The intense UV laser is absorbed in the Amorphous silicon region, Maintaining a low average temperature. The thickness of the underlying SiO2 layer affects the solidification velocity and hence the grain size of the annealed layer. Previous work has concluded that the resultant grain size is small (<100 nm) and further work is needed in finding ways of increasing grain size. This paper describes how grain size is affected by varying the thickness of the SiO2 layer. Correlations will be discussed.between the solidification velocities and grain size as affected by the varying thickness of the SiO2 layer. The paper includes a comparison between experimental and theoretical results, using equations based on energy balance considerations.

Macro-Micro Modeling Analysis of Melting and Re-Solidification of Thin Si Films by Excimer Laser Annealing

2008 ◽  
Vol 594 ◽  
pp. 306-311
Author(s):  
Long Sun Chao ◽  
Chien Hung Chang
Keyword(s):  
Grain Size ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Transfer Problem ◽  
Phase Changes ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Micro Model ◽  
Excimer Laser Annealing ◽  
Si Films

In this work, an macro-micro model has been developed for the melting and resolidification of thin Si films induced by excimer-laser annealing. The macro-micro model, considering the formation of microstructures: nucleation and growth, can obtain the better results than macro-models. Except temperature distributions, the macro-micro models can offer more information about solidification process, such as undercooling, grain size, grain density etc. These data could help to predict the physical properties of materials. In this study, the finite difference method is utilized to solve the heat transfer problem. The specific heat/enthalpy method and the source term scheme are employed to handle the absorbed and released latent heat. The algorithm that allows for nucleation is based on classical nucleation theory. Accordingly, the model enables the prediction of grain size, as well as the calculation of other critical responses of the a-Si film, such as undercooling. From the computational results, it can be found that when the laser fluence is higher, the cooling rate after laser irradiation is lower, the maximum undercooling is smaller and the grain size is larger or the grain density is lower. The average grain sizes, obtained from the simulation results of the proposed model, agree fairly well with those from the experimental data reported in the literature. It can also be found that the reflectivity of the surface gives a good way to observe the phase changes and the melting duration.

Polycrystalline Silicon Films on SiO2 Substrate Treated by Excimer Laser Annealing

2013 ◽  
Vol 750-752 ◽  
pp. 946-951
Author(s):  
Chun Yan Duan ◽  
Bin Ai ◽  
Rong Xue Li ◽  
Chao Liu ◽  
Jian Jun Lai ◽  
...  
Keyword(s):  
Grain Size ◽  
Excimer Laser ◽  
Polycrystalline Silicon ◽  
Laser Annealing ◽  
Laser Energy ◽  
Chemical Vapor ◽  
Excimer Laser Annealing ◽  
Before And After ◽  
Si Films ◽  
Polycrystalline Silicon Films

Selected area laser-annealed polycrystalline silicon (p-Si) thin films were prepared by a 248 nm excimer laser. 1 μm thick p-Si films with grain size less than 100 nm were deposited on SiO2substrate by chemical vapor deposition using atmospheric pressure (APCVD). Grain sizes before and after annealing was examined by scanning electron microscopy (SEM) and the mechanism of grain growth was discussed in detail. The maximum grain size of a selected area laser-annealed p-Si film can be increased from 100 nm up to 2.9 μm on SiO2substrate by using appropriate laser energy densities. It indicated that silicon grains in laser-annealed regions had grown up competitively with three stages.

Heat Transfer and Phase Transformations in Laser Annealing of Thin a-Si Films

2001 ◽  
Author(s):  
Seung-Jae Moon ◽  
Minghong Lee ◽  
Costas P. Grigoropoulos
Keyword(s):  
Laser Annealing ◽  
Thermal Emission ◽  
Electrical Conductance ◽  
Nanosecond Laser ◽  
Solidification Velocity ◽  
Emission Measurement ◽  
Excimer Laser Annealing ◽  
In Situ Experiments ◽  
Si Films

Abstract The liquid-solid interface motion and the temperature history of thin Si films during excimer laser annealing are observed by in situ experiments combining time-resolved (∼lns) thermal emission measurements, optical reflectance and transmittance at near-IR wavelengths and electrical conductance measurements. The spontaneous nucleation temperature in the supercooled liquid melt is studied from the thermal emission measurement A new double laser recrystallization technique using a temporally modulated CW Ar+ laser in conjunction with a superposed nanosecond laser pulse produces lateral grain growth at the irradiated spot. The laser melting process is numerically simulated. High-resolution laser flash photography enabled in-situ direct visualization of the resolidification process. The images reveal lateral solidification velocity of about 10 m/s.

Enlargement of Grain Size and Location Control of Grain in Excimer-laser Crystallization of Si Film

2006 ◽  
Vol 910 ◽  
Author(s):  
Wenchang Yeh ◽  
Dunyuan Ke ◽  
Chunjun Zhuang
Keyword(s):  
Grain Size ◽  
Light Beam ◽  
Excimer Laser ◽  
Conventional Method ◽  
Growth Process ◽  
Laser Annealing ◽  
Glass Structure ◽  
Control Technique ◽  
Back Side ◽  
Excimer Laser Annealing

AbstractA technique for enlargement of grain size were shown and a technique for location controlled super lateral growth (SLG) grain in excimer laser annealing (ELA) were proposed and realized. In the technique for grain size enlargement, the grain size was enlarged to 10£gm that is more than 10 times larger than that in conventional method(~0.8£gm). The proposed sample structure was Si film/light absorptive film/Glass structure with applying the laser light from the back side of glass substrate. Time resolved(~1ns) optical measurement (TROM) revealed that the melt duration of Si film was increased to 800ns that is also 10 times longer than that in conventional method. As for the grain location control technique, a new method contains pre seeding process and post growth process were proposed and realized. In the pre seeding process, micro light beam(£g-light beam) was exposed to Si film to form a grain within the crystallized spot. £g-light beam was formed by micro-lens-array(MLA). After post growth process, single grain array with the diameters of 6£gm was formed in a period of 10£gm.

Low-Temperature Polycrystalline Silicon Thin-Film Transistors and Circuits on Flexible Substrates

MRS Bulletin ◽  
2006 ◽  
Vol 31 (6) ◽  
pp. 461-465 ◽  
Author(s):  
P.C. van der Wilt ◽  
M.G. Kane ◽  
A.B. Limanov ◽  
A.H. Firester ◽  
L. Goodman ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Laser Annealing ◽  
Defect Density ◽  
Solid Phase ◽  
Flexible Substrates ◽  
Full Potential ◽  
Laser Crystallization ◽  
Silicon Thin Film ◽  
Excimer Laser Annealing ◽  
Si Films

AbstractLow-defect-density polycrystalline Si on flexible substrates can be instrumental in realizing the full potential of macroelectronics. Direct deposition or solid-phase crystallization techniques are often incompatible with polymers and produce materials with high defect densities. Excimer-laser annealing is capable of producing films of reasonable quality directly on polymer and metallic substrates. Sequential lateral solidification (SLS) is an advanced pulsed-laser-crystallization technique capable of producing Si films on polymers with lower defect density than can be obtained via excimer-laser annealing. Circuits built directly on polymers using these SLS films show the highest performance reported to date.

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