Suppression of Buoyancy in a Prototypical CVD Reactor by Geometry Modification

2003 ◽  
Author(s):  
S. P. Vanka ◽  
Gang Luo ◽  
Nick G. Glumac
Keyword(s):  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Flow Patterns ◽  
Film Deposition ◽  
Stagnation Flow ◽  
Complex Flow ◽  
Azimuthal Symmetry ◽  
New Type ◽  
High Degree

Buoyancy plays a detrimental role in chemical vapor deposition reactors employed for thin film deposition. Buoyancy driven fluid flow causes complex flow patterns which alter the transport of the precursor gases to the substrate, and leads to nonuniform deposition patterns. Consequently, many CVD reactors operate under low pressure to mitigate these flow patterns. However, the growth rates at such pressures are relatively low. Operating a CVD reactor under vacuum conditions is also inconvenient because of the associated hardware that is required. In the present work, we have numerically explored the performance of a new type of stagnation flow CVD reactor at pressures close to atmospheric pressure. The new geometry resembles that of a pancake reactor, but the gases are supplied through a long vertical inlet. The annular wall above the substrate is maintained at a low temperature to avoid deposition on this surface. The substrate is also rotated to improve the hydrodynamic patterns and provide azimuthal symmetry. We report results of a number of high-resolution calculations in this reactor to demonstrate its merits for operation at sub-atmospheric and atmospheric pressures. It is shown that the growth rate is significantly large, in addition to a high degree of film uniformity.

A New Type of Cluster-Ion Source for Thin Film Deposition

1990 ◽  
Vol 206 ◽  
Author(s):  
Hellmut Haberland ◽  
Martin Karrais ◽  
Martin Mall
Keyword(s):  
Electron Impact ◽  
Plane Surface ◽  
Thin Film Deposition ◽  
Ion Source ◽  
Film Deposition ◽  
Cluster Ions ◽  
Cluster Ion ◽  
Impact Ionisation ◽  
Aggregation Technique ◽  
High Degree

ABSTRACTAtoms are gas discharge sputtered from a solid target. They are condensed to form clusters using the gas aggregation technique. An intense beam of clusters of all solid materials can be obtained. Up to 80 % of the clusters can be ionised without using additional electron impact ionisation. Total deposition rates vary between 1 and 1000 Å per second depending on cluster diameter, which can be varied between 3 and 500 nm. Thin films of Al, Cu, and Mo have been produced so far. For non accelerated beams a weakly adhering mostly coulored deposit is obtained. Accelerating the cluster ions this changes to a strongly adhering film, having a shiny metallic appearance, and a very sharp and plane surface as seen in an electron microscope. The advantages compared to Kyoto ICB-method are: easy control of the cluster size, no electron impact ionisation, high degree of ionisation, and sputtering is used instead of thermal evaporation, which allows the use of high melting point materials.

Developing Monolithically Integrated CdTe Devices Deposited by AP-MOCVD

2013 ◽  
Vol 1538 ◽  
pp. 275-280
Author(s):  
S.L. Rugen-Hankey ◽  
V. Barrioz ◽  
A. J. Clayton ◽  
G. Kartopu ◽  
S.J.C. Irvine ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Thin Film Deposition ◽  
Deposition Process ◽  
Film Deposition ◽  
Aluminosilicate Glass ◽  
Organic Chemical ◽  
Large Area ◽  
Monolithically Integrated ◽  
Glass Substrates ◽  
Laser Scribing

ABSTRACTThin film deposition process and integrated scribing technologies are key to forming large area Cadmium Telluride (CdTe) modules. In this paper, baseline Cd1-xZnxS/CdTe solar cells were deposited by atmospheric-pressure metal organic chemical vapor deposition (AP-MOCVD) onto commercially available ITO coated boro-aluminosilicate glass substrates. Thermally evaporated gold contacts were compared with a screen printed stack of carbon/silver back contacts in order to move towards large area modules. P2 laser scribing parameters have been reported along with a comparison of mechanical and laser scribing process for the scribe lines, using a UV Nd:YAG laser at 355 nm and 532 nm fiber laser.

Atmospheric Pressure Low Temperature Direct Plasma Technology: Status and Challenges for Thin Film Deposition

2012 ◽  
Vol 9 (11-12) ◽  
pp. 1041-1073 ◽  
Author(s):  
Francoise Massines ◽  
Christian Sarra-Bournet ◽  
Fiorenza Fanelli ◽  
Nicolas Naudé ◽  
Nicolas Gherardi
Keyword(s):  
Thin Film ◽  
Low Temperature ◽  
Atmospheric Pressure ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Plasma Technology

Flow Structure and Heat Transfer in Stagnation Flow CVD Reactor

2010 ◽  
Author(s):  
Nasir Memon ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Design Parameters ◽  
Stagnation Flow ◽  
Inlet Length ◽  
The Impact

An experimental study is undertaken to investigate the flow structure and heat transfer in a stagnation flow Chemical Vapor Deposition (CVD) reactor at atmospheric pressure. It is critical to develop models that predict flow patterns in such a reactor to achieve uniform deposition across the substrate. Free convection can negatively affect the gas flow as cold inlet gas impinges on the heated substrate, leading to vortices and disturbances in the normal flow path. This experimental research will be used to understand the buoyancy-induced and momentum-driven flow structure encountered in an impinging jet CVD reactor. Investigations are conducted for various operating and design parameters. A modified stagnation flow reactor is built where the height between the inlet and substrate is reduced when compared to a prototypical stagnation flow reactor. By operating such a reactor at certain Reynolds and Grashof numbers it is feasible to sustain smooth and vortex free flow at atmospheric pressure. The modified stagnation flow reactor is compared to other stagnation flow geometries with either a varied inlet length or varied heights between the inlet and substrate. Comparisons are made to understand the impact of such geometric changes on the flow structure and the thermal boundary layer. In addition, heat transfer correlations are obtained for the substrate temperature. Overall, the results obtained provide guidelines for curbing the effects of buoyancy and for improving the flow field to obtain greater film uniformity when operating a stagnation flow CVD reactor at atmospheric pressure.

Radio frequency expanding plasmas at low, intermediate, and atmospheric pressure and their applications

2008 ◽  
Vol 80 (9) ◽  
pp. 1919-1930 ◽  
Author(s):  
Gheorghe Dinescu ◽  
Eusebiu R. Ionita
Keyword(s):  
Radio Frequency ◽  
Atmospheric Pressure ◽  
Thin Film Deposition ◽  
Plasma Jets ◽  
Film Deposition ◽  
High Mass ◽  
Rf Plasma ◽  
Temperature Sensitive ◽  
Large Size ◽  
Wide Range

We report on the operation and characteristics of radio frequency (RF) plasma beam sources based on the expansion of the discharge outside of limited spaces with small interelectrode gaps. The appropriate electrode configuration, combined with high mass flow values and appropriate power levels, leads to small- or large-size plasma jets, working stably at low, intermediate, and atmospheric pressures. The sources are promising tools for a wide range of applications in thin film deposition, surface modification, and cleaning, including the case of temperature-sensitive substrates.

Emission spectra study of plasma enhanced chemical vapor deposition of intrinsic, n+, and p+ amorphous silicon thin films

2013 ◽  
Vol 1536 ◽  
pp. 133-138
Author(s):  
I-Syuan Lee ◽  
Yue Kuo
Keyword(s):  
Deposition Rate ◽  
Gas Flow ◽  
Emission Spectra ◽  
Chemical Vapor ◽  
Critical Factor ◽  
Optical Emission ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Silicon Thin Films ◽  
Deposition Processes

ABSTRACTThe PECVD intrinsic, n+, and p+ a-Si:H thin film deposition processes have been studied by the optical emission spectroscope to monitor the plasma phase chemistry. Process parameters, such as the plasma power, pressure, and gas flow rate, were correlated to SiH*, Hα*, and Hβ* optical intensities. For all films, the deposition rate increases with the increase of the SiH* intensity. For the doped films, the Hα*/SiH* ratio is a critical factor affecting the resistivity. The existence of PH3 or B2H6 in the feed stream enhances the deposition rate. Changes of the free radicals intensities can be used to explain variation of film characteristics under different deposition conditions.

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