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In order to make the most effective use of your thin film deposition system, it is necessary to understand some of the basic parameters involved in creating thin films. The deposition process can be broadly classified into physical vapor deposition ( PVD ) and chemical vapor deposition ( CVD ). In CVD , the film growth occurs at higher temperatures leading to the development of corrosive gaseous products and might leave impurities on the film. The PVD process can be performed at lower deposition temperatures also leaving corrosive products aside, but deposition rates are lower and it leaves residual compressive stress in the film. Electron beam physical vapor deposition, nevertheless, yields a high deposition rate from 0.1 μm / min to 10 μm / min at relatively low substrate temperatures, with very high material usage efficiency. Due to the very high deposition rate, this process has industrial applications for wear resistant and thermal barrier coatings in aerospace industries, hard coatings for cutting and tool industries, and electronic and optical films for semiconductor industries. In principle, solid evaporant such as powder, granules, lumps, or shaped plug, is placed in the source's copper hearth or in a hearth-liner. A high electron flux produced by hot filament positioned beneath the source is extracted and electro statically and magnetically bent/focused on the top of the evaporant. The electron beam's energy elevates the evaporant's surface temperature. Seldom is the beam rastered to increase the evaporation region. Since the evaporation region is enclosed by cooler (often solid) evaporant, unlike other thermal sources, the e-beam source's vapor plume is chiefly uncontaminated by crucible material. Production scale e-beam sources are usually single pocket (one hearth). Multipocket source (4 or 6 hearths) is available for R & D applications. A cover plate obscures the pockets "not-in-use" to prevent vapor cross talk. Multipocket sources are particularly convenient when depositing multilayer films on a single substrate.