ABSTRACT
The roughness of the substrate must be much smaller than the film thickness; otherwise, a film might be interrupted somewhere. Second, silicon wafers are the standard material for the process machines from microelectronics. Every sputtering or lithography machines has holders for silicon wafers, while for other substrates we would have to construct extra equipment. The most simple method of PVD is evaporation. A metal is heated in high vacuum by electric current or by an electron beam (e-gun) until it melts and evaporates. The atoms sublimate onto a cooler substrate and generate a thin film. This type of PVD is usually used for laboratory experiments, exotic materials and sometimes for metallization. Doping intentionally introduces impurities into a semiconductor for the purpose of modulating its electrical properties. Doping can be performed during the wafer production for the whole wafer or during processing as local doping at the surface.
