Apparatus for substrate temperature measurement using a reflecting cavity and detector

A temperature sensor for measuring a temperature of a substrate in a thermal processing chamber, the chamber including a reflector forming a reflecting cavity with a substrate when the substrate is positioned in the chamber, the temperature sensor comprising:

• a probe having an input end positioned to receive radiation from the reflecting cavity, wherein radiation entering the probe includes reflected radiation emitted by the substrate and reflected by the reflector and non-reflected radiation emitted by the substrate and not reflected by the reflector, and wherein radiation exiting an output end of the probe includes a central portion and an outer portion;
• a reflective surface positioned to divide the radiation from the output end of the probe into a first beam containing the outer portion of the radiation and a second beam containing the central portion of the radiation, with a ratio of the reflected radiation to the non-reflected radiation being higher in the first beam than the second beam;
• a first detector to measure an intensity of the first beam to generate a first intensity signal;
• and
• a second detector to measure an intensity of the second beam and generate a second intensity signal.

An apparatus for measuring the temperature of a substrate in a thermal processing chamber, comprising:

• a reflector located to form a reflecting cavity with a substrate when the substrate is positioned in the chamber;
• a temperature sensor including a probe and a detector, the probe having an input end positioned to receive radiation from the reflecting cavity and an output end optically coupled to the detector, wherein the detector measures an intensity of a first portion of the radiation entering the probe to generate a first intensity signal and measures an intensity of a second portion of the radiation entering the probe to generate a second intensity signal, and wherein the radiation entering the probe includes reflected radiation emitted by the substrate and reflected by the reflector and non-reflected radiation emitted by the substrate and not reflected by the reflector and the temperature sensor is configured so that a ratio of the reflected radiation to the non-reflected radiation is higher in the first portion than the second portion;
• and
• a processor coupled to the detector to calculate a substrate temperature from the first and second intensity signals.

An apparatus for measuring the temperature of a substrate in a thermal processing chamber, comprising:

• a reflector located to form a reflecting cavity with a substrate when the substrate is positioned in the chamber;
• a temperature sensor including a probe having an input end positioned to receive radiation from the reflecting cavity, the radiation entering the probe including reflected radiation emitted by the substrate and reflected by the reflector and non-reflected radiation emitted by the substrate and not reflected by the reflector;
• means for directing a first portion of the radiation from an output end of the probe to a first detector and directing a second portion of the radiation from the output end of the probe to a second detector, wherein the directing means is configured so that a ratio of reflected radiation to non-reflected radiation is higher in the first portion than the second portion;
• and
• a processor coupled to the first and second detectors to calculate a substrate temperature from a first intensity signal from the first detector and a second intensity signal from the second detector.

A method of measuring the temperature of a substrate in a thermal processing chamber, comprising:

• positioning a substrate in a thermal processing chamber to form a reflecting cavity with a reflector located in the chamber;
• sampling radiation from the cavity with a probe and directing the sampled radiation to a detector, the sampled radiation including reflected radiation emitted by the substrate and reflected by the reflector and non-reflected radiation emitted by the substrate and not reflected by the reflector;
• generating a first intensity signal for a first portion of the sampled radiation with the detector;
• generating a second intensity signal for a second portion of the sample radiation with the detector, wherein a ratio of the non-reflected radiation to the reflected radiation is higher in the first portion than the second portion;
• and
• determining a temperature of the substrate from the first and second intensity signals.