Silicide Formation with Tungsten Deposited from W-LPCVD; The Role of Back Surface Conditions

1992 ◽  
Vol 260 ◽  
Author(s):  
S. -L. Zhang ◽  
M. Östling ◽  
U. Smith ◽  
R. Buchta
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Front Surface ◽  
Back Surface ◽  
Surface Oxide Layer ◽  
Silicide Formation ◽  
Surface Conditions ◽  
Tungsten Hexafluoride ◽  
Pressure Chemical ◽  
Isothermal Heat Treatments

Tungsten (W) films were deposited on the front surface of float-zone (FZ) Si wafers, from tungsten hexafluoride (WF6) by low pressure chemical vapor deposition (LPCVD). The back surface conditions of the Si wafers was the major concern of this study. Various back surface coatings were investigated, tungsten, thermal SiO2 and LPCVD-Si3N4. Isothermal heat treatments were performed in an argon flow furnace at 760°C for 8 to 30 min. The silicide formation was monitored by Rutherford backscattering spectrometry (RBS). No difference in the silicidation rate was found on the wafers with a back surface oxide layer as compared to that of the reference wafers with no back surface coating. However, for wafers with the back surface covered with Si3N4 or W, a retarded silicidation rate was observed. This phenomenon appeared to be insensitive to the presence of a cap layer (PECVD-SiO2) on the W films before annealing. A model including the behavior of point defects is proposed to provide an explanation to this observation.

A study of silicide formation from LPCVD-tungsten films: Film texture and growth kineticsa

1991 ◽  
Vol 6 (9) ◽  
pp. 1886-1891 ◽  
Author(s):  
S-L. Zhang ◽  
R. Buchta ◽  
M. Östling
Keyword(s):  
Chemical Vapor ◽  
Silicide Formation ◽  
X Ray Diffraction ◽  
Inexpensive Method ◽  
X Ray ◽  
Si Substrates ◽  
Kinetics Studies ◽  
Tungsten Hexafluoride ◽  
Pressure Chemical ◽  
History Of

Tungsten disilicide (WSi2) was formed by annealing tungsten (W) films of 330 nm and 750 nm prepared by low pressure chemical vapor deposition (LPCVD) from tungsten hexafluoride (WF6) on Czochralski 〈100〉-Si substrates. The silicide was found to grow continuously from the WSi2/W interface. The thickness of the formed WSi2 was observed by Rutherford backscattering measurements (RBS) to increase parabolically with the annealing time, with an activation energy of 2.6 eV/atom. The crystal structure of the formed WSi2 and the unreacted W films was analyzed using x-ray diffraction (XRD) technique. The thermal history of the samples was found to play an important role for the film texture of the unreacted W and formed WSi2, indicating that the fast and inexpensive method, XRD, applied as a thickness monitor for kinetics studies of WSi2 growth will undoubtedly introduce large errors. The as-deposited W (on Si) and the unreacted W (on WSi2) were found to be under a tensile stress, as observed by means of the XRD technique.

scholarly journals Surface Passivation Studies on n+pp+ Bifacial Solar Cell

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Suhaila Sepeai ◽  
M. Y. Sulaiman ◽  
Kamaruzzaman Sopian ◽  
Saleem H. Zaidi
Keyword(s):  
Solar Cell ◽  
Screen Printing ◽  
Surface Passivation ◽  
Chemical Vapor ◽  
Front Surface ◽  
Back Surface ◽  
Antireflective Coatings ◽  
Solar Cell Performance ◽  
Sandwiched Structure ◽  
Bifacial Solar Cell

Bifacial solar cell is a specially designed solar cell for the production of electricity from both sides of the solar cell. It is an active field of research to make photovoltaics (PV) more competitive by increasing its efficiency and lowering its costs. We developed an n+pp+ structure for the bifacial solar cell. The fabrication used phosphorus-oxy-trichloride (POCl3) diffusion to form the emitter and Al diffusion using conventional screen printing to produce the back surface field (BSF). The n+pp+ bifacial solar cell was a sandwiched structure of antireflective coatings on both sides, Argentum (Ag) as a front contact and Argentum/Aluminum (Ag/Al) as a back contact. This paper reports the solar cell performance with different surface passivation or antireflecting coatings (ARC). Silicon nitride (SiN) deposited by Plasma-Enhanced Chemical Vapor Deposition (PECVD), thermally grown silicon dioxide (SiO2), PECVD-SiO2, and SiO2/SiN stack were used as ARC. The efficiency obtained for the best bifacial solar cell having SiN as the ARC is 8.32% for front surface illumination and 3.21% for back surface illumination.

Atmospheric pressure chemical vapor deposition of TiN from tetrakis(dimethylamido)titanium and ammonia

1996 ◽  
Vol 11 (4) ◽  
pp. 989-1001 ◽  
Author(s):  
Joshua N. Musher ◽  
Roy G. Gordon
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Scanning Electron Micrographs ◽  
X Ray ◽  
High Ammonia ◽  
Pressure Chemical

Near stoichiometric titanium nitride (TiN) was deposited from tetrakis(dimethylamido)titanium (TDMAT) and ammonia using atmospheric pressure chemical vapor deposition. Experiments were conducted in a belt furnace; static experiments provided kinetic data and continuous operation uniformly coated 150-mm substrates. Growth rate, stoichiometry, and resistivity are examined as functions of deposition temperature (190−420 °C), ammonia flow relative to TDMAT (0−30), and total gas-flow rate (residence time 0.3−0.6 s). Films were characterized by sheet resistance measurements, Rutherford Backscattering Spectrometry, and X-Ray Photoelectron Spectrometry. Films deposited without ammonia were substoichiometric (N/Ti, 0.6−0.75), contained high levels of carbon (C/Ti = 0.25−0.40) and oxygen (O/Ti = 0.6−0.9), and grew slowly. Small amounts of ammonia (NH3/TDMAT ≥ 1) brought impurity levels down to C/Ti, 0.1 and O/Ti = 0.3−0.5. Ammonia increased the growth rates by a factor of 4−12 at temperatures below 400 °C. Films 500 Å thick had resistivities as low as 1600 μΩ-cm when deposited at 280 °C and 1500 μΩ-cm when deposited at 370 °C. Scanning electron micrographs indicate a smooth surface and poor step coverage for films deposited with high ammonia concentrations.

Heteroepitaxial Si1-x-yGex Cy Layer Growth on (100)Si by Atmospheric Pressure Chemical Vapor Deposition

1995 ◽  
Vol 399 ◽  
Author(s):  
Z. Atzmon ◽  
A. E. Bair ◽  
T. L. Alford ◽  
D. Chandrasekhar ◽  
David J. Smith ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Layer Growth ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Good Crystallinity ◽  
Pressure Chemical

ABSTRACTThin heteroepitaxial films of Si1-x-yGexCy have been grown on (100)Si substrates using atmospheric pressure chemical vapor deposition at 550 and 700°C. The crystallinity, composition and microstructure of the SiGeC films were characterized using Rutherford backscattering spectrometry (ion channeling), secondary-ion-mass-spectrometry and cross-sectional transmission electron microscopy. SiGeC films with up to 2% C were grown at 700°C with good crystallinity and very few interracial defects, while misfit dislocations at the SiGe/Si interface were observed for SiGe films grown under the same conditions. This difference indicates that the presence of carbon in the SiGe matrix increases the critical thickness of the grown layers. SiGeC thin films (>110 nm) with up to 3.5% C were grown at 550°C with good crystallinity. The crystallinity of the films grown at lower temperature (550°C) was less sensitive to the flow rate of the C source (C2H4), which enabled growth of single crystal SiGeC films with higher C content.

Combinatorial Chemical Vapor Deposition of Metal Silicate Films Using Tri(t -butoxy) silanol and Anhydrous Metal Nitrates

2003 ◽  
Vol 804 ◽  
Author(s):  
Lijuan Zhong ◽  
Fang Chen ◽  
Stephen A. Campbell ◽  
Wayne L. Gladfelter
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Rutherford Backscattering Spectrometry ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Rutherford Backscattering ◽  
Chemical Vapor Deposition Reactor ◽  
Metal Nitrates ◽  
Metal Silicate ◽  
Pressure Chemical

ABSTRACTA modified low-pressure chemical vapor deposition reactor was used to create compositional spreads of MO2/SiO2 films (M = Hf, Zr and Sn) using tri(t-butoxy) silanol and anhydrous metal nitrates of hafnium, zirconium and tin at temperatures below 250 °C. The compositional spreads formed by this process were characterized by ellipsometry and Rutherford backscattering spectrometry. A survey of possible reactions involved in the deposition is included.

Development of High Efficiency Thin Film Polycrystalline Silicon Solar Cells using Vest Process

1997 ◽  
Vol 485 ◽  
Author(s):  
T. Ishihara ◽  
S. Arimoto ◽  
H. Morikawa ◽  
Y. Nishimoto ◽  
Y. Kawama ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
High Efficiency ◽  
Chemical Vapor ◽  
Front Surface ◽  
Zone Melting ◽  
Back Surface ◽  
Large Area ◽  
Hydrogen Implantation ◽  
Si Films

AbstractThin film Si solar cell has been developed using Via-hole Etching for the Separation of Thin films(VEST) process. The process is based on SOI technology of zone-melting recrystallization (ZMR) followed by chemical vapor deposition (CVD), separation of thin film, and screen printing. Key points for achieving high efficiency are (1)quality of Si films, (2)back surface emitter (BSE), (3)front surface emitter etch-back process, (4)back surface field (BSF) layer thickness and its resistivity, and (5)defect passivation by hydrogen implantation. As a result of experiments, we have achieved 16% efficiency(Voc:0.589V, Jsc:35.6mA/cm2, F.E:0.763) with a cell size of 95.8cm2 and the thickness of 77μm. It is the highest efficiency ever reported for large area thin film Si solar cells.

Low Pressure Chemical Vapor Deposition of Tungsten and Aluminum for VLSI Applications

1986 ◽  
Vol 71 ◽  
Author(s):  
R. A. Levy ◽  
M. L. Green
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Chemical Vapor Deposition ◽  
Leakage Current ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Current Status ◽  
Tungsten Hexafluoride ◽  
Excess Surface ◽  
Pressure Chemical

AbstractThis paper reviews the current status of LPCVD tungsten and aluminum for VLSI applications. Using deposition chemistries based on tungsten hexafluoride and tri-isobutyl aluminum, W and Al deposits are characterized with respect to their electrical, mechanical, structural, chemical and optical properties. Although results of this study prove these two LPCVD processes to be compatible with current VLSI fabrication, certain problems must still be resolved for complete commercial acceptance. These problems include, in the case of selective LPCVD tungsten, the occurrence of leakage current across N+/P-Tub junctions, and in the case of LPCVD aluminum, the relatively poor electromigration resistance (compared to Al-Cu) and excess surface roughness.

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