Light-irradiation type thermal processing method and thermal processing apparatus
From a stage of preheating by a halogen lamp to irradiation with a flash by a flash lamp, a radiation thermometer is used for measuring the temperature of a back surface of a semiconductor wafer. A increased temperature ΔT is determined by which the back surface of the semiconductor wafer is increased in temperature from the preheating temperature by irradiation with a flash. The specific heat of the semiconductor wafer has a known value. Further, the increased temperature ΔT is proportionate to the magnitude of energy applied to a front surface of the semiconductor wafer by irradiation with a flash. Thus, a front surface attained temperature of the semiconductor wafer can be determined using the increased temperature ΔT of the back surface of the semiconductor wafer during irradiation with a flash.
1. A thermal processing method for heating a substrate by irradiating said substrate having a front surface and a back surface with a flash, comprising the steps of:
(a) preheating said substrate by increasing said substrate in temperature to a predetermined preheating temperature before irradiating said substrate with a flash;
(b) heating said substrate increased in temperature to said preheating temperature by irradiating said front surface of said substrate with a flash;
(c) measuring an attained temperature of said back surface after said irradiating with a flash and calculating a difference temperature between said attained temperature of said back surface of said substrate and said preheating temperature; and
(d) determining a front surface attained temperature of said front surface of said substrate based on said difference temperature.
2. The thermal processing method according to claim 1 , further comprising the steps of:
(e) storing a correlation table of said front surface attained temperature and said difference temperature, wherein
in said step (d), said front surface attained temperature is calculated from said difference temperature based on said correlation table.
3. The thermal processing method according to claim 1 , wherein
in said step (d), said front surface attained temperature is calculated based on an integral of said difference temperature.