HEAT TREATMENT METHOD

The present invention provides a heat treatment method capable of accurately measuring the front surface temperature of a substrate. The semiconductor wafer is preheated by a halogen lamp and then heated by flash irradiation from a flash lamp. The temperature of the semiconductor wafer immediately before flash irradiation is measured by the lower radiation thermometer. Since the reception angle ofthe lower radiation thermometer with respect to the semiconductor wafer is 60-89 degrees, the lower radiation thermometer can accurately measure the temperature of the back surface of the semiconductor wafer regardless of the type of film formed on the back surface of the semiconductor wafer. During flash irradiation, the rising temperature of the front surface of the semiconductor wafer is measured by the upper radiation thermometer. The front surface temperature of the semiconductor wafer is calculated by adding the back surface temperature of the semiconductor wafer measured by the lower radiation thermometer and