The following table of common sputtering target materials is useful in making comparisons between thin film deposition processes. The second column shows the maximum theoretical Density of each PVD coating material. While this density has no bearing on sputtering rate, higher density targets (as close as possible to the theoretical maximum) last longer and have fewer voids or inclusions, so they provide better films.
The sputtering "Yield" data in the third column represents the number of target atoms sputtered (ejected from the target) per argon ion striking the target with a kinetic energy of 600 ev. This energy is typical for an argon plasma. Magnetron design factors such as the magnetic field strength (and process parameters such as gas composition and pressure) will affect these data, of course. But they remain useful for comparison purposes.
The "Rate" data are representative of the film deposition rate at maximum power density (i.e. about 250 w/in2, with direct cooling) and a 4" source to substrate distance. The rates will decrease linearly with lower power levels. With all other factors unchanged, the film deposition rate will:
- Decrease by approximately 25% per inch beyond the 4" source to substrate distance.
- Increase by approximately 35% per inch closer than the 4" substrate distance.
Yield @ 600 ev
* The above sputtering yield rates are provided as a comparison. Specific thin film deposition rates will vary based upon PVD coating system design and process parameters.
Thin Film Deposition is a vacuum technology for applying coatings of pure materials to the surface of various objects. The coatings, also called films, are usually in the thickness range of angstroms to microns and can be a single material, or can be multiple materials in a layered structure. This paper discusses the basic principles of thickness and rate control by use of quartz crystal monitoring... Read More