| 摘要 |
After a substrate implanted with impurities is heated to a preheating temperature, the front surface of the substrate is heated to a target temperature by irradiating the front surface of the substrate with a flash of light. Further, the flash irradiation is continued to maintain the temperature of the front surface near the target temperature for a predetermined time period. At this time, a flash irradiation time period in the flash heating step is made longer than a heat conduction time period required for heat conduction from the front surface of the substrate to the back surface thereof, and a difference in temperature between the front and back surfaces of the substrate is controlled to be always not more than one-half of an increased temperature from the preheating temperature to the target temperature during the flash irradiation. This alleviates the concentration of stresses resulting from a difference in thermal expansion between the front and back surfaces of the substrate to thereby prevent the cracking of the substrate. |
