Thin film deposition techniques/processing plasma-enhanced chemical vapor

CVD is a well-understood thin film deposition method that uses chemical reactions of vapor-phase precursors. CVD processes have traditionally been initiated and controlled by heat as the source of energy. An elevated deposition temperature is normally required, which restricts the types of substrates that can be used and coating materials that can be deposited, especially thermally sensitive ones (Jones and Hitchman, 2009). However, thermal energy is not the only energy supplied to the system plasmas and photons are widely used in CVD processes. Plasma-enhanced chemical vapor deposition (PECVD), or plasma-assisted CVD, is a CVD technique in which plasma in lieu of thermal energy is used primarily to activate ions and radicals in the chemical reactions leading to layer formation on the substrate. One major advantage of PECVD over... 

The second method is chemical vapor deposition (CVD). As suggested by the name, unlike PVD, chemical reactions are involved in CVD. Precursor materials in gas phases are introduced into heated furnaces and react at the substrate surface to deposit the desired thin film. For example, CVD is typically performed in low pressure conditions (< 1 Torr) this technique is called LPCVD and usually requires an inert diluent gas such as nitrogen. CVD processes typically involve high temperatures (above 500°C). This is a very important factor to consider in a designing a fabrication process. For example, no metal except tungsten (W) is allowed into CVD furnaces. LPCVD usually has very slow deposition rate. Plasma-enhanced CVD (PECVD) can deposit dielectric films much faster. It also allows deposition at lower temperatures (<400°C). This is very useful when a substrate has already been metalized. 

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