Thermal measuring and testing – Temperature measurement – In spaced noncontact relationship to specimen
Reexamination Certificate
2000-03-16
2002-10-22
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Temperature measurement
In spaced noncontact relationship to specimen
C374S002000, C250S252100, C250S201200
Reexamination Certificate
active
06467952
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a virtual blackbody radiation system employing a light-emitting device, such as a light-emitting diode (hereinafter abbreviated to “LED”), and a radiation temperature measuring system employing the virtual blackbody radiation system.
2. Description of the Related Art
A short-time annealing process for annealing semiconductor wafers (hereinafter referred to simply as “wafers”) is one of processes for fabricating semiconductor devices. For example, a single-wafer lamp annealing device using a lamp as a heat source is used. The annealing device measures temperatures of regions in a surface of a wafer and regulates heating energy on the basis of measured temperatures to maintain a uniform temperature distribution in the surface f the wafer.
A noncontact radiation thermometer has been used for temperature measurement in recent years. The noncontact radiation thermometer is capable of avoiding metal contamination, which occurs when a thermocouple is used for measuring high temperatures exceeding 1000° C. due to metals, such as Fe, Cr and Ni, emitted by the sheath of the thermocouple, and is excellent in reactivity and accuracy. In a heat-processing environment in which the wafer is heated and cooled quickly, such as a short-time annealing process, the radiation thermometer has a tendency to drift. Therefore, the radiation thermometer needs calibration after the same has been used for a certain period of time.
Generally, a known radiation thermometer calibrating method measures the temperature of a standard blackbody furnace by a radiation thermometer, and compares a measured temperature of the standard blackbody furnace with the true temperature of the standard black furnace, and calibrates the radiation thermometer on the basis of the results of comparison. Another known radiation thermometer calibrating method uses, for calibration, virtual blackbody radiation at a predetermined temperature simulated by an LED by adjusting the intensity of light emitted by the LED instead of blackbody radiation radiated by a standard blackbody furnace.
When a standard blackbody furnace is used for calibrating a radiation thermometer, a long time in the range of 1 to two hours is necessary until the standard blackbody furnace stabilizes at a desired temperature. Therefore, more than half a day will be necessary for calibrating the radiation thermometer for five or more temperatures. The large, heavy blackbody furnace is inconvenient to use.
When virtual blackbody radiation is used, the driving current for driving the LED is regulated to make the LED emit light of a desired intensity to produce blackbody radiation corresponding to a predetermined temperature. Consequently, the LED is deteriorated rapidly and has a short life time. The radiation of the LED is unstable and the intensity of light emitted by the LED can be adjusted only in a narrow intensity range.
The present invention has been made in view of the foregoing problems and it is therefore an object of the present invention to provide a virtual blackbody radiation system capable of emitting light of a desired intensity without varying a driving current for driving a light source included therein, of extending the life time of the light source and having an improved radiation stability, and to provide a radiation thermometer employing the virtual blackbody radiation system.
SUMMARY OF THE INVENTION
With the foregoing object in view, the present invention provides a virtual blackbody radiation system including a light-emitting unit for emitting light of a fixed intensity in a direction along an optical axis; an optical unit for converging light emitted by the light-emitting unit in a convergent light; a photodetector disposed on the optical axis to receive the convergent light converged by the optical unit; and a focus adjusting unit for adjusting focus of the convergent light on the optical axis relative to the photodetector to adjust the intensity of the convergent light on the photodetector so that the intensity of the convergent light on the photodetector corresponds to that of radiation radiated by a blackbody of a predetermined temperature.
The present invention provides also a radiation temperature measuring system including a plurality of radiation thermometers; light receiving devices that receive light emitted by an object of measurement; a plurality of optical waveguides for guiding the light received by the light receiving devices to the radiation thermometers; a virtual blackbody radiation system for emitting modulated virtual blackbody radiation; and optical multiplexers for combining the light emitted by the object of measurement and guided by the optical waveguides and the virtual blackbody radiation radiated by the virtual blackbody radiation system.
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Kitamura Masayuki
Morisaki Eisuke
Shigeoka Takashi
Takahashi Nobuaki
Gutierrez Diego
Smith , Gambrell & Russell, LLP
Tokyo Electron Limited
Verbitsky Gail
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