The ability to deposit films on a semiconductor wafers is an essential building block of IC fabrication. A variety of processing methods are in use today and the most important among them can be divided between PVD and CVD. PVD refers to a variety of deposition processes which are performed in a vacuum environment. No chemical reaction occurs at the deposition site, but rather a material is released from a source and transferred to the substrate. The most commonly used PVD processes are evaporation and sputtering. CVD, on the other hand, relies on a chemical reaction at the deposition site in order for a new material to be generated. A high deposition temperature is usually required in order to drive the reaction and the resulting thin film has a very good step coverage and better uniformity when compared to PVD.