Reduction of Process Variation Through Automated Substrate Temperature
Uniformity Mapping in Multi-Wafer MBE Systems

Thomas J. Rogers, Likang Li, Robert Yanka, Chris Santana
RFMD, 7628 Thorndike Rd., Greensboro, NC 27409, Email: trogers@rfmd.com, Phone: (336)678-8085
Jason R. Williams, Charles A. Taylor II, Darryl Barlett
k-Space Associates, Inc., 3626 W. Liberty Rd., Ann Arbor, MI 48103, www.k-space.com
Keywords: MBE, temperature measurement, temperature uniformity
Abstract
Measurement and control of substrate temperature is critical to the reduction of process variation when manufacturing compound semiconductor epiwafers. It is well known that the temperature of the substrate during growth can have a significant influence on physical properties of the semiconductor epilayers and the performance and yield of devices manufactured from those epiwafers. In this paper, we describe the application of an automated temperature measurement and mapping tool used to reduce growth temperature variation when manufacturing PHEMT and HBT epiwafers in RFMD’s MBE production facility. We present examples of detailed temperature maps acros multi-wafer platens of GaAs wafers with discussion of several causes of temperature variation. We also present a method for reducing run-to-run variation through automated substrate temperature setpoint adjustments.
 
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