Value Of Sticking Coefficient Research Articles

A novel fast and flexible technique of radical kinetic behaviour investigation based on pallet for plasma evaluation structure and numerical analysis

This paper describes a new, fast, and case-independent technique for sticking coefficient (SC) estimation based on pallet for plasma evaluation (PAPE) structure and numerical analysis. Our approach does not require complicated structure, apparatus, or time-consuming measurements but offers high reliability of data and high flexibility. Thermal analysis is also possible. This technique has been successfully applied to estimation of very low value of SC of hydrogen radicals on chemically amplified ArF 193 nm photoresist (the main goal of this study). Upper bound of our technique has been determined by investigation of SC of fluorine radical on polysilicon (in elevated temperature). Sources of estimation error and ways of its reduction have been also discussed. Results of this study give an insight into the process kinetics, and not only they are helpful in better process understanding but additionally they may serve as parameters in a phenomenological model development for predictive modelling of etching for ultimate CMOS topography simulation.

Conformal Polymeric Thin Films by Low-Temperature Rapid Initiated Chemical Vapor Deposition (iCVD) Using tert-Butyl Peroxybenzoate as an Initiator

Conformal poly(cyclohexyl methacrylate) (pCHMA) thin films were synthesized via initiated chemical vapor deposition (iCVD), with tert-butyl peroxybenzoate (TBPOB) as the initiator, representing the first time that TBPOB has been used as an initiator for iCVD synthesis. Using TBPOB instead of tert-butyl peroxide (TBPO), the rate of iCVD film growth increased by a factor of up to seven at comparable conformality and lower the filament temperature from 257 to 170 °C at a comparable deposition rate of 3 nm/min. The conformal deposition of functional thin films is desired for applications including microfluidics, medical devices and membranes. Lower filament temperatures reduce the heat load to the deposition surface and thus are advantageous for polymeric substrates that are temperature sensitive or monomers that decompose at high temperatures. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results demonstrate the similarity of the TBPOB- to the TBPO-initiated pCHMA main chains. However, the aromatic group in TBPOB provided a unique spectral signature of the polymer chain end group in the FTIR and the peak intensity increased with increase of filament temperature. Scanning electron micrographs (SEMs) revealed that the pCHMA coatings are conformal over non-planar structures; however, at identical process conditions, TBPO-initiated films showed a slightly better conformality due to the lower sticking coefficient of TBPO. At a monomer partial pressure of 0.45, TBPOB has a sticking coefficient value of 0.1188 ± 0.0092, which is ∼3 times as high as that of TBPO (0.0413 ± 0.0058). The step coverage is insensitive to filament temperature if the surface concentration of the monomer is fixed.

Experimental and theoretical study of the role of the gas composition and plasma–surface interactions on the SnO x films stoichiometry prepared by DC magnetron reactive sputtering

In this paper, we have studied the tin oxide films deposition by DC magnetron reactive sputtering. We have investigated the discharge parameters such as discharge voltage and deposition rate and the discharge composition as a function of the input oxygen partial pressure. We have compared these results with the deposited films stoichiometry. In the constant current discharge mode, we observe, with increasing oxygen partial pressure, a decrease of the discharge voltage followed by a slight increase, and a drop of the deposition rate. For each experimental conditions, we measure the gas composition by mass spectrometry (glow discharge mass spectrometry mode and residual gas analysis mode (RGA)) and the deposited films stoichiometry by X-ray photoemission spectroscopy. The results are fitted by means of a model, taking into account the plasma–surface interactions. All the data are fitted by the same equation, with only four fitting parameters, namely the sticking-reaction coefficients of O and O 2 on Sn and SnO surfaces. Our results show that the main reaction is the reaction between the atomic oxygen and the metallic part (Sn) of the substrate. This reaction is characterized by a sticking coefficient value (α 1 0) of 0.96.

How the sorbent microgeometry effects the sorptional characteristics of cryopumps

To calculate and construct cryopumps used in large high-energy physics installations, in ITER particularly, it is necessary to know the value of pumping speed. Real surface of the sorbent is not flat. So a molecule of the pumped gas can be reflected from this surface several times. The real surface of different sorbents is analysed by a scanning tunnel microscope: activated coals Chemviron GFF/30, Chemviron SC II and non-evaporable getters. The real sticking coefficient value on the sorbent surface is calculated on the basis of integral trapping coefficient (pumping speed) of familiar experimental devices and of real geometric surface of the sorbent using the test particle Monte-Carlo method. Obtained results for various types of sorbents may be useful for engineers–constructors of cryosorption pumps.

Apparent and real values of common gas sticking coefficients on titanium films and application to getter pump devices with periodic active film renovation

The getter pump design needs reliable values of the sticking coefficient of the pumped gas as well as their change during the getter film saturation. The paper deals with averaging of known experimental data for sticking coefficients of common gases on titanium films, taking into account their roughness. The kinetics of N 2 and H 2 sticking coefficients at different pressures is also given, which makes possible the design of getter pump devices with periodic active film renovation.

Water droplet growth in a carbon dioxide atmosphere: A case for small sticking coefficient

Water droplet growth was measured in a CO2 atmosphere using an expansion cloud chamber. Sufficient pressure and temperature data were obtained in order to calculate droplet growth which was compared to the experimentally measured growth curves. As the droplets increased in size, it was found that the rate of change of the growth rate was not constant. The sticking coefficient in the droplet growth theory was treated as a parameter, but no single value of this coefficient would yield agreement between theory and experiment over the whole observational period. When the droplets are smaller than about 2.0 μ, a sticking coefficient value between 1.0 and 0.1 yields best agreement. For droplets of larger radius, it was found that an even smaller value of this coefficient, as small as 0.036, was required. The dehydration of the bicarbonate ion appears to be responsible for the lower value of the sticking coefficient.

Adsorption de l'éthyléne et de l'acétylène sur des films de rhénium evaporés sous ultra-vide; Hydrogénation de l'éthylène: II. Discussion des résultats expérimentaux et interprétation

A qualitative model is proposed in order to explain our experimental results on ethylene chemisorption on evaporated rhenium films and hydrogenation of ethylene (part I). The surface must present at least two kinds of surface sites (A and B). The second type (B), either preexists on the surface, or is induced by the adsorption phenomenon itself. On the most energetic ones (A), dissociation of ethylene and hydrogen is complete. Adsorption of ethylene is characterized by a sticking coefficient value of 0.1 if they are free and 1 if they are hydrogen covered. On sites B, ethylene is adsorbed without full dissociation (sticking coefficients equal to 0.015). independent on adsorption temperature. Hydrogen desorption is due to full dissociation of ethylene on the surface and a displacement reaction while ethane is produced by reaction between non-dissociated adsorbed ethylene and hydrogen in the gas phase. The same Rideal-Eley mechanism applies for hydrogenation of ethylene in quasi-stationary conditions, along with a self-poisoning mechanism involving dehydrogenation leading to C2H2 non-hydrogenable adsorbed species.

Interactions du rhénium à haute température avec N 2O sous basse pression

Starting at room temperature, N20 adsorption on rhenium proceeds dissociatively. Oxygen atoms remain on the surface while nitrogen molecules are desorbed. The overall process is characterized by an initial sticking coefficient value equal to 0.3 at 298 °K. In stationary conditions, and in a higher temperature range (> 1200°K) rhenium trioxide and oxygen atoms are the reaction products, depending on oxygen coverage on the surface. When the oxygen coverage is low, atomization, characterized by a reactive sticking probability of 0.2 is the only observable process. All the results are consistent with a model, previously proposed for the system oxygen-rhenium and oxygen-transition metals. The main differences in reaction rates between rhenium and oxygen or N 2O are interpreted in terms of saturation coverages.