6–2
Transpector CPM Operating Manual
6.1.1 HexBlock Inlet
V1—Low pressure sampling (LP). Indicates background pressures for some
etch or CVD process. (No bypass available.)
V2—High pressure sampling (HP). Indicates process pressures for etch, CVD
and 300 mm degas sampling. Bypass is optional.
V3—High Conductance. Similar to a wide open position. Used for any high
vacuum condition lower than 1 mTorr.
V4—Bypass. Used in conjunction with V2 in high pressure applications (above
1 Torr). V4 connects to the interstage of the Turbo Molecular Pump via a bypass
tube which pulls gas from the process directly to V2. This can cut the response
time down from several minutes to less than ten seconds for a 100 Torr process.
The V4 bypass inlet typically consumes approximately 17 sccms of process gas.
NOTE: When sampling lighter gases such as hydrogen and helium, it may be
necessary to connect the V4 bypass tube to the foreline pump port rather
than the turbo pump interstage port to improve pumping efficiency.
To prevent pressure bursts to the RGA, V4 should open
before V2 to ensure the pressure is correct for the V2
orifice. When V2 is closed, V4 should remain open for
several seconds to pump out residuals left from sampling
the process.
V5—Calibration Reference. Used for mass tuning and as a sensitivity
reference, providing:
a means to tune the RGA
a reference for adjusting the EM voltage
a way to check whether the orifices are getting dirty or clogged
a reference for tracking the performance of the RGA
The Calibration Valve refers to the option of adding a Calibration Reference to
the CPM system. The Calibration Reference is located near the ion source.
NOTE: The Transpector emission and EM are turned off prior to opening
Calibration Valve (V5). This is due to trapped gas in the calibration
reference.
Sniffer or Capillary—The sniffer or capillary option allows sampling closer to
the actual process reactions and it gives a faster response time and better
signal (uses valve V2). Capillaries also provide part of the necessary pressure
drop to sample from atmospheric pressure.
CDG Gauge—The CDG gauge measures process pressure. It helps to
prevent accidental or erroneous inlet valves from being opened.
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