K465i Operations and Maintenance
P/N 1212831 Rev C
Page 4-40
Copyright
©
2012
Veeco Instruments, Inc. Confidential
All Rights Reserved
DESCRIPTION OF PYROCONTROL
To accommodate the 21 x 2” wafer carrier configuration used in the K465i GaN reactor,
three pyrometers are attached to viewports on the flow flange. As shown in Figure 4-10,
this configuration provides the pyrometers with a direct, unobstructed view of the carrier
surface.
Figure 4-10. Pyrometer Locations on Wafer Carrier
Corresponding to the properties of a typical SiC-coated graphite wafer carrier, each
pyrometer is preset to an emissivity of 0.76. During the growth runs, the direct readings
obtained by these pyrometers are fed back, along with their setpoints from the recipe
software, directly to the temperature controllers. Each heater zone is then quickly adjusted
to drive actual surface temperature to the relevant setpoint value. This control feedback
loop provides stable temperatures and stable power supply reading over the entire growth
of a complex structure. By this method, drift problems related with thermocouple use are
effectively removed, allowing for more stable process temperatures throughout the growth
run, and improved run-to-run repeatability.
