Infrared laser interferometric thermometry: Extension to batch processing environments

Abstract

Infrared laser interferometric thermometry (IRLIT) is a noncontact technique for measuring the temperature of single semiconductor substrates (with polished front and back surfaces) from thermally induced changes in wafer thickness and refractive index. It is suggested that IRLIT can be extended to a batch processing environment by making use of antireflection coatings for all but the wafer(s) of interest. This concept is tested with an IRLIT measurement of the temperature of a bare Si wafer sandwiched between several AR-coated Si wafers stacked on a hotplate. The data for this generic wafer arrangement confirm the applicability of IRLIT to situations such as temperature measurement of selected-position wafers in fully loaded boats during heating or cooling in a tube furnace. © 1995 American Institute of Physics.