Physical vapor deposition application methods

Recently, many methods in the synthesis of c-BN films were studied, which include physical vapor deposition [1,5-7] (PVD) and chemical vapor deposition [1,8,9] (CVD, such as PECVD, HFCVD, MW-ECR-CVD). Most experiments have indicated that the commercial application of c-BN films depends on enhancement and improvement in the stability and repeatability of preparation process. Generally, ion energy flow density or ion bombardment was attributed to the essential factor with the influence in the c-BN formation [1,10-13]. However, it is noted that the discrepancy between PVD and CVD maybe result from the difference in the substrate temperature (Ts , ). Unfortunately, the role which Tjub plays on the growth of cubic phase in PVD was seldom investigated systemically. 

For their rich potential in various applications described in the previous section, the synthesis and assembly of various ZnO micro and nanostructures have been extensively explored using both gas-phase and solution-based approaches. The most commonly used gas-phase growth approaches for synthesizing ZnO structures at the nanometer and micrometer scale include physical vapor deposition (40, 41), pulsed laser deposition (42), chemical vapor deposition (43), metal-organic chemical vapor deposition (44), vapor-liquid-solid epitaxial mechanisms (24, 28, 29, 45), and epitaxial electrodeposition (46). In solution-based synthesis approaches, growth methods such as hydrothermal decomposition processes (47, 48) and homogeneous precipitation of ZnO in aqueous solutions (49-51) were pursued. 

Coating and thin films can be applied by a number of methods. In thermal or plasma spraying, a ceramic feedstock, either a powder or a rod, is fed to a gun from which it is sprayed onto a substrate. For the process of physical vapor deposition (PVD), which is conducted inside an enclosed chamber, a condensed phase is introduced into the gas phase by either evaporation or by sputtering. It then deposits by condensation or reaction onto a substrate. A plasma environment is sometimes used in conjunction with PVD to accelerate the deposition process or to improve the properties of the film. For coatings or films made by chemical vapor deposition (CVD), gas phase chemicals in an appropriate ratio inside a chamber are exposed to a solid surface at high temperature when the gaseous species strike the hot surface, they react to form the desired ceramic material. CVD-type reactions are also used to infiltrate porous substrates [chemical vapor infiltration (CVI)]. For some applications, the CVD reactions take place in a plasma environment to improve the deposition rate or the film properties. 

For industrial application usually such metals as palladium, platinum, iron, ruthenium, cobalt, molybdemun, nickel, either alone or as bimetallic catalyst are used. They are introduced using ion exchange, excess solution impregnation, incipient-wetness impregnation or physical vapor deposition methods. 

Another application is uniform deposition of a thin him of ceramic materials onto a substrate. Thin him formation is achieved by electrospraying a ceramic solution. This method is more economical than chemical/physical vapor deposition methods. Figure 22.16b shows the SEM of SiC ceramic thin him deposited on a substrate. " ... 

At an industrial applications, the TBC coverings can be produced by thermal spraying method in the air plasma spray (APS) atmosphere, at lowered pressure low pressure plasma spray (EPPS) from APS or by the electron beam physical vapor deposition method (EB-PVD), these are all dry-route processes. By these processes, coatings have different microstructures lamellar microstructure consisting... 

This work reports the development of a polymeric/sol-gel route for the deposition of silicon carbide and silicon oxycarbide thin films for applications such as heat-, corrosion-, and wear-resistant coatings, coatings on fibers for controlling the interaction with the matrix in ceramic matrix composites, or films in electronic and optoelectronic devices. This method, in which the pre-ceramic films are converted to a ceramic coating either by a conventional high temperature annealing or by ion irradiation, is alternative to conventional methods such as chemical or physical vapor deposition (CVD, PVD), molecular beam epitaxy, sputtering, plasma spray, or laser ablation, which are not always practical or cost efficient. 

Today SiC thin films (< 1 pm thickness) can also be produced by physical vapor deposition (PVD), for example by sputtering, which method allows lower substrate temperatures, but works more slowly. Electrically conductive B/N-doped sintered aSiC with up to 9weight-% free carbon has been developed as target material, [133]. Novel applications for PVDSiC include films for computer storage media, protective coating for lenses, and microwaveable packaging for food. 

Most other metal films are deposited by physical vapor deposition, usually evaporation or sputtering. Both processes require a high vacuum and are relatively expensive. Sputtering is the most expensive method, but it allows a much better control of the film composition. As a result of mechanization of physical vapor deposition, the deposition price of metal films is now so low that application for general purpose resistors is possible. 

Seshan, K. 2002. Handbook of Thin-Film Deposition Processes and Techniques Principles, Methods, Equipment and Applications, 2nd ed. Norwich, NY Noyes Publications. Brings together information on physical vapor deposition techniques. Available online on Knovel. 

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