Heat treatment method and heat treatment apparatus for heating substrate by irradiating substrate with light

1. A heat treatment apparatus for heating a substrate by irradiating a front surface of the substrate with light, the substrate including a known emissivity on a back surface thereof, the heat treatment apparatus comprising:

a chamber for receiving a substrate therein;

a holder for holding the substrate within said chamber;

an irradiation part for irradiating the front surface of the substrate held by said holder with light;

a quartz window provided in said chamber, for eliminating light having a predetermined wavelength range from light emitted from said irradiation part;

a photodetector element provided on the front surface side of said substrate, for receiving radiated light radiated from said front surface;

a filter for selectively allowing light having a selective wavelength range included in radiated light directed from the front surface of said substrate toward said photodetector element to pass therethrough, said selective wavelength range being included in said predetermined wavelength range;

a back-surface temperature measuring part provided on the back surface side of said substrate, for measuring a temperature of said back surface;

a radiated light intensity measuring part for measuring an intensity of the radiated light received by said photodetector element;

an emissivity calculating part calculating an emissivity of the front surface of said substrate after irradiation by said irradiation part is started and then the temperatures of the front and back surfaces of said substrate become equal to each other, based on the temperature of the back surface of said substrate measured by said back-surface temperature measuring part and the intensity of the radiated light from the front surface of said substrate measured by said radiated light intensity measuring part; and

a front-surface temperature calculating part for calculating the temperature of the front surface of said substrate heated by said irradiation, based on the emissivity of the front surface of said substrate calculated by said emissivity calculating part and the intensity of the radiated light from the front surface of said substrate measured by said radiated light intensity measuring part after said irradiation is started and before the temperature of the front surface of said substrate and the back surface thereof become equal to each other.

2. The heat treatment apparatus according to claim 1 , wherein

said radiated light intensity measuring part is configured to measure intensities of radiated light from the front surface of said substrate in chronological order after said irradiation is started, to thereby obtain a history of radiated light intensity, and

said front-surface temperature calculating part is configured to calculate a history of front-surface temperature of said substrate heated by said irradiation, based on said history of radiated light intensity.

3. The heat treatment apparatus according to claim 2 , wherein

said front-surface temperature calculating part is configured to calculate a maximum temperature at which the front surface of said substrate has reached from said history of front-surface temperature.

4. The heat treatment apparatus according to claim 1 , wherein

said irradiation part comprises a flash lamp for irradiating the substrate with a flash of light.

5. The heat treatment apparatus according to claim 1 , wherein

said photodetector element comprises an InSb photoconductive element.

6. The heat treatment apparatus according to claim 5 , wherein

said filter is a long-wave pass filter for selectively allowing light having a wavelength of 5 μm or more to pass therethrough.

7. A method of heating a substrate by irradiating a front surface of the substrate with light, the substrate including a known emissivity on a back surface thereof, the method comprising the steps of:

(a) eliminating light having a predetermined wavelength range from light emitted from an irradiation part and irradiating the substrate with the resultant light;

(b) selectively allowing light having a selective wavelength range included in radiated light from the front surface of said substrate to pass through, and receiving the light by a photodetector element, said selective wavelength range being included in said predetermined wavelength range;

(c) calculating an emissivity of the front surface of said substrate based on a temperature of the back surface of said substrate and an intensity of the radiated light from the front surface of said substrate received by said photodetector element, the temperature of the back surface being measured after the irradiation in said step (a) is started and then a temperature of the front surface of said substrate and the temperature of the back surface thereof become equal to each other; and

(d) calculating the temperature of the front surface of said substrate heated by said irradiation based on the emissivity of the front surface of said substrate calculated in said step (c) and the intensity of the radiated light from the front surface of said substrate received by said photodetector element after said irradiation is started and before the temperature of the front surface of said substrate and the back surface thereof become equal to each other.

8. The method according to claim 7 , wherein

in said step (d), intensities of radiated light from the front surface of said substrate after said irradiation is started are measured in chronological order to obtain a history of radiated light intensity, and a history of front-surface temperature of said substrate heated by said irradiation is calculated based on said history of radiated light intensity.

9. The method according to claim 8 , wherein

in said step (d), a maximum temperature that the front surface of said substrate has reached is calculated from said history of front-surface temperature.

10. The method according to claim 7 , wherein

in said step (a), a flash lamp emits the substrate with a flash of light.