Plasma Enhanced Chemical Vapor Deposition a Thin Film Technique for Organic and Inorganic Layers

Plasma enhanced chemical vapor deposition (PECVD) has a wide range of interest for thin films up to some lm thickness. It has widespread applications for high quality dielectric and semiconducting silicon alloys at deposition temperatures below 4508C and pressures at 1 mbar on plane substrates and attracts growing attention for the surface modification of polymers. The PECVD takes advantages of the possibility to alter the film properties in a wide range easily, and the coatings can achieve a variety of useful properties unobtainable by other coating techniques. An environmentally friendly plasma chemical reactor etch cleaning of SiOx, SiNx and other film materials can be applied by changing the process gas and without breaking the vacuum. PECVD can be used in a fixed substrate and continuous substrate flow mode. An capacitively coupled parallel-plate electrode assembly using radio-frequency (RF) excitation of the discharge is most widely used for substrate areas up to a few square meters. Among the capacitively excitation an inductively and electromagnetically excitation at frequencies in the RF and UHF range has also succeeded in achieving a high rate PECVD. Two applications are presented to show the characteristics and the potential of this technique, the PECVD of semiconducting hydrogenated amorphous silicon, intrinsic or doped, with low power densities using monosilane as a source gas for solar cells, thin films transistors and digital image sensors and the plasma polymerisation of organosilicon protection layers employing the HMDSO monomer and high power densities for mirrors and lenses.