Method of calibrating a temperature measurement system

Abstract

A method of calibrating a temperature measurement system including the steps of heating a first substrate having a high emissivity value to a first process temperature; while the first substrate is at the first process temperature, calibrating a first probe and a second probe to produce temperature indications from the first substrate that are substantially the same, the first probe having associated therewith a first effective reflectivity and the second probe having associated therewith a second effective reflectivity, the first and second effective reflectivities being different; heating a second substrate having a low emissivity value to a second process temperature, the low emissivity value being lower than the high emissivity value; with the second substrate at the second process temperature, using both the first probe and the second probe to measure the temperature of the second substrate, the first probe producing a first temperature indication and the second probe producing a second temperature indication different from the first temperature indication; measuring a sensitivity of the temperature indication produced by the first probe to changes in substrate emissivity; and by using the measured sensitivity and the first and second temperature indications, computing a correction factor for the first probe, the correction factor to be applied to subsequent temperature readings of the first probe to produce corrected temperature readings.

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