Real Time Spectroscopic Ellipsometry Studies of the Solid Phase Crystallization of Amorphous Silicon

1998 ◽  
Vol 507 ◽  
Author(s):  
H. Fujiwara ◽  
Joohyun Koh ◽  
Yeeheng Lee ◽  
C. R. Wronski ◽  
R. W. Collins
Keyword(s):  
Amorphous Silicon ◽  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Volume Fraction ◽  
Solid Phase ◽  
Thin Layers ◽  
Crystallization Time ◽  
Calibration Data ◽  
Solid Phase Crystallization ◽  
Near Surface

ABSTRACTWe have introduced real time spectroscopic ellipsometry (RTSE) for characterization of the solid phase crystallization (SPC) of intrinsic and n-type amorphous silicon (a-Si:H) thin films. RTSE has several advantages in the study and design of SPC processes for thin film transistor and solar cell fabrication. These include the capability of obtaining (i) calibration data that yield the near surface temperature of the film during processing, (ii) the volume fraction of the crystalline Si component of the film continuously versus time during SPC, and (iii) a measurement of the grain size and quality of the final polycrystalline Si film. For the thin layers studied here (∼150-1000 Å), we demonstrate excellent fitting of the SPC dynamics to the Avrami-Johnson-Mehl theory for random nucleation and two-dimensional crystallite growth. For a-Si:H n-layers, the crystallization time over the range from 565 to 645°C appears to be weakly activated with an energy of 0.6 eV.

Stress Induced During the Solid-phase Crystallization of Amorphous Silicon Deposited by LPCVD

1995 ◽  
Vol 403 ◽  
Author(s):  
T. Mohammed-Brahim ◽  
K. Kis-Sion ◽  
D. Briand ◽  
M. Sarret ◽  
F. Lebihan ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Solid Phase ◽  
Chemical Vapor ◽  
In Situ Monitoring ◽  
Crystallization Time ◽  
Solid Phase Crystallization ◽  
Pressure Chemical ◽  
Hall Effect Measurements ◽  
Deposition Techniques

AbstractThe Solid Phase Crystallization (SPC) of amorphous silicon films deposited by Low Pressure Chemical Vapor phase Deposition (LPCVD) using pure silane at 550'C was studied by in-situ monitoring the film conductance. The saturation of the conductance at the end of the crystallization process is found transient. The conductance decreases slowly after the onset of the saturation. This degradation is also observed from other analyses such as ellipsometry spectra, optical transmission and Arrhenius plots of the conductivity between 250 and 570K. Hall effect measurements show that the degradation is due to a decrease of the free carrier concentration n and not to a decrease of the mobility. This indicates a constant barrier height at the grain boundaries. The decrease of n is then due to a defect creation in the grain. Hence, whatever the substrate used, an optimum crystallization time exists. It depends on the amorphous quality film which is determined by the deposition techniques and conditions and on the crystallization parameters.

Real-time optical spectroscopy study of solid-phase crystallization in hydrogenated amorphous silicon

2006 ◽  
Vol 89 (12) ◽  
pp. 121921 ◽  
Author(s):  
P. Stradins ◽  
D. L. Young ◽  
Y. Yan ◽  
E. Iwaniczko ◽  
Y. Xu ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Real Time ◽  
Optical Spectroscopy ◽  
Solid Phase ◽  
Hydrogenated Amorphous Silicon ◽  
Spectroscopy Study ◽  
Solid Phase Crystallization ◽  
Hydrogenated Amorphous

Optimization of the metal/silicon ratio on nickel assisted crystallization of amorphous silicon

2005 ◽  
Vol 869 ◽  
Author(s):  
L. Pereira ◽  
M. Beckers ◽  
R.M.S. Martins ◽  
E. Fortunato ◽  
R. Martins
Keyword(s):  
Amorphous Silicon ◽  
Spectroscopic Ellipsometry ◽  
Crystallization Time ◽  
Crystalline Fraction ◽  
Nickel Metal ◽  
Metal Induced Crystallization ◽  
Structural Improvement ◽  
Short Annealing ◽  
The One ◽  
Induced Crystallization

AbstractThe aim of this work is to optimize the metal/silicon ratio on nickel metal induced crystallization of silicon. For this purpose amorphous silicon layers with 80, 125 and 220 nm thick were used on the top of which 0.5 nm of Ni was deposited and annealed during the required time to full crystallize the a-Si. The data show that the 80 nm a-Si layer reaches a crystalline fraction of 95.7% (as detected by spectroscopic ellipsometry) after annealed for only 2 hours. No significant structural improvement is detected by ellipsometry neither by XRD when annealing the films for longer times. However, on 125 nm thick samples, after annealing for 2 hours the crystalline fraction is only 59.7%, reaching a similar value to the one with 80 nm only after 5 hours, with a crystalline fraction of 92.2%. Here again no significant improvements were achieved by using longer annealing times. Finally, the 220 nm thick a-Si sample is completely crystallized only after 10 hours annealing. These data clear suggest that the crystallization of thicker a-Si layers requires thicker Ni films to be effective for short annealing times. A direct dependence of the crystallization time on the metal/silicon ratio was observed and estimated.

Evolution of Crystallinity in Mixed-Phase (a+μc)-Si:H as Determined by Real Time Spectroscopic Ellipsometry

2003 ◽  
Vol 762 ◽  
Author(s):  
A. S. Ferlauto ◽  
G. M. Ferreira ◽  
R.J. Koval ◽  
J.M. Pearce ◽  
C.R. Wronski ◽  
...  
Keyword(s):  
Real Time ◽  
Spectroscopic Ellipsometry ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Cone Angle ◽  
Chemical Vapor ◽  
Mixed Phase ◽  
Thin Film Solar Cells ◽  
Nucleation Density ◽  
Microcrystalline Silicon

AbstractThe ability to characterize the phase of the intrinsic (i) layers incorporated into amorphous silicon [a-Si:H] and microcrystalline silicon [μc-Si:H] thin film solar cells is critically important for cell optimization. In our research, a new method has been developed to extract the thickness evolution of the μc-Si:H volume fraction in mixed phase amorphous + microcrystalline silicon [(a+μc)-Si:H] i-layers. This method is based on real time spectroscopic ellipsometry measurements performed during plasma-enhanced chemical vapor deposition of the films. In the analysis, the thickness at which crystallites first nucleate from the a-Si:H phase can be estimated, as well as the nucleation density and microcrystallite cone angle. The results correlate well with structural and solar cell measurements.

Comparison Between Rapid Thermal and Furnace Annealing for A-Si Solid Phase Crystallization

1996 ◽  
Vol 424 ◽  
Author(s):  
Reece Kingi ◽  
Yaozu Wang ◽  
Stephen J. Fonash ◽  
Osama Awadelkarim ◽  
John Mehlhaff
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Growth Time ◽  
Crystallization Time ◽  
Solid Phase Crystallization ◽  
Furnace Annealing ◽  
Lower Growth ◽  
Transient Time

AbstractRapid thermal annealing and furnace annealing for the solid phase crystallization of amorphous silicon thin films deposited using PECVD from argon diluted silane have been compared. Results reveal that the crystallization time, the growth time, and the transient time are temperature activated, and that the resulting polycrystalline silicon grain size is inversely proportional to the annealing temperature, for both furnace annealing and rapid thermal annealing. In addition, rapid thermal annealing was found to result in a lower transient time, a lower growth time, a lower crystallization time, and smaller grain sizes than furnace annealing, for a given annealing temperature. Interestingly, the transient time, growth time, and crystallization time activation energies are much lower for rapid thermal annealing, compared to furnace annealing.We propose two models to explain the observed differences between rapid thermal annealing and furnace annealing.

Polycrystalline Silicon Films Formed by Solid-Phase Crystallization of Amorphous Silicon: the Substrate Effects on Crystallization Kinetics and Mechanism

1996 ◽  
Vol 424 ◽  
Author(s):  
Y.-H. Song ◽  
S.-Y. Kang ◽  
K. I. Cho ◽  
H. J. Yoo ◽  
J. H. Kim ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Solid Phase Crystallization ◽  
Substrate Effects ◽  
Random Nucleation ◽  
Pressure Chemical ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
Induced Crystallization

AbstractThe substrate effects on the solid-phase crystallization of amorphous silicon (a-Si) have been extensively investigated. The a-Si films were prepared on two kinds of substrates, a thermally oxidized Si wafer (SiO2/Si) and a quartz, by low-pressure chemical vapor deposition (LPCVD) using Si2H6 gas at 470 °C and annealed at 600 °C in an N2 ambient for crystallization. The analysis using XRD and Raman scattering shows that crystalline nuclei are faster formed on the SiO2/Si than on the quartz, and the time needed for the complete crystallization of a-Si films on the SiO2/Si is greatly reduced to 8 h from ˜15 h on the quartz. In this study, it was first observed that crystallization in the a-Si deposited on the SiO2/Si starts from the interface between the a-Si film and the thermal oxide of the substrate, called interface-induced crystallization, while random nucleation process dominates on the quartz. The very smooth surface of the SiO2/Si substrate is responsible for the observed interface-induced crystallization of a-Si films.

On the transient amorphous silicon structures during solid phase crystallization

2013 ◽  
Vol 363 ◽  
pp. 172-177 ◽  
Author(s):  
F. Law ◽  
H. Hidayat ◽  
A. Kumar ◽  
P. Widenborg ◽  
J. Luther ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Solid Phase ◽  
Solid Phase Crystallization ◽  
Silicon Structures
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