INFICON TM-400 Thin Film Deposition Monitor - Manual (Page 51)

7 - 3
IP
N 17
88
0
0 Re
v.
B
TM-350/400 Operating Manual
The Modify up and Modify down keys are only active when a parameter is being
displayed. The parameters may be changed before, during, and after a deposition.
Only during a failure condition will the parameters be viewable but unchangeable.
7.4 Thickness Set Point Shutter Control
The TM-350 and the TM-400 provide a single shutter set point. The Thickness
Endpoint parameter establishes the film thickness at which the shutter will close.
As described above, depressing the START key zeros the Thickness Display and
opens the source shutter. The shutter is then automatically closed when the
thickness equals or exceeds the Thickness Endpoint parameter (unless S16
switch 7 is ON, in which case the shutter relay will activate for one second when
the Thickness Endpoint is reached.) If auto control of the shutter is not desired the
Thickness End Point parameter can be programmed at a value much greater than
can reasonably be achieved.
7.5 Crystal Test Display
To view the crystal test display, press the Display key until the TEST LED is
illuminated. With the Test display, the first digit of the Rate display shows the
current frequency setting (2=2.5, 3=3.0, 5-5.0, 6=6.0, 9=9.0 or 1=10.0 MHz). Refer
to
section 4.3.1 on page 4-4 to change the crystal type. The next digit is a dash [-]
where a blinking dash indicates the active sensor. The last two digits of the rate
show the crystal health for Sensor 1. Crystal health is indicated as a percentage of
crystal life remaining. A new crystal will have a health of 98 to 99%. The health
decreases as material is deposited on the crystal sensing surface.
The TM-400, will show the same information for Sensor 2 in the Thickness display.
Pressing the Display key again, until both the FREQ and the TEST LED’s are off,
will change the display back to rate and thickness. Displaying the Test function
does not affect the normal operation of the Monitor. In particular, both Thickness
and Rate continue to be calculated and the normal operation of the Thickness
Endpoint is not affected.
7.6 Crystal Fail Indication
As material builds up on the sensor crystal, a point will be reached at which the
crystal will no longer be able to support oscillation. At this point the crystal has
failed. The TM-400 will automatically switch to the backup sensor/crystal upon a
crystal failure and continue on from the last valid thickness. However, with the
TM-350 or if the backup sensor is failed, the monitor will indicate the crystal failure
by alternately flashing an "O FAIL" message with the normal display. The normal
display can still be changed using the Display key so that the last valid thickness
before the failure can be recorded. The source shutter closes and the Source
Shutter Indicator LED is turned off.