Surface kinetics, plasma processes

Atomic force microscopy has been up to now only scarcely used by the plasma processing community. Results mainly concern low-resolution measurements, that is modification of the surface roughness induced by the plasma [43,44], Micro masking effects have been observed when processing Si with a SF6 plasma beam at low temperature (Fig. 11) and correlated to the multi-layer adsorption of plasma species as observed by XPS [45], Further development of vacuum techniques should allow high resolution surface probe microscopy measurements on plasma-treated samples, and possibly lead to complementary information on adsorption kinetics, surface density of states. 

Theoretically, if reactions are able to proceed through either a Rideal-Eley step or a Langmuir-Hinshelwood step, the Langmuir-Hinshelwood route is much more preferred due to the extremely short time scale (picosecond) of a gas-surface collision. The kinetics of a Rideal-Eley step, however, can become important at extreme conditions. For example, the reactions involved during plasma processing of electronic materials... 

The results indicate that the initial rate of transport of PE is rapid and proceeds without a lag (Fig. 8). The transport process is insensitive to metabolic poisons that disrupt vesicle transport and cytoskeletal structure. The rapid transport kinetics occur at rates consistent with a soluble carrier-mediated process or transfer at zones of apposition between membranes. Analysis of the kinetics of the process is complicated since only PE at the outer leaflet of the plasma membrane is measured, and the basal scramblase activity or the leakage of the ATP-dependent aminophospholipid transporter activity within the plasma membrane may be a step required for the lipid to arrive at this location. Despite these complications, the results clearly indicate that the initial rate of arrival of PE at the plasma membrane occurs on a timescale that clearly distinguishes it from well-characterized vesicle transport phenomena, and is independent of processes involved in protein transport to the cell surface. 

Etching Anisotropy Analysis in the Framework of Surface Kinetics of Plasma Etching. Based on relation (8-22), analyze the substrate temperature effect on etching anisotropy. Which step of the ion energy-driven etching is most affected by substrate temperature Compare effects of translational gas temperature and electron temperature on the plasma etching process. 

Magnetospheric plasmas are produced and heavily influenced by solar emissions and activity and by magnetic fields of the planets. Interplanetary plasmas result from solar emission processes alone. Protons in the solar wind have low densities (10—100/cm ) and temperatures below 10 to more than 10 K (1—10 eV). Their average outward kinetic energy from the sun is approximately 400 eV (58,59). The various 2ones and phenomena from the sun s visible surface to the upper atmosphere of the earth have been discussed (60—62). 

Various plasma diagnostic techniques have been used to study the SiH discharges and results have helped in the understanding of the growth kinetics. These processes can be categorized as r-f discharge electron kinetics, plasma chemistry including transport, and surface deposition kinetics. 

The rates of these reactions bodr in the gas phase and on the condensed phase are usually increased as the temperature of die process is increased, but a substantially greater effect on the rate cati often be achieved when the reactants are adsorbed on die surface of a solid, or if intense beams of radiation of suitable wavelength and particles, such as electrons and gaseous ions with sufficient kinetic energies, can be used to bring about molecular decomposition. It follows drat the development of lasers and plasmas has considerably increased die scope and utility of drese thermochemical processes. These topics will be considered in the later chapters. 

The implied capability of these plasma deposits to inhibit corrosion at metal surfaces may be of practical as well as of basic importance. An important consideration in this respect is the rapid rate of deposition for such protective coatings attainable at micro-wave frequencies. Since plasma technology is still in a process of evolution, optimum deposition kinetics cannot yet be stated however, the marked effect of excitation frequency on the deposition of organo-silicones can be documented (10), as in Fig. 3. Here, using terminology and comparative data due to Yasuda et al. (2). it is shown that deposition rates in microwave plasmas exceed those at lower (e.g. radio) frequencies by about an order of magnitude. 

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