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.

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.

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.

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.

Enlargement of Poly-Si Film Grain Size by Excimer Laser Annealing and Its Application to High-Performance Poly-Si Thin Film Transistor

1991 ◽  
Vol 30 (Part 1, No. 12B) ◽  
pp. 3700-3703 ◽  
Author(s):  
Hiroyuki Kuriyama ◽  
Seiichi Kiyama ◽  
Shigeru Noguchi ◽  
Takashi Kuwahara ◽  
Satoshi Ishida ◽  
...  
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Excimer Laser ◽  
High Performance ◽  
Laser Annealing ◽  
Thin Film Transistor ◽  
Excimer Laser Annealing ◽  
Si Thin Film

Lateral Grain Growth in the Excimer Laser Crystallization of Poly-Si

1994 ◽  
Vol 321 ◽  
Author(s):  
H. Kuriyama ◽  
K. Sano ◽  
S. Ishida ◽  
T. Nohda ◽  
Y. Aya ◽  
...  
Keyword(s):  
Grain Size ◽  
Excimer Laser ◽  
Laser Annealing ◽  
Field Effect Mobility ◽  
Laser Crystallization ◽  
Excimer Laser Annealing ◽  
Short Processing Time ◽  
Low Temperature Processing ◽  
Excimer Laser Crystallization ◽  
Annealing Method

ABSTRACTWe have succeeded in obtaining nondoped, thin poly-Si film (thickness ∼500Å) with excellent crystallinity and large grain size (Maximum grain size ∼4.5 μ m) by an excimer laser annealing Method, which offers the features of low-temperature processing and a short processing time. The grain size distribution shrinks in the region around 1.5 μ m and this poly-Si film exhibits a strong (111) crystallographic orientation. Poly-Si thin film transistors using these films show quite a high field effect mobility of 440cm2/V · s below 600°C process.

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