Chemical vapour deposition

Chemical vapour deposition is the process in which a film is deposited by a chemical reaction or decomposition of a gas mixture at elevated temperature at the wafer surface or in its vicinity. Typical examples of CVD films are single crystal silicon, polycrystalline silicon, silicon-dioxide, silicon nitride, composite dielectrics, compound semiconductors, metals and metal compounds. Physical vapour deposition

Vacuum evaporation occurs when a source material (e.g. aluminium) is heated above its melting point in an evacuated chamber. The evaporated atoms then travel at high velocity in straight line trajectories and get deposited onto the wafers which are placed normal to the trajectories. The source can be made molten by resistance heating, RF heating or with a focussed electron beam (electron gun).