TEMPERATURE CONTROL METHOD

摘要

PURPOSE:To attain the proper temperature control in accordance with the temperature rise and fall characteristics despite the difference between the temperature rise and fall theories by changing the control characteristic of a linear controller in response to the error between a set temperature and the present temperature of a member to undergo the temperature control and to apparently obtain a non-linear controller. CONSTITUTION:A heating plate 11 is constituted of a metallic plate and a heating resistor 12 is buried into the plate 11. A semiconductor wafer is set on the plate 11 and heated up to a prescribed temperature. A positive/negative temperature error deciding circuit 22 decides a positive or negative temperature error. A switching circuit 23 is changed over based on the deciding output of the circuit 22. A computing part 21 obtains the controlled variables electric power supplied at the rise and the fall of temperature. Thus the control characteristic obtained at the rise of temperature has a gentler slope than that obtained at the fall of temperature in accordance with the difference between the resistance heating, i.e., a temperature rise theory and the natural cooling, i.e., a temperature fall theory. Then the optimum control of temperature is attained.