Oxford Instruments OpAL, Системное руководство

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System Manual
As many of these by-products are toxic, it is a minimum requirement that these gases are exhausted in an
enclosed extraction system to the roof of the building - following health and safety regulations. In
addition to this, depending on local regulations, it may be necessary to have some form of gas scrubbing
before releasing these materials to the atmosphere.
Even if we were not running gases through the system, we would recommend that the system exhaust is
extracted correctly, since the pump exhaust will contain small droplets of pump oil which are in
themselves harmful to lung function.
Another important consideration is the gas absorbed in the pump oil. Since the exhaust gases contain HF
there will be a build up of HF in the pump oil. Therefore, it is important to use the correct protective
equipment when servicing the pump or changing pump oil, i.e. suitable gloves, protective clothing,
filtered facemask or breathing apparatus.
It is also worth remembering that when using O
2
processes the pump oil should be Fomblin oil and NOT
mineral oil to avoid risk of fire or explosive reaction between O
2
and mineral oil.
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Premature flaking of chamber wall liners / showerhead material can occur for a number of reasons:
1) Temperature cycling of showerhead / chamber walls can cause flaking, therefore it is important
that chamber walls are set to a stable temperature, e.g. 60C. It is also important that electrode
temperature is maintained at a constant value as this will also affect showerhead temperature.
2)
The system should NEVER be switched off overnight to save power. The system should be left
pumping with electrode maintained at deposition temperature and the chamber walls and
delivery lines maintained at temperature at all times to avoid flaking.
3) Incomplete cleaning during a previous clean cycle can lead to premature flaking.
4)
Wiping of chamber and or showerhead with water or IPA can leave residues which subsequently
causes early flake-off of films deposited.
5)
Wiping of chamber walls / showerhead with clean room wipes while they are hot can also leave
behind residues which cause premature flaking.
6) Repeated venting of chamber will cause flaking. This one of the main reasons it is recommended
to clean every 5-10 microns of film.
7) Mixed deposition of oxide, nitride, and oxynitride films can cause increased stresses in deposited
films and hence premature flaking.
8) Changes to standard recipes can also cause increased stress and hence premature flaking.
As part of the regular maintenance of the system the showerhead must be bead blasted. This is the only
Oxford Instruments Plasma Technology approved way of cleaning a showerhead. The use of solvents and
ultra-sonic baths is strongly discouraged. Scrubbing with Scotchbrite is also not recommended. OIPT will
not be able to support you if you use these alternative cleaning methods and still experience problems
the problems described in the above table with showerhead particles.
Recommended bead blasting specification:
Bead blast using alumina powder (aluminium oxide beads) of 180 grit size or less - maybe 120. Do not use
any solvents. Clean the showerhead after bead blasting using compressed air only. Hold the showerhead
up to the light to check that none of the holes are blocked by any grit from the bead blasting. Clean out
holes with paper clip or similar if blocked.
Process Information (Information contained in this document is confidential)
Issue 1: August 07 Page 8 of 14
Printed: 08 October 2007 11:00