Ions of silicon are implanted into source/drain regions in a semiconductor wafer to amorphize an ion implantation region in the semiconductor wafer. A nickel film is deposited on the amorphized ion implantation region. First irradiation from a flash lamp is performed on the semiconductor wafer with the nickel film deposited thereon to increase the temperature of a front surface of the semiconductor wafer from a preheating temperature to a target temperature for a time period in the range of 1 to 20 milliseconds. Subsequently, second irradiation from the flash lamp is performed to maintain the temperature of the front surface of the semiconductor wafer within a ±25° C. range around the target temperature for a time period in the range of 1 to 100 milliseconds. This causes nickel silicide to grow preferentially in a direction perpendicular to the semiconductor wafer.