Thin Film Rate Monitor Calibration Technique
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
An invention would use two monitoring detectors to provide a reliable film deposition monitoring technique for thin film evaporators. An atomic absorption (AA) rate monitor would be used which would be continuously calibrated by a sampling and volume-reducing circular shuttered crystal monitor. This would reduce metal losses as well as eliminate the time-consuming recalibration and reprofiling procedures. AA rate monitors degrade from run to run due to the following reasons: 1. Filament degradation due to in situ sputtering 2. Filament degradation from normal use 3. Lens filter being coated with evaporant. To compensate for this, a crystal rate monitor with a shutter can be used to sample the rate, feed this information to the system computer and modify the filament current of the AA monitor, as required.