Reactive plasma

Rutscher A and Wagner H - E 1993 Chemical quasi-equilibria a new concept in the description of reactive plasmas Plasma Sources Sc/. Technol 2 279-88... 

Experimentally, there has been but little direct observation of the reactive intermediates present in this, or any other, t5rpe of discharge, as it is extraordinarily difficult to analyze a reactive plasma without perturbing the system. 

A. Ricard, Reactive Plasmas. Societe Fran aise du Vide, Paris, 1996. 

The quality of the thin film depends on preferential interactions between precursor and coating substrate. However, the initial layer is clearly the most important and, in the case of nanocarbons, the surface chemistry must be tailored. For most ALD precursors, hydrophilic surface groups enhance deposition, which can be achieved by functionalizing the nanocarbon prior to placement in the ALD reaction chamber or by treating the sample within the chamber with reactive plasma. Among the many in situ hybridization techniques, ALD provides best control of thin film thickness. 

Fig. 8.1.2 Schematic model of nitriding zone of iron vapor and/or condensed iron particles in reactive plasma-metal reaction. (From Ref. 17, p. 412. with kind permission from The Japan Institute of Metals.)...

The effect of reactive plasma and its distance form the PE film surface has also been studied in detail [138]. The surface of polyethylene films was modified with various water-soluble polymers [(poly[2-(methacryloy-loxy)ethyl phosphorylcholine] (PMPC), poly[2-(glucosyloxy)ethyl methacrylate] (PGEMA), poly(N-isopropylacrylamide) (PNIPAAm) and poly[N-(2-hy-droxypropyl) methacrylamide] (PHPMA)] using Ar plasma-post polymerisation technique [139]. Here, the reactive sites were generated on the PE surface under the influence of argon plasma. These reactive sites on the surface were then utilised to covalently anchor the functional monomers as shown in Scheme 11. 

Electric arc processes have been given a new lease on fife in the guise of plasma reactors, especially those involving cold, or nonthermal plasmas, with electron temperatures of I (E-IO5 K and gas temperatures of 102-103 K. Plasmas of this kind can be used to activate and functionalize inert molecules, but usually with only poor selectivities and low energy yields ( 0.01 mol/kWh ). The use of catalytic additives may offer some potential for improvement, but reactive plasma processes will probably remain restricted to a few specific applications. 

B15. Beschomer, R., Horny, H. P., Petruch, U. R., and Kaiserling, E., Frequent expression of haemopoietic and non-haemopoietic antigens by reactive plasma cells An immunohistochemical study using formalin-fixed, paraffin-embedded tissue. Histol. Histopathol. 14, 805-812 (1999). 

The question of surface chemical reactivity is critically dependent on the chemical nature and composition of the wall and the chemical nature and energies of the particles arriving at the wall. It will be necessary to develop experimental techniques to monitor the changing chemical composition of the first wall resulting from the flux of catalytic reactive plasma particles. Since the presence of active forms of hydrogen is inherent in all fusion devices, the potential for problems associated with surface chemical reactions of these species will always be present, only the form and magnitude of the problem will change. 

Magnetic field control of reactive plasma etching. Appl. Phys. Lett. 35 393 (1979). 

The polymerization of p-xylylenes on condensation is extremely rapid and appears to proceed from gaseous monomer to solid polymer without passing through a viscous stage. The monomer behaves as a reactive plasma which surrounds solid objects placed in the deposition chamber. 

Modes, T., Scheffel, B., Metzner, C., Zywitzki, O. and Reinhold, E. (2005). Structure and properties of titanium oxide layers deposited by reactive plasma activated electron beam evaporation. Surf. Coat. Technol. 200(1 4), 306-309. 

This expression is unusable as it is, but it reduces to some interesting limits for some practical cases. Generally direct sputtering processes are negligible in reactive plasmas with respect to chemical processes, so one can omit the term K, Y, n and then ... 

K. Akashi, Preparation of Superconducting Y-Ba-Cu-0 Films by a Reactive Plasma Evaporation Method, Applied Physics Letters, Vol.52, 1988, pp. 1274-1276. 

As far as plasma polymerization and plasma treatment of materials, particularly organic polymers, are concerned, the luminous gas phase (low-pressure plasma) can be divided into three major groups based on the mode of consumption of the gas used to create the plasma (1) chemically nonreactive plasma (2) chemically reactive plasma and (3) polymer-forming plasma. The terms chemically reactive and chemically nonreactive are based strictly on whether the gas used in glow discharge is consumed in chemical processes yielding products in the gas phase or being incorporated into the solid phase by chemical bonds. 

These environments include high temperatures, exceedingly corrosive etching chemicals such as strong acids, and reactive plasmas. 

The metal-RIE process is used in the fabrication of Al interconnects on chips. In this process, a blanket thin film of Al (or Al alloys, like Al—Cu, Al—Si) is deposited and then etched in a reactive plasma (RIE) through a photoresist stencil. After RIE, a... 

Plasma deposition has also been utilized to deposit PEO-like materials from volatile precursors onto a variety of subjects. This technique involves generating a reactive plasma containing PEO-like monomers, which polymerize and deposit, often with chemical grafting, onto any surface within the plasma. The availability of large-scale vacuum apparatus makes this technique feasible on an industrial scale. The materials deposited by this technique were often shown to contain only short PEO segments yet greatly reduced protein deposition was observed and the small amounts (ng/cm) that did deposit were easily eluted. ... 

Careful preparation of the deposition surface is an important step in the study of surface interactions with chemically reactive species from the gas plasma phase. Two types of silicon surfaces are of particular interest crystalline and amorphous surfaces that are exposed to the chemically reactive plasma species during the PECVD process. Crystalline surfaces, especially the Si(OOl) surface, are representative of commonly used crystalhne substrates (Si wafers) in various experimental studies and practical applications. Amorphous surfaces are representative growth surfaces at later stages of the PECVD process, after an a-Si H him has been deposited on the substrate. 

Coburn, J. W., and M. Chen. Optical emission spectroscopy of reactive plasmas A method for correlating emission intensities to reactive... 

In addition to electrochemical polymerization, reactive monomers can be polymerized onto surfaces by using radio frequency (rf) plasma polymerization [194-197]. In this technique an electric discharge through the vapor forms a reactive plasma that chemically modifies the surface. Examples of applications of rf plasma-polymerized surfaces include the formation of (C2F4) films on fiber optic sensors for detection of volatile organics [198] and the formation of alkylamine surfaces on glass fibers by plasma treatment for subsequent chemical modification [199]. 

In addition to the chemical etching method described above, other etching methods such as chemical anisotropic etching, and reactive plasma etching, may also be used to define the geometric configuration of the sensor element. These etching techniques are also established microelectronic processes and are extensively described elsewhere [6]. 

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