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3. Sputter Coating

Table of Contents:

1. Introduction
2. Gaseous Conduction
3. Glow Discharge
4. Sputter Coating
5. Operating Characteristics
6. Specification

It has been indicated that under conditions of glow discharge, ion bombardment of the cathode will occur, this results in the erosion of the cathode material and is termed plasma sputtering, the subsequent omni-directional deposition of the sputtered atoms forming coatings of the original cathode material.

This process is enhanced in Sputter Coaters for use in Scanning Electron Microscopy where one objective is to provide an electrically conductive thin film representative of the surface topography of the specimen to be viewed, such films inhibit 'charging', reduce thermal damage, and enhance secondary electron emission.

The most common arrangement for a D.C. (Direct Current) Sputter Coater is to make the negative cathode the target material to be sputtered (typically Gold), and to locate the specimens to be coated on the anode (which is usually 'earthed' to the system and the specimens are effectively at 'ground' potential). The desired operating pressure (relative vacuum) is obtained by using a suitable applied vacuum, usually a two stage rotary pump. An inert gas, such as argon, is admitted to the chamber by a fine control valve.

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