SCD 500

High Vacuum Sputter Coater

The SCD500 High Vacuum Sputter Coater is designed for high vacuum coating for applications in electron microscopy and where small samples require metal coatings.

Key Features

• Compact bench unit
• Membrane and turbo molecular pump
• Programmable coating thickness
• Simple user friendly operation
• Suitable for all kind of different metal targets
• Suitable for high resolution FE-SEM coating

Detailed Description

The High Vacuum Sputtering Method

For very fine-grained sputter coated films Leica recommends high vacuum sputtering. Undesired residual gas components such as water vapour are virtually eliminated from the vacuum chamber by a high vacuum pump. The working pressure required for sputtering - approx. 10-2 mbar - is then re-established in the chamber with the admission of argon gas.

To start the sputtering process a high voltage is applied to the target (cathode). This produces a high voltage field between the target and the specimen table (anode). The free electrons in this field are forced into a spiral path by a magnet system where they collide with the argon atoms in the field. Each collision knocks out an electron of the outer shell of the argon atom, positively charging the otherwise neutral argon. This is a cascading process that causes a glow discharge (plasma) to ignite. The positively charged argon ions are now accelerated to the cathode (target) where they impinge, knocking off metal atoms as they hit the target. Collisions also occur between the metal atoms thus released and the other gas molecules in the vacuum chamber. This causes the metal atoms to scatter widely, forming a diffuse cloud.

The metal atoms from this cloud impinge on the specimen from all directions and condense evenly on it. Thus even very fissured specimen surfaces are coated with an even, thin metal film that is sufficiently electrically conductive for examination in the SEM. The fine grained structure of the sputtered film is a function of the target material, the working distance, the gas pressure and the sputtering current as well as of the process length.