OpAL Oxford Instruments Plasma Technology System Manual
WARNING
BEFORE PROCEEDING WITH ANY MAINTENANCE WORK, READ SECTION 1 - HEALTH AND SAFETY.
2) The O-rings should be checked monthly but replaced as and when necessary.
Replacement
O-rings should be constructed of FR10/80 and pre-baked to 180°C to
minimise the risk of gas escaping from the chamber. The chamber lid O-ring should not
need to be removed unless it leaks. Clean the O-ring
in situ
using a lint-free cloth wetted
with Isopropyl Alcohol.
To change the lid O-ring (use gloves):
i) Remove the O-ring, being careful not to damage the retaining groove.
ii) Use a lint-free cloth and IPA to clean the O-ring sealing face on the
chamber.
iii) The new O-ring, cleaned with IPA, should be inserted with no twists.
Stretch the O-ring evenly as it is inserted to avoid local regions of
stretching.
3) Monitor the vacuum integrity of the system by pumping thoroughly, isolating the
process chamber and noting the rate of pressure rise. An abnormally high value
may indicate a leak or heavy contamination of the process chamber. See sub-
section 6.2.2.1 for leak check procedures.
4) Mo
nitor the rotary pump condition by timing how long it takes to pump from
atmosphere to 0.1 Torr. An increase in time may indicate deteriorating pump
performance.
5) Monitor the condition of the oil filter by ensuring that the oil is still flowing.
Ensure that the oil filter is not clogged by ensuring that the pressure gauge
reading is < 2 bar
6) Check the zero setting of the capacitance manometer. A rotary pump should give
a base pressure below 10 mTorr, so a true zero pressure cannot be set in this
case. Either the gauge should be set to the same arbitrary reference level (e.g.
10 mTorr), or it should be set to zero on another vacuum system with a known
base pressure, and carefully re-installed in the OpAL system.
7) Monitor the performance of each mass flow controller, by noting the system
pressure with 10%, 50% and 100% flow set points and the throttle fully open. A
change may indicate a deterioration in MFC performance, or a change in
pumping speed.
6.2.2.1 Vacuum leak rate check
To perform a process chamber leak-rate check, use the following procedure:
1) Pump the system down using a manual process.
2) Press the Abort button. The gate valve will close and the sealed chamber
pressure can be monitored on-screen.
3) To perform a process chamber and gas line leak-rate check, use the following
procedure:
Maintenance
Issue 4: July 10 Page 6-4 of 16 Printed: 14-Jul-10, 8:14
To Next Page
