Patent ID: 8476561
Filing Date: 2013-07-02
Classification: F27D,H01L

Abstract:
1. A substrate heating device for heating a substrate by a lamp heating device, comprising: a power source; a capacitor charged by the power source; a flash lamp that discharges by electrical charges accumulated in the capacitor; an inductance connected between the capacitor and the flash lamp; a trigger unit causing the flash lamp to start discharging, wherein the substrate heating device comprises: a diode connected in parallel to a series circuit composed of the flash lamp and the inductance, a semiconductor switch connected in series to the flash lamp, and a control unit for controlling on/off of the semiconductor switch; wherein the control unit has a drive circuit for outputting a first drive signal causing the semiconductor switch to turn on and off at least once after a trigger signal is input into the trigger unit, and for outputting a second drive signal causing the semiconductor switch to turn on only once after the first drive signal is output; and wherein a time period during which the second drive signal causes the semiconductor switch to turn on is longer than that a drive signal of the first drive signals causes the semiconductor switch to turn on; wherein the first drive signal is an on-off signal of which an on signal causes the semiconductor switch to keep in the on-state and an off signal causes the off-state to alternately be produced more than once; wherein a duty ratio of the on-off signal, defined as the period of the on signal divided by the sum of the period of on signal plus the period of the off signal, is changed during the time when the first drive signal is output such that a temperature difference between a top surface and a bottom of said substrate amounts to at least a temperature difference where an ion diffusion is not spread throughout the entire substrate, and amounts to a temperature difference range at which no adverse effect by thermal strain is effected, and wherein the second drive signal is adapted to increase the surface temperature of said substrate to a desired temperature which is higher than the temperature at the top surface obtained by said first dive signal.