Photography by Gabiele Photography
Sputtering
This a very popular thin film deposition technique. It is used in
optical and electronical applications. The substrate, and the material
to be growth are located in a vacuum chamber, one facing the other. An
inert gas is introduced and ionized, then collides with the material,
also called target. The target is eroded by inert gas ions, the materila
is sputtered onto the substrate: A thin film is formed. During this
process a plasma is created. Our laboratory developed a nobel technique
to monitor the target poissoning, and study stequiometric composition of
the film, using optical emission spectroscopy of the plasma.
There are some variation to the described procedure. The use of two or
more targets, with different materials. Introduction of a reactive gas
to the chamber, ussually Oxigen or Nitrogen. Mantain the reactive gas
constant during deposition or varying the flux to produce a continuous
variation of the physical properties of the thilm.
Our main application of thin films is to optical interference filters.
For this purpose a multilayer is coated on the substrate in such a way
to modify the its optical performance: Improve o reduce reflectance,
select a narrow band transmittance, minimize the heat emission, etc.
Also taking advantage of magnetron technology ensures thickness
uniformity and higher quality for the thin film's coats. Using this
method it is possible to work with materials with very high melting
points. Sputter deposited films have a composition close to that of the
bulk material.