Magnetron Sputtering (MS) uses a magnetron plasma for sputtering a metal layer on the substrates and oxidizing it to a stoichiometric metal-oxide in a microwave plasma afterwards. This technique allows to produce very dense and hard coatings.
In the coating machine a drum with a diameter of 120 cm holds the substrates. It rotates vertically in front of the two magnetrons and microwaves.
A plasma of ionized argon forms in front of the target. The positively charged argon ions are accelerated toward the negatively charged target, where they strike the face of the target and sputter metal atoms on the substrates.
Rotating into the microwave plasma the metal film is oxidized and ready for the next cycle.
The coatings are very hard and mechanically resistant and can work in nearly every environment. Specific coatings are space certified by ESA.
Two different material targets can be used in one configuration. The sputter rates are very stable, so the thickness control is done with high precision simply by time and with an optical monitor as backup. Especially for UV-coatings and cw-applications very high LIDT can be achieved.
As the process works with low temperatures coatings on plastic or other non-glasslike materials (e.g. fiber ends) are possible.
Like all sputter techniques, coatings made by MS may have high stress, depending on the wavelength region and coating materials used.
Pros and cons of MS
+ Very dense and hard
+ Space certified by ESA
+ High precision
+ High LIDT for UV-coatings
+ Low temperature coatings
– Compressive stress (case
Magnetron sputter coating machine