The Effects of Collimator Life Time on the Ti and Tin Film Growth Rates and Conformalities in Sputter Deposition Processes: Experiments and Simulations

1995 ◽  
Vol 387 ◽  
Author(s):  
Hung Liao ◽  
Hannes Stippel ◽  
Krishna Reddy ◽  
Sam Geha ◽  
Kevin Brown ◽  
...  
Keyword(s):  
Growth Rates ◽  
Film Growth ◽  
Side Wall ◽  
Life Time ◽  
Deposition Process ◽  
Sputter Deposition ◽  
Cross Sectional ◽  
Tin Film ◽  
Side Walls ◽  
Deposition Processes

AbstractExperimental and simulation studies were conducted in an attempt to understand the effects of collimator life time on the Ti and TiN film growth rates and conformalities in sputter deposition processes. The Ti and TiN films were deposited with and without collimation. The hexagonal cells of the collimator used in this study have a 1:1 aspect ratio. A Monte Carlo based simulator was used to calculate the angular distributions of species exiting from a collimator cell and the percentage decrease in the rate of film growth as a function of the collimator life time. Then, a low pressure deposition process simulator, EVOLVE, was used to predict the conformalities of deposited films in contacts or vias, assuming that the films were uniformly deposited on the side-walls of collimator cells. We conclude that the loss in growth rate is largely due to the shrinkage in the cross sectional area of the collimator cell inlets. We arrive at this conclusion after comparing an estimated film thickness on the collimator side-walls with experimental measurements. With extended collimator usage, the predicted and experimental film profiles in contacts or vias show increasing bottom coverage and decreasing side-wall coverages.

The Effects of Collimator Life Time on the Ti and Tin Film Growth Rates and Conformalities in Sputter Deposition Processes: Experiments and Simulations

1995 ◽  
Vol 389 ◽  
Author(s):  
Hung Liao ◽  
Hannes Stippel ◽  
Krishna Reddy ◽  
Sam Geha ◽  
Kevin Brown ◽  
...  
Keyword(s):  
Growth Rates ◽  
Film Growth ◽  
Side Wall ◽  
Life Time ◽  
Deposition Process ◽  
Sputter Deposition ◽  
Cross Sectional ◽  
Tin Film ◽  
Side Walls ◽  
Deposition Processes

ABSTRACTExperimental and simulation studies were conducted in an attempt to understand the effects of collimator life time on the Ti and TiN film growth rates and conformalities in sputter deposition processes. The Ti and TiN films were deposited with and without collimation. The hexagonal cells of the collimator used in this study have a 1:1 aspect ratio. A Monte Carlo based simulator was used to calculate the angular distributions of species exiting from a collimator cell and the percentage decrease in the rate of film growth as a function of the collimator life time. Then, a low pressure deposition process simulator, EVOLVE, was used to predict the conformalities of deposited films in contacts or vias, assuming that the films were uniformly deposited on the side-walls of collimator cells. We conclude that the loss in growth rate is largely due to the shrinkage in the cross sectional area of the collimator cell inlets. We arrive at this conclusion after comparing an estimated film thickness on the collimator side-walls with experimental measurements. With extended collimator usage, the predicted and experimental film profiles in contacts or vias show increasing bottom coverage and decreasing side-wall coverages.

scholarly journals Sputter Deposition of Semiconductor Superlattices for Thermoelectric Applications

1996 ◽  
Vol 450 ◽  
Author(s):  
Andrew V. Wagner ◽  
Ronald J. Foreman ◽  
Joseph C. Farmer ◽  
Troy W. Barbee
Keyword(s):  
Film Growth ◽  
Lead Telluride ◽  
Deposition Process ◽  
Growth Conditions ◽  
Sputter Deposition ◽  
High Rate ◽  
Dramatic Improvement ◽  
High Deposition Rate ◽  
High Quality ◽  
Quantum Confined

ABSTRACTTheoretical dramatic improvement of the thermoelectric properties of materials by using quantum confinement in novel semiconductor nanostructures has lead to considerable interest in the thermoelectric community. Therefore, we are exploring the critical materials issues for fabrication of quantum confined structures by magnetron sputtering in the lead telluride and bismuth telluride families of materials. We have synthesized modulated structures from thermoelectric materials with bilayer periods of as little as 3.2 nm and shown that they are stable at deposition temperatures high enough to grow quality films. Issues critical to high quality film growth have been investigated such as nucleation and growth conditions and their effect on crystal orientation and growth morphology. These investigations show that nucleating the film at a temperature below the growth temperature of optimum electronic properties produces high quality films. Our work with sputter deposition, which is inherently a high rate deposition process, builds the technological base necessary to develop economical production of these advanced materials. High deposition rate is critical since, even if efficiencies comparable with CFC based refrigeration systems can be achieved, large quantities of quantum confined materials will be necessary for cost-competitive uses.

Boussinesq solution for solitary waves in uniform channels with sloping side walls

2000 ◽  
Vol 214 (6) ◽  
pp. 781-787 ◽  
Author(s):  
M H Teng
Keyword(s):  
Solitary Waves ◽  
Small Amplitude ◽  
Wave Speed ◽  
Side Wall ◽  
Boussinesq Equations ◽  
Wave Profile ◽  
Cross Sectional ◽  
Side Walls ◽  
Boussinesq Solution ◽  
Wall Slope

The analytical solution to the Boussinesq equations for solitary waves travelling in uniform water channels with sloping side walls is presented. Quantitative effects of channel cross-sectional geometry and channel side-wall slope at the waterline on the wave profile and wave speed, as well as the criteria for positive solitary waves to exist, are discussed. The new Boussinesq solution is also compared with the existing Korteweg-de Vries solution obtained by Peregrine. It is found that the two solutions are consistent for small amplitude waves while, for relatively large waves, the Boussinesq solution gives different predictions for wave speed and for the criteria for solitary waves to exist.

Lateral/vertical Homoepitaxial Growth on 4H-SiC Surfaces Controlled by Dislocations

2008 ◽  
Vol 1069 ◽  
Author(s):  
Yoosuf N. Picard ◽  
Andrew J. Trunek ◽  
Philip G. Neudeck ◽  
Mark E. Twigg
Keyword(s):  
Film Growth ◽  
Electron Backscatter Diffraction ◽  
Side Wall ◽  
Chemical Vapor ◽  
Film Structure ◽  
Atomic Step ◽  
Contrast Imaging ◽  
Screw Dislocations ◽  
Side Walls ◽  
Backscatter Diffraction

ABSTRACTThis paper reports the influence of screw dislocations on the lateral/vertical growth behavior of chemical vapor deposited (CVD) on-axis homoepitaxial 4H-SiC films grown on patterned mesas. Electron channeling contrast imaging (ECCI) was utilized to image both atomic steps and dislocations while the film structure/orientation was determined using electron backscatter diffraction (EBSD). The presence and position of screw dislocations within the mesa impacted the resultant film thickness, lateral shape, and atomic step morphology. Mesa side walls that incline inwards due to faceting during screw-dislocation driven vertical film growth can intersect with the dislocation step sources near the side walls. If this occurs for all screw dislocations on a mesa, we observe a transition towards laterally dominated growth that produces webbed structures and films surfaces exhibiting significantly lower step densities. Transition from vertical to lateral dominated growth is consistent with ECCI imaged dislocation very near a mesa side wall.

Polycrystalline β-SiC Film Growth on Si by ECR-CVD at 178 - 500°C

1995 ◽  
Vol 403 ◽  
Author(s):  
Kuan-Lun Cheng ◽  
Chih-Chien Liu ◽  
Chung-Min Fu ◽  
Huang-Chung Cheng ◽  
Chiapyng Lee ◽  
...  
Keyword(s):  
Electron Cyclotron Resonance ◽  
Film Growth ◽  
Film Surface ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Dark Field ◽  
Cross Sectional ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Field Imaging

AbstractPolycrystalline β-SiC, with grain size up to 0.2 μm, was grown on silicon substrate by electron cyclotron resonance chemical vapor deposition (ECR-CVD) from SiH4/CH4/H2 at 178–500 °C. The nucleation process and surface structure of polycrystalline SiC were investigated via observing the film surface by atomic force microscopy (AFM). Reaction species which promote polycrystalline SiC was in-situ monitored by quadruple mass spectrum analysers during deposition process, which is crucial for the control of polycrystalline SiC growth. The microstructure of SiC films were inspected by bright-field imaging, dark-field imaging, and electron diffraction in cross-sectional transmission electron microscopy. This paper will also discuss the key parameters for the nucleation and growth of polycrystalline β-SiC at very low temperature in ECR-CVD system.

Chemical vapor deposition of titanium nitride thin films from tetrakis(dimethylamido)titanium and hydrazine as a coreactant

2000 ◽  
Vol 15 (11) ◽  
pp. 2414-2424 ◽  
Author(s):  
Carmela Amato-Wierda ◽  
Derk A. Wierda
Keyword(s):  
Thin Films ◽  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Growth Rates ◽  
Vapor Deposition ◽  
Film Growth ◽  
Chemical Vapor ◽  
Air Exposure ◽  
Tin Films ◽  
Tin Film

Hydrazine was used as a coreactant with tetrakis(dimethylamido)titanium for the low-temperature chemical vapor deposition of TiN between 50 and 200 °C. The TiN film-growth rates ranged from 5 to 45 nm/min. Ti:N ratios of approximately 1:1 were achieved. The films contain between 2 and 25 at.% carbon, as well as up to 36 at.% oxygen resulting from diffusion after air exposure. The resistivity of these films is approximately 104 μΩ cm. Annealing the films in ammonia enhances their crystallinity. The best TiN films were produced at 200 °C from a 2.7% hydrazine–ammonia mixture. The Ti:N ratio of these films is approximately 1:1, and they contain no carbon or oxygen. These films exhibit the highest growth rates observed.

Pt Film Growth with Tetra-Kis(Triflurophosphine)Platinum

1999 ◽  
Vol 596 ◽  
Author(s):  
Y.-M. Sun ◽  
J. Lozano ◽  
N. Mettlach ◽  
J. G. Ekerdt ◽  
S. Madhukar ◽  
...  
Keyword(s):  
Growth Rate ◽  
Silicon Oxide ◽  
Film Growth ◽  
Side Wall ◽  
Initial Growth ◽  
Lower Growth ◽  
Cross Sectional ◽  
Initial Growth Rate ◽  
Step Coverage ◽  
Wide Range

AbstractPlatinum film growth using Pt(PF3)4 precursors was investigated. The study focused on three aspects of film growth: conformality, adhesion and selective growth. Pt(PF3)4 deposited pure Pt films over a wide range of temperatures (∼200 to 400 °C). At 200 °C, the step coverage for a via with an aspect ratio of three was poor. Lower growth temperatures showed a significant decrease in the growth rate. In addition, these films had poor adhesion to the substrate as indicated by separation between the Pt and the substrate in cross sectional scanning electron microscopy images. Oxygen addition during Pt film growth from Pt(PF3)4 improved both film conformality and adhesion. With oxygen, the step coverage on the side wall was greater than 90 % The dependence of the film growth rate on oxygen varied with the growth temperature: the growth rate decreased at 200 °C, while it changed slightly at 260 °C when oxygen was added. The substrate effect on the initial growth rate was studied on various substrates. The initial growth rate on metals is much faster than that on other substrates. The growth rate decreased on various substrates in the order of iridium > titanium nitride > barium strontium titanate > silicon nitride > silicon oxide.

Assessment of knowledge and practice of vaccination of dogs against rabies by dog owners in Makurdi, Benue State, Nigeria

2020 ◽  
Vol 1 ◽  
pp. 5
Author(s):  
Audu Onyemocho ◽  
Agwa Moses ◽  
Aboh Kisani ◽  
Omole Namben Victoria ◽  
Anejo-Okopi Joseph
Keyword(s):  
Low Income ◽  
Life Time ◽  
Knowledge Score ◽  
Educational Status ◽  
Low Income Countries ◽  
Bivariate Analysis ◽  
Cross Sectional ◽  
Knowledge And Practice ◽  
Dog Owners ◽  
The Relationship

Objective: Rabies, one of the oldest and fatal infectious diseases known to human race, is transmitted by infected dogs. The global target of zero dog-mediated rabies human deaths has been set for 2030; however, the realization of this goal poses challenges in most low-income countries where rabies is endemic due to weak surveillance. Dogs have been increasingly deployed for domestic uses over the years, especially for security purposes. This study assessed the assessment of knowledge and practice of vaccination of dogs against rabies by dog owners. Materials and Methods: A cross-sectional community-based study was employed to study 400 dog owners in Makurdi metropolis through multistage sampling techniques. Sighting of valid dog vaccination card was used as criteria for current vaccination. Bivariate analysis was carried out to establish the relationship between the respondent knowledge of rabies and dog vaccination with significant value set at P < 0.05. Results: The mean age of the respondents was 31 (Â ± 0.8) years, majority of them had tertiary and secondary education (40.0% and 39.0%, respectively), 26.0% were traders, and 50.0% were married. Overall, 73.0% of the respondents had good knowledge score, 61.0% had seen at least a rabid dog in their life time, and 74.0% have a history of dog vaccination, but evidence of up to date vaccination of dogs by owners was seen in only 18.0% of all the vaccination cards sighted. The relationship between the educational status of the respondents, their knowledge score, and their dog vaccination was statistically significant (P < 0.05). Conclusion: Knowledge of rabies among dog owners in Makurdi was good, but the practice of dog vaccination was poor. Educational status was a good predictor of practice. Awareness campaign on dog vaccination should be strengthened and adequate measures should be put in place at the veterinary hospitals in Makurdi for vaccination of dogs.

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