6–6
Transpector CPM Operating Manual
6.3.1 Foreline Pump
The system controlled Foreline Pump configuration is selected when there is a
INFICON supplied Foreline Pump. If a customer supplied foreline pump is used to
back other vacuum equipment, a check valve can be used to temporarily isolate
the CPM from any short (<10 seconds) pressure bursts that would damage the
CPM. See Table 9-3 for the check valve part number.
A customer supplied pump must supply a continuous
foreline pressure between 10
-2
and 10 Torr.
6.3.1.1 Foreline Pirani Gauge
A Pirani gauge mounted to the CPM foreline block monitors the pressure in the
foreline. In the event of a pumping system malfunction, the foreline Pirani gauge
can be used to verify the foreline pressure is <10 Torr. For optimal pumping system
performance, the foreline pressure should be <2.25 Torr.
6.3.2 Turbo Molecular Pump
There are two types of pumping systems: Standard (non-corrosive) and corrosive.
The standard Turbo Molecular Pump is used in both applications.
The corrosive pump configuration is selected for applications such as CVD or Etch
or whenever corrosive gases are being sampled. The purge valve is automatically
opened when the CPM Turbo Molecular Pump is operating.
The corrosive service high vacuum pump requires 10 to 25 sccm of purge gas flow
through the bearing region to protect the bearings from corrosion and loss of
bearing lubricant by evaporation. The regulator is preset at the factory using a MFC
to produce 10 sccm of nitrogen purge. To produce 10 sccm, the nitrogen regulator
should be set between 10 and 15 psi (gauge).
For the corrosive service Turbo Molecular Pump
(CVD/Etch), nitrogen purge gas is required whenever the
system is operational.
WARNING - Risk Of Electric Shock
The Turbo Molecular Pump must be completely at rest
and the controller power supply must be disconnected
before removing the Turbo Molecular Pump connecting
cable.
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