INFICON SID-242 Thin Film Deposition Controller - Manual (Page 70)

Chapter 4 SQM-142 Card
4-8
The Sensor Readings display should show 5.5 MHz, very stable. If not, contact Sigma
Instruments technical support.
When a stable frequency reading is achieved with the test oscillator, reconnect the
sensor and verify a stable reading.
When stable sensor readings are achieved without deposition, reconnect the source
supply. Start the deposition process in Manual mode with 0% output. The % Life
readings should remain stable.
Slowly raise the % Output until a rate reading is displayed in Sensor Readings. As
material is deposited on the crystal, the % Life reading should remain stable, or drop
slowly and consistently. If not, check your source supply for erratic output. Also assure
that the sensor is not too close to the source (particularly in sputtering).
4.4.2 Incorrect Rate or Thickness Measurement:
First, complete the procedures in Section 4.4.1 to assure reliable sensor operation.
Set Tooling as described in the Edit Process section of Chapter 3. Incorrect Tooling
values will cause consistently low or high rate/thickness values for a material.
Verify that the Material Density and Z-Factor values match those in the Materials
Parameters Appendix. If the material is not listed, check a materials handbook. Density
has a significant effect on rate/thickness calculations.
Z-Factor corrects for stresses as a crystal is coated. If readings are initially accurate,
but deteriorate as crystal life drops below 60-70%, you need to adjust the Z-Factor or
replace crystals more frequently. The relationship between Z-Factor and Acoustic
Impedance is discussed in the Materials Appendix.
2.8.3 Poor Rate Stability:
First, be sure that a stable rate can be achieved in Manual mode, as explained in
Section 4.4.1. Once a stable rate is achieved in Manual mode, follow the Loop Tuning
procedures of Section 4.5.