Plasma Enhanced Chemical Vapor Deposition
(PECVD)
Chemical Vapor Deposition (CVD)
A thin film material is formed on a substrate by thermal decomposition and/or reaction of gaseous compounds. The material is deposited in the gas phase onto the substrate surface.
Sputtering
Material is deposited by bombarding a target with energetic ions, typically Ar+. Atoms on the surface of the target are knocked loose and delivered to the substrate, resulting in deposition. Electrically conductive materials can be deposited by a dc power source in which the target acts as a cathode and the substrate(s) are mounted on a system anode, thus directing the deposited material from target to substrate . Deposition of dielectric materials requires an RF power source to deliver energy to the argon atoms. Sputtering can also be used to etch a material as a method of cleaning the substrate prior to film deposition; sputtering can be used to clean contact windows prior to metal deposition. The etching process by sputtering can be thought of as a reversal of the sputter deposition process. With this method, almost any material can be deposited and the control is good, but the deposition rates are rather low.
Electron-Beam Evaporation (e-beam)
A high-intensity beam of electrons is focused on a source target containing the material to be evaporated, with an energy up to 15KeV. The energy from the electron beam leaving a filament, bent by a magnetic field, melts a region of the target, resulting in material being evaporated from the source and covers the substrate with a thin layer. This method requires a low vacuum due to the need for long filament lifetime. The vacuum is normally in the range of 10-6 Torr. Because the evaporation rates are very high, the cycle time is short, and the arriving atoms contain low contamination, leading to a better quality film. The e-beam is not as optimal as sputtering or CVD in regard to proper control of film structure because of the higher rates of deposition. However, to some extent the deposition can be lowered by running the process at low power.
Thermal Evaporator
