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System Manual
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Most dry pumps have their own internal over-temperature switches. Loss of flow for these
pumps will eventually cause a temperature trip causing a process abort (process chamber
pump) and the relevant pump to be switched off. Devices such as turbo pumps have their
own internal protection against overheating and are not protected by external flow switches.
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Loss of process gas is detected when a mass flow controller goes out of tolerance during
process. The active process devices (normally plasma power) are paused, and gas flows remain
active. The process will resume automatically if gas is restored.
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An auxiliary circuit on the pump contactor detects pump failure due to overload or short
circuit, and the process gases are immediately halted.
If a rotary vane or dry vacuum pump stops pumping for other reasons during a process, e.g. if
it fails or its power is disconnected, and the vacuum interlock switch’s contacts remain closed,
process gas will continue to flow into the process chamber. Gas flow will stop when the
chamber pressure exceeds the vacuum switch trip level of 600 mbar absolute. The front-end
software will show the interlock status as ‘fault’.
WARNING
DISCONNECTING THE POWER TO AUXILIARY EQUIPMENT, ESPECIALLY VACUUM PUMPS, WHILE
RUNNING A PROCESS CAN CAUSE A HAZARD IN THE PROCESS CHAMBER.
ENSURE THAT THE SYSTEM IS SHUT DOWN USING THE PROCEDURE GIVEN IN SUB-SECTION 5.4.5
BEFORE DISCONNECTING ANY POWER CABLES FROM THE POWER BOX, OR SWITCHING OFF ANY
ELECTRICAL SUPPLIES TO AUXILIARY EQUIPMENT.
WARNING
IF THE EQUIPMENT HALTS DURING PROCESS BECAUSE THE VACUUM SWITCH HAS OPENED, THERE
MAY BE A SERIOUS GAS HAZARD IN THE CHAMBER AND PUMPING LINES.
ASSESS THE RISKS BEFORE TRYING TO PUMP OR VENT THE CHAMBER.
PERSONAL PROTECTIVE EQUIPMENT MAY BE NECESSARY.
Operating Instructions
Printed: 06 November 2007 09:42
Page 5-9 of 60
Generic (OpAL Plasma) Issue 1: Oct. 07
Summary of Contents for OpAL
Page 14: ......