Description
OM-SC7610
SC7610 Sputter Coater
16
Issue 1
4.4.1
Operational Description
The SC7610 operates at a fixed potential of 800 Volts dc.
An HV voltage is applied between the Target (cathode ) and Baseplate (anode) which is at earth
potential. A pressure interlock ensures that the HV supply cannot be activated until vacuum
chamber pressure is reduced to 10
-1
mbar or better. Low pressure gas (argon) is leaked into the
vacuum chamber to provide a medium for ionisation. Figure 2.2 shows the principles of operation of
the SC7610.
Electrons emitted by the cathode, concentrated in the vicinity of the target by the magnetic field,
collide with the gas molecules, producing positive ions (due to secondary electron emission).
Positive ions attracted by the negative potential of the cathode, bombard the target, causing erosion
of the target material. The dislodged target atoms falling toward the sample follow multiple paths
due to collisions with the ionized gas, coating the sample on all exposed faces.
A gas discharge glow centered about the cathode is visible.
Figure 4.2 Sputter Coater Operation
4.4.2
Pumping Requirements
The work chamber has to be evacuated to 10
-3
mbar which can be achieved in a reasonable time
(depending on the cleanliness of the chamber) using a 90 l/m two stage rotary pump preferably
incorporating an anti-suck back device and fitted with an oil mist filter on the exhaust.
4.5
Interlocks
Safety interlocks are incorporated in the SC7610 Sputter Coater to prevent power being switched
on with the chamber top plate not in the closed position. Also to cut power to the instrument if
vacuum pressure is lost.
WARNING
HAZARD TO HEALTH!
Potentially lethal voltages are used in this equipment.
Under no circumstances should interlock connections be over-ridden.