Super-lateral-growth regime analysis in long-pulse-duration excimer-laser crystallization of a-Si films on SiO 2

1999 ◽  
Vol 68 (6) ◽  
pp. 631-635 ◽  
Author(s):  
E. Fogarassy ◽  
S. de Unamuno ◽  
B. Prevot ◽  
P. Boher ◽  
M. Stehle ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Excimer Laser ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
Growth Regime ◽  
Excimer Laser Crystallization ◽  
Si Films ◽  
Long Pulse ◽  
Regime Analysis

Observation of super lateral growth in long pulse (170 ns) excimer laser crystallization of a-Si films

2003 ◽  
Vol 427 (1-2) ◽  
pp. 319-323 ◽  
Author(s):  
A. Pecora ◽  
R. Carluccio ◽  
L. Mariucci ◽  
G. Fortunato ◽  
D. Murra ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
Excimer Laser Crystallization ◽  
Si Films ◽  
Long Pulse

Excimer-Laser Crystallization of Si Films Via Bi-Directional Irradiation of Dual-Layer Films on Transparent Substrates

1995 ◽  
Vol 397 ◽  
Author(s):  
Jung H. Yoon ◽  
James S. Im
Keyword(s):  
Excimer Laser ◽  
Thermal Environment ◽  
Thermal Evolution ◽  
Bottom Layer ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
Projection System ◽  
Substrate Heating ◽  
Excimer Laser Crystallization ◽  
Si Films

ABSTRACTIn this paper, we report on a new excimer-laser crystallization (ELC) method that is highly effective in extending the super-lateral growth (SLG) distance and which does not involve any preheating of the substrate. The technique utilizes bi-directional irradiation of a dual layer Si film stack (separated by an oxide layer) deposited on a quartz wafer. The top layer is irradiated with a projection system which transfers a mask image in order to produce grain-boundary-location-controlled (GLC) regions, and the bottom layer, upon irradiation with a uniform beam, acts as a medium that favorably affects the thermal evolution of the top layer. The technique is effective and attractive in that the heating is spatially and temporally localized in an optimal manner. The thermal environment required for extending the SLG distance, as is induced by the melting and solidification of the bottom layer, is physically regulated by the melting temperature of Si, and the enthalpy difference between liquid and solid can be used to initially store and subsequently release heat. Using the method, we were able to attain GLC regions with widths up to 10 μm in 1000-Å Si films without any substrate heating. We elaborate on the applicability of the method to various artificially controlled super-lateral growth (ACSLG) techniques, and discuss process optimization by means of varying the multilayer configuration.

A Novel Two-Pass Excimer Laser Crystallization Process to Obtain Homogeneous Large Grain Polysilicon

1999 ◽  
Vol 558 ◽  
Author(s):  
L. Mariucci ◽  
R. Carluccio ◽  
A. Pecora ◽  
V. Foglietti ◽  
G. Fortunato ◽  
...  
Keyword(s):  
Excimer Laser ◽  
Crystallization Process ◽  
Laser Energy ◽  
Spatial Modulation ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
First Pass ◽  
Wide Energy ◽  
Excimer Laser Crystallization ◽  
Polysilicon Tft

ABSTRACTNew approach to control the lateral growth mechanism through the opportune spatial modulation of the absorbed laser energy and with a two-pass excimer laser crystallization process is presented. In the first pass, spatial modulation of the light intensity has been obtained by irradiating the sample through a patterned mask in contact with the sample. Lateral growth is triggered when the irradiated regions are fully melted and a lateral extension of the grains in excess to 1 μm has been observed for samples irradiated at RT. In order to homogeneously crystallize the sample, the film can be re-irradiated (second pass) without the mask. By using opportune energy densities it can be induced a complete melting of the residual a-Si regions (masked areas during the first pass), while partially melting the polysilicon regions (unmasked areas during the first pass). Different mask geometries have been investigated and for optimized conditions, the sample area can be fully covered with laterally grown grains. The proposed novel technique can be rather attractive for polysilicon TFT fabrication, being characterized by only a two laser-shot process and wide energy density windows.

Excimer-Laser Crystallization of Patterned Si Films At High Temperatures Via Artificially Controlled Super-Lateral Growth

1995 ◽  
Vol 397 ◽  
Author(s):  
H. Jin Song ◽  
James S. Im
Keyword(s):  
Substrate Temperature ◽  
Single Crystal ◽  
Excimer Laser ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
High Substrate ◽  
Temperature Method ◽  
Main Portion ◽  
Si Films ◽  
Rate Ratios

ABSTRACTBased on the artificially controlled super-lateral growth approach, we have developed a novel excimer-laser-based high-substrate-temperature method for producing single-crystal Si islands on SiO2. By irradiating a photolithographically preconfigured sample, complete melting of an Si film is induced only at precisely predesignated locations within patterned and physically isolated islands. An intentionally incompletely melted section within each island initiates lateral growth of crystalline grains. A “bottleneck” portion of the island permits only one of the laterally growing grains to propagate into the main portion of the island. The low nucleation-to-growth-rate ratios that are attainable with high substrate temperatures (1000–1200 °C) can lead to nearly unlimited lateral growth distances; with a proper combination of the substrate temperature and the island dimension, the main area of an island—up to 50×50 μm2 in area—is readily converted into a large single-crystal region.

Excimer Laser Crystallization of Nanocrystalline Silicon Thin Films

2015 ◽  
Vol 1120-1121 ◽  
pp. 361-368
Author(s):  
Li Jie Deng ◽  
Wei He ◽  
Zheng Ping Li
Keyword(s):  
Thin Films ◽  
Energy Density ◽  
Excimer Laser ◽  
Silicon Film ◽  
Threshold Energy ◽  
Nanocrystalline Silicon ◽  
Lateral Growth ◽  
Laser Crystallization ◽  
Silicon Thin Films ◽  
Excimer Laser Crystallization

Nanocrystalline silicon (nc-Si) thin film on glass substrate is subjected to excimer laser crystallized by varying the laser energy density in the range of 50~600 mJ/cm2. The effect of excimer laser crystallization on the structure of silicon film is investigated using Raman spectroscopy, X-ray diffraction, atomic force microscopy and scanning electron microscopy. The results show that polycrystalline silicon thin films can be obtained by excimer laser crystallization of nc-Si films. A laser threshold energy density of 200 mJ/cm2 is estimated from the change of crystalline fraction and surface roughness of the treated films. The growth of grain is observed and the crystallization mechanism is discussed based on the super lateral growth model. The nanocrystalline silicon grains in the films act as seeds for lateral growth to large grains.

Long-Pulse Duration Excimer Laser Processing in the Fabrication of High Performance Polysilicon TFTs for Large Area Electronics

2001 ◽  
Vol 685 ◽  
Author(s):  
E. Fogarassy ◽  
B. Prévot ◽  
S. de Unamuno ◽  
C. Prat ◽  
D. Zahorski ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Excimer Laser ◽  
Laser Processing ◽  
High Performance ◽  
Microstructural Analysis ◽  
Neutral Atmosphere ◽  
Large Area ◽  
Electrical Stress ◽  
Si Films ◽  
Long Pulse

AbstractIn this work, was investigated both numerically and experimentally, the excimer laser processing of a-Si films deposited on SiO2-coated glass substrates, using the very large area (∼ 20 cm2) and long pulse duration (200 ns) excimer source from SOPRA Company. Experiments were carried out in air or in neutral atmosphere, using both the single- and multi-shot mode. From the microstructural analysis of the laser irradiated area the formation of a large-grained material through the so-called SLG regime was evidenced. In addition, the application of a multi-shot process was demonstrated to be very efficient to prepare uniform polysilicon layers with enlarged grain sizes (up to 1.5 µm after 20 shots). Finally, poly-Si TFTs prepared in the optimized conditions (multi-shot, neutral ambience) exibited field effect mobilities up to 235 cm2/V.s (for N-type) and 84 cm2/V.s (for P-type), with fairly uniform device characteristics over large area and excellent stability under electrical stress.

The Effect of Film Thickness and Pulse Duration Variation in Excimer Laser Crystallization of Thin Si Films

1996 ◽  
Vol 452 ◽  
Author(s):  
J. P. Leonard ◽  
M. A. Bessette ◽  
V. V. Gupta ◽  
James S. Im
Keyword(s):  
Energy Density ◽  
Film Thickness ◽  
Partial Melting ◽  
Pulse Duration ◽  
Excimer Laser ◽  
Silicon Film ◽  
Silicon Films ◽  
Laser Crystallization ◽  
Crystal Silicon ◽  
Excimer Laser Crystallization

AbstractRecognizing that the processing window in conventional excimer laser crystallization corresponds mainly to the partial melting regime, and that this can be properly simulated using a one-dimensional model, we investigate numerically the melting and solidification of thin silicon films on SiO2. Here a portion of the silicon film is melted and subsequent vertical solidification is initiated from the lower interface bounding the unmelted region. Upper and lower energy density limits for this regime are calculated for crystal silicon films of thickness 10 to 300 nm, and for pulse duration ranging from 10 to 200 ns. These calculations show that increasing pulse duration requires proportionally more incident energy density to partially melt the film, while decreasing film thickness reduces the range of energy densities over which partial melting can occur. The results are explained in terms of characteristic thermal diffusion distances and the enthalpy change associated with melting. In view of the results we discuss optimization of the conventional excimer laser crystallization and the avoidance of complete melting during the process.

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