Kinetics of Chemical Vapor Deposition of Sic Between 750 and 850°C at 1 Bar Total Pressure

1991 ◽  
Vol 250 ◽  
Author(s):  
Dieter Neuschütz ◽  
Farzin Salehomoum
Keyword(s):  
Deposition Rate ◽  
Total Pressure ◽  
Reaction Rate ◽  
Chemical Vapor ◽  
Deposition Mechanism ◽  
Reaction Orders ◽  
Si Content ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Kinetics Of

AbstractThe deposition rate from mixtures of methyltrichlorosilane (MTS), hydrogen and methane was measured thermogravimetrically using a hot wall vertical reactor and planar SiC substrates. Below 850 °C and at sufficiently high gas velocities, the rate of the phase boundary reaction could be determined. In the absence of CH4 and at H2 :MTS=55, Si was deposited together with SiC. Addition of CH4 lowered the Si content, pure SiC being deposited at CH4 :MTS above 10. The deposition rate j in the range 750 to 850 °C follows the equation with E(Si) = 160 and E(SiC) = 300 kJ/mol. Reaction mechanisms are presented to account for the observed reaction orders with respect to MTS. Between 900 and 970 °C, the reaction rate decreased with temperature indicating a change in the deposition mechanism.

Deposition Mechanism of Tungsten Silicide Films by Low Pressure CVD

1990 ◽  
Vol 181 ◽  
Author(s):  
Jae H. Sone ◽  
Hyeong J. Kim
Keyword(s):  
Mass Transfer ◽  
Deposition Rate ◽  
Flow Rate ◽  
Deposition Temperature ◽  
Gas Flow ◽  
Chemical Vapor ◽  
Low Pressure ◽  
Deposition Mechanism ◽  
Si Substrates ◽  
Si Content

ABSTRACTWSix thin films were deposited on SiO2/Si substrates by Low Pressure Chemical Vapor Deposition (LPCVD) using WF6 and SiH4 gases. The deposition mechanism has been studied by measuring the thickness, resistivity and composition of the films by varying deposition temperature and gas flow rate at a constant total reactant gas pressure. Below 300°C, the surface chemical reaction was the rate-limiting process and the deposition rate increased exponentially with temperature having a thermal activation energy of 3.2 kcal/mol. Meanwhile, above 300°C the reaction was governed by the mass transfer step in the gas. The deposition rate in this range is insensitive to the deposition temperature but shows dependence of the flow rate of reactant gases. AES and RBS analyses were performed to determine the stoichiometry of WSix thin film. The Si content in film gradually increased as the deposition temperature increased. The resistivity of as-deposited WSix film has dependence on both deposition temperature and Si/W ratio, and exponentially increased with a moderate slope. However, temperature insensitive behavior of resistivity appeared in the mass transfer controlled region. Such resistivity changes with temperature were discussed with the Si/W ratio and the microstructure of films.

scholarly journals Deposition Kinetics of Thin Silica-Like Coatings in a Large Plasma Reactor

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3238 ◽  
Author(s):  
Žiga Gosar ◽  
Denis Đonlagić ◽  
Simon Pevec ◽  
Janez Kovač ◽  
Miran Mozetič ◽  
...  
Keyword(s):  
Deposition Rate ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Processing Parameters ◽  
Ion Density ◽  
Capacitively Coupled ◽  
Rotary Pumps ◽  
Kinetics Of ◽  
Radio Frequency Discharge ◽  
Deposited Films

An industrial size plasma reactor of 5 m3 volume was used to study the deposition of silica-like coatings by the plasma-enhanced chemical vapor deposition (PECVD) method. The plasma was sustained by an asymmetrical capacitively coupled radio-frequency discharge at a frequency of 40 kHz and power up to 7 kW. Hexamethyldisilioxane (HMDSO) was introduced continuously at different flows of up to 200 sccm upon pumping with a combination of roots and rotary pumps at an effective pumping speed between 25 and 70 L/s to enable suitable gas residence time in the plasma reactor. The deposition rate and ion density were measured continuously during the plasma process. Both parameters were almost perfectly constant with time, and the deposition rate increased linearly in the range of HMDSO flows from 25 to 160 sccm. The plasma density was of the order of 1014 m−3, indicating an extremely low ionization fraction which decreased with increasing flow from approximately 2 × 10−7 to 6 × 10−8. The correlations between the processing parameters and the properties of deposited films are drawn and discussed.

Kinetic Study on Microwave Magnetizing Roast of Fe2O3 Powders

2020 ◽  
Vol 304 ◽  
pp. 91-97
Author(s):  
Lei Wang ◽  
Ling Bing Kong ◽  
Pei Min Guo ◽  
Jie Li
Keyword(s):  
Reaction Rate ◽  
Reaction Kinetic ◽  
Three Dimensional ◽  
Kinetic Mechanism ◽  
Electrical Heating ◽  
Diffusion Control ◽  
Weight Loss Curve ◽  
Dimensional Diffusion ◽  
Boundary Reaction ◽  
Phase Boundary Reaction

In this paper, the reaction kinetic mechanism of Fe2O3 powder containing carbon was studied by microwave magnetizing roast. Based on the temperature-rise curve and weight loss curve of Fe2O3 powder by microwave magnetizing roast, the kinetic parameters of Fe2O3 powder microwave magnetizing roast were calculated by non-isothermal methods. The controlling steps of different temperature-rising periods in microwave magnetizing roast process of Fe2O3 powder were calculated by the Achar-Brindley-Sharp-Wendworth method. The results indicated that the controlling step of microwave magnetizing roast was phase boundary reaction control of contracted cylinder in 250~450°C, and it was three-dimensional diffusion control of spherical symmetry in 450~650°C. The results showed that the starting temperature of reduction roasting of Fe2O3 powder was 250°C, which was lower than that under electrical heating, thereby, it proved in theory that microwave heating can enhance reaction rate.

Synthesis and Determination of the Kinetic Parameters for Non-Isothermal Decomposition of Complexes Ln(thd)3phen

2006 ◽  
Vol 530-531 ◽  
pp. 506-512 ◽  
Author(s):  
Wilton Silva Lopes ◽  
Crislene Rodrigues da Silva Morais ◽  
A.G. de Souza
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Lanthanide Complexes ◽  
Reaction Order ◽  
Decomposition Reaction ◽  
Cylindrical Symmetry ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Kinetics Of

In this work the kinetics of the thermal decomposition of two ß-diketone lanthanide complexes of the general formula Ln(thd)3phen (where Ln = Nd+3 or Tm+3, thd = 2,2,6,6- tetramethyl-3,5-heptanodione and phen = 1,10-phenantroline) has been studied. The powders were characterized by several techniques. Thermal decomposition of the complexes was studied by non-isothermal thermogravimetry techniques. The kinetic model that best describes the process of the thermal decomposition of the complexes it was determined through the method proposed by Coats-Redfern. The average values the activation energy obtained were 136 and 114 kJ.mol-1 for the complexes Nd(thd)3phen and Tm(thd)3phen, respectively. The kinetic models that best described the thermal decomposition reaction the both complexes were R2. The model R2 indicating that the mechanism is controlled by phase-boundary reaction (cylindrical symmetry) and is defined by the function g(α) = 2[1-(1-a)1/2], indicating a mean reaction order. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen > Tm(thd)3phen.

Growth kinetics of chemically vapor deposited SiO2 films from silane oxidation

1998 ◽  
Vol 13 (8) ◽  
pp. 2308-2314 ◽  
Author(s):  
Fernando Ojeda ◽  
Alejandro Castro-García ◽  
Cristina Gómez-Aleixandre ◽  
José María Albella
Keyword(s):  
Gas Phase ◽  
Deposition Rate ◽  
Growth Kinetics ◽  
Film Growth ◽  
Chemical Vapor ◽  
Intermediate Species ◽  
Pressure Oxygen ◽  
Pressure Chemical ◽  
Different Temperatures ◽  
Kinetics Of

The growth kinetics of SiO2 thin films obtained by low-pressure chemical vapor deposition (CVD) from SiH4/O2/N2 gas mixtures has been determined at different temperatures and flow rates. The results show that the film growth is originated by some intermediate species (e.g., SiOxHy) produced in the gas phase. At low temperatures the deposition rate is limited by some homogeneous reaction with an apparent activation energy of 1.42 eV. Furthermore, the observation of critical limits when total pressure, oxygen/silane flow ratio, and temperature are decreased gives support to a branching-chain mechanism of deposition. Finally, we have observed that the deposition rate shows a hysteresis behavior when varying the temperature within the 300–400 °C range, which has been attributed to the inhibition of silane oxidation by the Si–OH surface groups of the films grown on the reactor walls.

Highly (004)-Oriented Texture of γ-LiAlO2 Films by Laser Chemical Vapor Deposition

2014 ◽  
Vol 616 ◽  
pp. 141-144
Author(s):  
Chen Chi ◽  
Hirokazu Katsui ◽  
Rong Tu ◽  
Takashi Goto
Keyword(s):  
Chemical Vapor Deposition ◽  
Deposition Rate ◽  
Vapor Deposition ◽  
Total Pressure ◽  
Deposition Temperature ◽  
Chemical Vapor ◽  
Columnar Structure ◽  
Molar Ratio ◽  
Laser Chemical Vapor Deposition ◽  
Oriented Texture

(004)-oriented γ-LiAlO2films were prepared on poly-crystalline AlN substrates by laser chemical vapor deposition at deposition temperature (Tdep) of 1100–1250 K, molar ratio of Li/Al (RLi/Al) of 1.0–10 and low total pressure (Ptot) of 100–200 Pa. The (004)-oriented γ-LiAlO2films consisted of pyramidal grains with a columnar structure. The deposition rate of (004)-oriented γ-LiAlO2films reached to 65–72 μm h-1.

Growth kinetics of ZnO prepared by organometallic chemical vapor deposition

1988 ◽  
Vol 3 (4) ◽  
pp. 740-744 ◽  
Author(s):  
P. Souletie ◽  
B. W. Wessels
Keyword(s):  
Growth Kinetics ◽  
Deposition Temperature ◽  
Reaction Rate ◽  
Surface Reaction ◽  
Chemical Vapor ◽  
Auger Spectroscopy ◽  
X Ray ◽  
Zinc Oxide Films ◽  
Complex Temperature ◽  
Kinetics Of

Zinc oxide films were deposited using the reactants dimethyl zinc and tetrahydrofuran. Growth kinetics were determined from the dependence of the growth rate on substrate temperature and reactant partial pressure. A complex temperature dependence was observed over the temperature range of 300–500 °C. For a deposition temperature of 400 °C, the growth kinetics were modeled using a bimolecular surface reaction rate-limited mechanism. The layers were characterized using x-ray diffractometer and Auger spectroscopy measurements.

Decomposition of BrO studied by kinetic spectroscopy

1970 ◽  
Vol 48 (22) ◽  
pp. 3487-3490 ◽  
Author(s):  
J. Brown ◽  
George Burns
Keyword(s):  
Activation Energy ◽  
Total Pressure ◽  
Reaction Rate ◽  
Second Order ◽  
Kcal Mole ◽  
Kinetic Spectroscopy ◽  
Reaction Proceeds ◽  
One Step ◽  
Kinetics Of ◽  
Activated Complex

Kinetics of BrO decomposition was studied between 293 and 673 °K using the technique of kinetic spectroscopy. At 293 °K the reaction rate is second order with respect to BrO and is independent of [Br2], [O2], and total pressure of diluent gas. The activation energy for decomposition obtained from rate measurements between 293 and 450 °K is 0.65 ± 0.05 kcal/mole. Above 450 °K this activation energy appears to increase to 4.5 kcal/mole. It is shown that, although kinetically the ClO and BrO decompositions are similar, the mechanism for BrO decomposition below 450 °K is much simpler than that of ClO. The reaction proceeds, most likely, via one step: 2 BrO → 2 Br + O2, with Br2O2 being an activated complex, which has either linear or staggered configuration. ClO and BrO decomposition is compared with [Formula: see text] reaction.

Die Kinetik und der Mechanismus der thermischen Reaktion zwischen Schwefeltetrafluorid und Fluor / The Kinetics and the Mechanism of the Thermal Reaction between Sulfurtetrafluoride and Fluorine

1981 ◽  
Vol 36 (11) ◽  
pp. 1381-1385 ◽  
Author(s):  
Alicia Cristina Gonzalez ◽  
Hans Joachim Schumacher
Keyword(s):  
Chain Length ◽  
Total Pressure ◽  
Reaction Rate ◽  
Thermal Reaction ◽  
Primary Process ◽  
Chain Reaction ◽  
Experimental Conditions ◽  
Medium Length ◽  
A Chain ◽  
Kinetics Of

AbstractThe kinetics of the thermal reaction between SF4 and F2 has been investigated between − 2.4 °C and + 24.0 °C, SF6 and very small amounts of S2F10 being the only products. The reaction is a chain reaction of medium length. Total pressure and surface have only insignificant influence. The reaction rate follows the equation: Under the experimental conditions less than 15% of the SF5 radicals are consumed by r (4b). Therefore Oxygen inhibits the reaction eliminating the SF5 radicals, the final products being now SF5O3SF5 and SF6. From the data obtained in the experiments with high oxygen pressures the rate constant of the primary process and the chain length (v) are determined. E = 10.8 ± 0.7 kcal, E1 = 11.9 ± 0.6 kcal and E4 ≃ 0. E2 = 5.0 ± 2.0 kcal (estimated value) and E3 = 4.7 ± 2.5 kcal.

scholarly journals Structural Controlling of Highly-Oriented Polycrystal 3C-SiC Bulks via Halide CVD

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 390 ◽  
Author(s):  
Zhiying Hu ◽  
Dingheng Zheng ◽  
Rong Tu ◽  
Meijun Yang ◽  
Qizhong Li ◽  
...  
Keyword(s):  
Total Pressure ◽  
Molten Aluminum ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Deposition Mechanism ◽  
Growth Orientation ◽  
Vacuum Atmosphere ◽  
Columnar Grains ◽  
Surface Morphologies ◽  
Wetting Behaviors

Highly-oriented polycrystal 3C-SiC bulks were ultra-fast fabricated via halide chemical vapor deposition (CVD) using tetrachlorosilane (SiCl4) and methane (CH4) as precursors. The effects of deposition temperature (Tdep) and total pressure (Ptot) on the orientation and surficial morphology were investigated. The results showed that the growth orientation of 3C-SiC columnar grains was strongly influenced by Tdep. With increasing Tdep, the columnar grains transformed from <111>- to <110>-oriented. The arrangement of <111>-oriented columnar grains was controlled by Ptot. Lotus-, turtle-, thorn-, and strawberry-like surface morphologies were naturally contributed by different arrangements of <111>-oriented grains, and the deposition mechanism was discussed. The wetting behaviors of CVD-SiC samples by molten aluminum were also examined at 1173 K in a high vacuum atmosphere.

Sign in / Sign up

Export Citation Format

Share Document