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#1144
Author: Charles A. Bishop, C.A.Bishop Consulting Ltd.
Email: cabuk1@freenetname.co.uk
Subject: There are a range of sputtering processes from D.C. diode sputtering, R.F. sputtering, magnetron sputtering, ion beam sputtering.
There are a range of sputtering processes from D.C. diode sputtering, R.F. Sputtering, magnetron sputtering, ion beam sputtering.
Basically you are aiming to bombard a surface with atoms with sufficient energy such that some of the target material is ejected from the surface. These ejected atoms are condensed on a suitably placed substrate thus building up a coating.
To improve the efficiency of the process it is usually done under a moderate vacuum. Also to aid efficiency it is common for the sputtering source to have some magnetic confinement thus making a magnetron source. The effect of the magnetic field is to spiral the electrons so that they have more chance of undergoing an ionising collision thus enabling the plasma to be operated at a higher density. The target is run as the cathode in the process and so the heavier ions are accelerated into the target material ejecting atoms.
An example of a simple inefficient sputtering source is a fluorescent lamp. Over a period of time you will see a dark ring appear around one end of the tube, this is sputtered material from the cathode. The light output from the tube is from the sputtering plasma bombarding the glass tube that is coated with a fluorescent material that converts the pinkish plasma to a white light that provides the illumination we are familiar with.
A good reference book on sputtering is 'Thin Film Processes' Ed by John L. Vossen & Werner Kern Published by Academic Press ISBN NO 0-12-728250-5
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