INFICON MDC-360C Thin Film Deposition Controller - Manual (Page 62)

MDC-360C DEPOSITION CONTROLLER
PROGRAMMING AND CONTROLLER SETUP 4-22
34. Sample Dwell% (000.0 to 100.0)
The Sample Dwell% parameter establishes the percentage of the Sample Time for
which the crystal is being sampled. Rate sampling is used for high deposition
thickness where crystal life is a problem. By sampling the rate periodically and
setting the power level to establish rate control, then closing the crystal shutter
and maintaining the power level, a large deposition thickness can be achieved
with one crystal. The primary sensor must have an individual shutter for the rate
sample feature. The default for this parameter is 100% which enables sampling at
all times.
35. Sample Period (0 to 9:59:59)
The Sample Period parameter defines the sample period. For example, a sample
time of 5 minutes and a dwell of 40% will result in the crystal being sampled for 2
minutes, then the crystal shutter is automatically closed for the remaining 3
minutes while the deposition power is kept constant. Please note, once the crystal
shutter has opened, there is a 5-second delay for crystal stabilization before
measuring. This parameter will not be displayed if this feature is disabled based
on the settings of the prior parameter.
36. Configure Sensors
Pressing the right arrow key from this point will bring you to the Configure
Sensors screen. In this screen you define which sensors are measured, the tooling
factors, etc. The following is a list the Configure Sensors parameters:
a. Tooling (10.0 to 499.9%)
This parameter sets the tooling factor for a particular sensor which is used to
compensate for geometric factors in the deposition system which result in a
difference between the deposition rate on the substrates and the rate on the
sensing crystal. This parameter is entered in percent units and 100% corresponds
to equal rates at the substrate and at the sensing crystal. To a first approximation
the tooling factor can be calculated using the following equation:
where:
dc= Distance from source to crystal.
ds= Distance from source to substrate.
The equation above assumes that the angle from normal between the source and
sensor and the source and substrate is zero. To account for the angle of the crystal
and the substrate, use the following equation:
Tooling
dc
ds
%
⎛
⎝
⎜
⎞
⎠
⎟ º
2
100