Rayleigh Light Scattering Measurements of Transient Gas Temperature in a Rapid Chemical Vapor Deposition Reactor

1999 ◽  
Vol 122 (1) ◽  
pp. 165-170 ◽  
Author(s):  
J. F. Horton ◽  
J. E. Peterson
Keyword(s):  
Chemical Vapor Deposition ◽  
Light Scattering ◽  
Flow Field ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Gas Temperature ◽  
Wafer Temperature ◽  
Carrier Gas ◽  
Rayleigh Light Scattering ◽  
Rayleigh Light

A laser-induced Rayleigh light scattering (RLS) system was used to measure transient gas temperatures in a simulated rapid chemical vapor deposition (RCVD) reactor. The test section geometry was an axisymmetric jet of carrier gas directed down, impinging on a heated wafer surface. RLS was used to measure instantaneous gas temperature at several locations above the wafer as it was heated from room temperature to 475 K. Gas flow rate and wafer temperature correspond to jet Reynolds number Rei=60, wafer maximum Grashof number GrH=4.4×106, and maximum mixed convection parameter GrH/Rei2=1200; all conditions typical of impinging jet reactors common in the numerical literature. Uncertainty of RLS transient temperature from a propagated error analysis was ±2–4 K. Peak gas temperature fluctuations were large (in the order of 25 to 75 °C). Both flow visualization and RLS measurements showed that the flow field was momentum dominated prior to heating initiation, but became unstable by GrH/Rei2=5. It then consisted of buoyancy-induced plumes and recirculations. Up to the peak wafer temperature, the flow field continued to be highly three-dimensional, unsteady, and dominated by buoyancy. RLS measurements are shown to provide information on carrier gas instantaneous temperature and flow field stability, both critical issues in RCVD processing. [S0022-1481(00)02401-4]

Flow Regimes and Transitions in a Rapid Chemical Vapor Deposition Reactor Using Flow Visualization and Rayleigh Light Scattering

2000 ◽  
Author(s):  
Angelo G. Mathews ◽  
Jill E. Peterson
Keyword(s):  
Light Scattering ◽  
Flow Visualization ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Flow Regimes ◽  
Rayleigh Light Scattering ◽  
Flow Visualizations ◽  
Transition Points ◽  
Stable Flow ◽  
Rayleigh Light

Abstract Previous study of carrier gas flow in rapid chemical vapor deposition (RCVD) reactors has been limited mostly to numerical simulations and flow visualizations. In the present work flow regimes were observed and temperatures were measured in a vertical axisymmetric pedestal RCVD reactor using flow visualization and Rayleigh light scattering (RLS) for noninvasive temperature measurement. Flow visualizations revealed that the flow undergoes complex transitions between stable flow regimes as heating occurs. The two dominant stable flow regimes were buoyant stable (BS) and momentum stable (MS). RLS was used to determine the instantaneous carrier gas temperature at discrete points in the test section. The flow regimes and their transition points were easily recognized and agreed with flow visualization data. The flow visualizations and RLS tests showed identifiable trends in transition points between flow regimes and in the types of regimes encountered. These trends were dependent on Grashof number and Reynolds number.

Experimental Study of the Effect of Precursor Composition On the Microstructure of Gallium Nitride Thin Films Grown by the MOCVD Process

2021 ◽  
Author(s):  
Omar D. Jumaah ◽  
Yogesh Jaluria
Keyword(s):  
Thin Films ◽  
Gallium Nitride ◽  
Chemical Vapor Deposition ◽  
Deposition Rate ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Transport Processes ◽  
Carrier Gas ◽  
Precursor Composition

Abstract Chemical vapor deposition (CVD) is a widely used manufacturing process for obtaining thin films of materials like silicon, silicon carbide, graphene and gallium nitride that are employed in the fabrication of electronic and optical devices. Gallium nitride (GaN) thin films are attractive materials for manufacturing optoelectronic device applications due to their wide band gap and superb optoelectronic performance. The reliability and durability of the devices depend on the quality of the thin films. The metal-organic chemical vapor deposition (MOCVD) process is a common technique used to fabricate high-quality GaN thin films. The deposition rate and uniformity of thin films are determined by the thermal transport processes and chemical reactions occurring in the reactor, and are manipulated by controlling the operating conditions and the reactor geometrical configuration. In this study, the epitaxial growth of GaN thin films on sapphire (AL2O3) substrates is carried out in two commercial MOCVD systems. This paper focuses on the composition of the precursor and the carrier gases, since earlier studies have shown the importance of precursor composition. The results show that the flow rate of trimethylgallium (TMG), which is the main ingredient in the process, has a significant effect on the deposition rate and uniformity of the films. Also the carrier gas plays an important role in deposition rate and uniformity. Thus, the use of an appropriate mixture of hydrogen and nitrogen as the carrier gas can improve the deposition rate and quality of GaN thin films.

Omcvd Elaboration and Characterization of Silicon Carbide and Carbon-Silicon Carbide Films from Organosilicon Compounds

1992 ◽  
Vol 271 ◽  
Author(s):  
R. Morancho ◽  
A. Reynes ◽  
M'b. Amjoud ◽  
R. Carles
Keyword(s):  
Thin Films ◽  
Silicon Carbide ◽  
Raman Spectroscopy ◽  
Chemical Vapor Deposition ◽  
Thermal Behavior ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Organosilicon Compounds ◽  
Carrier Gas

ABSTRACTTwo organosilicon molecules tetraethysilane (TESi) and tetravinylsilane (TVSi) were used to prepare thin films of silicon carbide by chemical vapor deposition (C. V. D.). In each of the molecule, the ratio C/Si = 8, the only difference between TESi and TVSi is the structure of the radicals ethyl (.CH2-CH3) and vinyl (.CH=CH2). This feature induces different thermal behavior and leads to the formation of different materials depending on the nature of the carrier gas He or H2· The decomposition gases are correlated with the material deposited which is investigated by I.R. and Raman spectroscopy. The structure of the starting molecule influences the mechanisms of decomposition and consequently the structure of the material obtained.

The Utility of Laser Light Scattering in Assessing the Mixability of Reagents for Chemical Vapor Deposition

1993 ◽  
Vol 324 ◽  
Author(s):  
Bin Ni ◽  
Gene P. Reck ◽  
James W. Proscia
Keyword(s):  
Chemical Vapor Deposition ◽  
Light Scattering ◽  
Titanium Nitride ◽  
Tin Oxide ◽  
Vapor Deposition ◽  
Laser Light ◽  
Chemical Vapor ◽  
Reaction Chamber ◽  
Laser Light Scattering ◽  
Tin Oxide Films

AbstractThe premixability of reagents used in chemical vapor deposition reactors is important to insure that gas feed lines and nozzles do not become clogged with particulates during operation. Even if reactants are to be kept separate until introduced into a reaction chamber, it is desirable to limit the number of particles formed. A reactor which utilizes laser light scattering to monitor particulate formation when gaseous reagents are mixed is described. The reaction of tin (IV) chloride with water is commonly used to produce tin oxide films by chemical vapor deposition. It was found by the light scattering experiment that at temperatures above about 110°C the number of particulates formed is greatly reduced. Therefore, it would be most desirable that these reagents be mixed above this temperature when depositing tin oxide from this reaction. The reaction of titanium tetrachloride with various amine was also investigated by this method. This reaction has been demonstrated to produce titanium nitride above 450°C. For each case, it was observed that there was a temperature above which the number of particulates was significantly reduced. This temperature was always below the optimal temperature for producing titanium nitride films.

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