Method for the controlled variation of a temperature gradient in a substrate while holding constant a prescribable mean temperature

摘要

In this method, the temperature (T) and its gradient (dT/dx) are set by means of thermal radiation which is generated by two heatable surfaces (3, 4) arranged on two mutually opposite sides of the substrate (1). Furthermore, the mean temperature (T) of the substrate is measured and fed as actual value (TI) in addition to a prescribable desired value (TS) to a controller (10) whose output signal (TR) is used to control the heating power of the two heatable surfaces (3, 4) and, in addition, is amplified separately for each heatable surface (3, 4) by a weighting factor (G1, G2) assigned to the respective surface (3, 4). A previously produced calibration graph or a calibration table are used, taking account of the desired value (TS) of the mean temperature (T) relating to the respectively prescribed instantaneous value (dT/dx(t)) of the temperature gradient (dT/dx), to determine the weighting factors (G1, G2). <IMAGE>