Apparatus and method for measuring the surface temperature of a substrate

Apparatus suitable for measuring a surface temperature of a substrate having a substantially planar processed surface, said apparatus comprising:

• a light source configured to illuminate a treated zone of the processed surface of the substrate with a pulsed light beam;
• a first illumination system emitting a first beam of probing light at a first wavelength of probing light towards said treated zone of the processed surface of the substrate;
• a first optical system configured to:
• collect a first radiated beam of thermal radiation radiated by a locally heated area in said treated zone over a first solid angle of thermal radiation in a first direction of thermal radiation;
• and transmit said first radiated beam to a first detection channel of thermal radiation adapted to deliver a first signal of thermal radiation representative, at a first instant, of a first intensity of the first radiated beam within a first bandwidth around a first wavelength of thermal radiation;
• and
• collect a first reflected beam of probing light reflected by said treated zone over a first solid angle of probing light in a first direction of probing light;
• and transmit said first reflected beam to a first detection channel of probing light adapted to deliver a first signal of probing light representative, at a second instant, of a first intensity of the first reflected beam at said first wavelength of probing light;
• and
• processing means configured to:
• process said first signal of thermal radiation and said first signal of probing light;
• and
• determine said surface temperature of the treated zone at said first instant based on said first processed signal of thermal radiation and said first processed signal of probing light;
• wherein:
• said first detection channel of thermal detection includes:
• a first detector of thermal radiation sensitive to said first wavelength of thermal radiation;
• and
• a first routing means of thermal radiation to route the first radiated beam to the first detector of thermal radiation;
• and
• said first detection channel of probing light includes:
• a first detector of probing light sensitive to said first wavelength of probing light;
• and
• a first routing means of probing light to route the first reflected beam to the first detector of probing light,
• said first wavelength of thermal radiation is selected to be equal to said first wavelength of probing light;
• said first detection channel of thermal radiation and said first detection channel of probing light are synchronized so that said first instant and said second instant occur at the same time;
• said first routing means of thermal radiation is arranged in relation with said first routing means of probing light to prevent the first detector of thermal radiation from receiving part of the first reflected beam of probing light, wherein said first direction of thermal radiation is separated from said first direction of probing light by a first angle of deviation greater than zero and lower than a first predetermined threshold.