Abstract: A method is provided, the method comprising preheating a rapid thermal processing chamber according to a preheating recipe and processing a first plurality of workpieces in the rapid thermal processing chamber. The method also comprises performing first parameter measurements on first and second workpieces of the first plurality of workpieces, the first parameter measurements indicative of first processing differences between the first and second workpieces, and forming a first output signal corresponding to the first parameter measurements. The method further comprises adjusting the preheating recipe based on the first output signal and using the adjusted preheating recipe to preheat the rapid thermal processing chamber for processing a second plurality of workpieces in the rapid thermal processing chamber to reduce second processing differences between first and second workpieces of the second plurality of workpieces.