A calibration method for determining temperature set point corrections to be applied to the nominal temperature set points of each of the N heating zones of a heat treatment unit having L substrate locations, includes the following steps: establishing a sensitivity model linking variations of a substrate characteristic at each of M representative locations of the L locations to temperature set point variations applied in each of the N heating zones, the variations respectively reflecting differences with respect to a target characteristic and with respect to the nominal set points; executing the process in the heat treatment unit and on the basis of nominal set points; measuring the substrate characteristic at least at a representative measurement location of each heating zone of the unit to supply M measurements; and determining temperature set point corrections from the sensitivity model, the measurements and the target substrate characteristic.