EQUIPMENT & ACCESSORIES CATALOG EDITION V
Terms and Techniques Magnetron Sputtering
LARGE CHAMBER SPUTTER COATERS zzzQ300T ES Plus (continued)
Magnetron sputtering using a crossed-field electromagnetic configuration keeps the ejected secondary electrons near the cathode (target) surface and in a closed path on the surface. This allows a dense plasma to be established near the sputter target surface. The ions that are accelerated from the plasma do not sustain energy loss by collision before they bombard the sputter target.
For electron microscopy (EM) specimen coating, the magnetron sputtering head design ensures that minimal heat energy (electrons) reach the specimen surface. This is important as it reduces heat damage to specimen and is a significant factor in ensuring the grain size within the sputtered film is optimally small essential for high resolution field emission scanning electron microscopy (FE-SEM).
Film Thickness Monitor (FTM)
A film thickness monitor can be used to monitor and control the thickness of sputtered and evaporated metal films. A gold-coated quartz crystal is mounted in the vacuum chamber of the coating system, ideally close to the specimen or substrate. The quartz crystal is made to oscillate at a defined frequency, using an externally-mounted oscillator. As metal is deposited on the quartz crystal, the frequency of oscillation alters and the change is converted to a digital (eg LED) display on the monitoring unit.
Film thickness monitors are available for use with most of our coating systems and cryo preparation systems.
Turbomolecular Pump
A turbomolecular (turbo) pump is a type of vacuum pump used to obtain and maintain high vacuum. The principle of operation is that gas molecules within a vacuum chamber can be given momentum in a desired direction by repeated collisions with a rapidly spinning turbine rotor. The rotor hits gas molecules from the inlet of the pump towards the exhaust in order to create or maintain a vacuum. A turbo pump normally works in tandem with a low-vacuum pump, such as a rotary vacuum pump, which is used to rough pump the vacuum system (eg sputter coater or vacuum evaporator) during initial pump-down period, and to back the turbo pump (ie remove gases from the back of the pump) during high-vacuum operation.
Iridium Sputter Coating
Sputtering with iridium (Ir) is increasingly popular for high resolution sputter coating of field emission scanning electron microscopy (FE-SEM) specimens, because iridium will produce films with very small grain structure and it is a non-oxidising metal. It is increasingly preferred to chromium (Cr) as a coating material for FE-SEM. Iridium-coated specimens can be stored at atmospheric pressure, compared to chromium - which readily oxidises on contact with air.
Pure silk coated 10nm Au x 18k magnification
Ladybird larvae hair coated 10nm Au x 2.5k magnification
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