Method and apparatus for real-time wafer temperature measurement using infrared pyrometry in advanced lamp-heated rapid thermal processors

摘要

A first and second pyrometer (26-28) are optically coupled by a light pipe (24) to a wafer (30) in an apparatus (10). The light pipe (24) passes through a shroud (16) of a heating lamp module (14). A computer (74) is interconnected to the pyrometers (26-28) and a lamp module power supply (80). A laser (48) emits a laser beam (50) through a power meter (86) onto an infrared mirror (56) over the light pipe (24). The mirror (56) directs the beam onto wafer (30) which reflects a portion of the beam back to the infrared mirror (56). The beam is then guided to an infrared photo-detector (58) which provides, in combination with the incident laser beam power meter (86), reflectance of the wafer surface for the laser beam which is related to wafer emissivity. The spectral infrared emissivity measurement can be performed more accurately over an extended temperature range if the transmissivity of the wafer is determined by another infrared photodetector (59) and both the measured wafer reflectance and transmissivity data are used to calculate the emissivity. Wafer emissivity data and pyrometers reading data are evaluated by the computer (74) to determine the true wafer temperature in real-time and to raise or lower the power output from the power supply (80) to adjust the wafer temperature within the apparatus (10).