INFICON MDC-370 Thin Film Deposition Controller - Manual (Page 128)

MDC-370 DEPOSITION CONTROLLER
10.6.2 TOOLING FACTOR
Having established the film density, the material and the sensor tooling factors
should be established next. For the MDC-370, it is typical to keep the material
tooling factor equal to 100% and only use the sensor tooling factors 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 way, each sensor's individual rate, as displayed in the
Source/Sensor Status Screen, will represent the rate on the substrates. This will
make it easy to identify any changes in the vapor distribution since all sensor
should display the same rate once calibrated.
To do the sensor calibration, place several test substrates at representative
locations in the deposition fixture and change the crystals in the sensors head or
heads that you wish to calibrate for this material. Go to the material selection
menu and select the material you wish to calibrate. Set the material conditioning
parameters as well as the desired deposition rate if not set already. Also, enter the
Configure Sensors parameters to select which sensors will be used to measure this
material.
Next, scroll down to Calibrate Sensors and press the right arrow key to get to the
Calibrate Sensors screen. Enter the desired calibration thickness and press the
Start key to start the calibration run. The calibration thickness should as thick or
thicker as you’re actual coatings.
Once started, the 370 will condition the source as programmed, open the source
shutter and deposit until the calibration thickness is reached as displayed in the
main thickness display.
Once the calibration run is complete, determine the average film thickness on the
test substrates by using an alternate measurement device such as a surface
profilometer. Enter the measured substrate thickness in the Measured Thickness
field in the Calibration Screen and press Enter. The MDC-370 will calculate the
new tooling factors for all sensors enabled during calibration. The new sensor
tooling factors will be displayed in the NewTlng field in the calibration screen.
The 370 will then ask the user if the new tooling factors should be saved.
10.6.3 ACOUSTIC IMPEDANCE
Establishment of the acoustic impedance requires that the crystal be heavily
loaded. Continue to deposit on the sensor crystal until the crystal health
approaches 50% or until the crystal is approaching the end of its useful life.
Deposit another trial run as above but this time use the manual power mode
instead of the automatic mode. Measure the average film thickness on the test
substrates and this adjust the acoustic impedance parameter up or down to bring
the displayed thickness into agreement with the measured thickness. This
calibrates the acoustic impedance parameter.
The MDC-370 is now fully calibrated for the film in question and should produce
consistent and accurate films.
THEORY OF OPERATION 10-6