Apparatus and method for real time measurement of substrate temperatures for use in semiconductor growth and wafer processing
First Claim
1. In an apparatus for measuring the temperature of a substrate material by inference from its bandgap measured by diffuse reflectivity comprising lamp means for emitting broad spectrum white light, focusing means for focusing the white light upon a surface of a substrate material, detector means positioned at a non-specular position on the front side of said substrate material and computing means for determining the temperature dependent bandgap absorption from onset wavelength of non-specular reflection from a surface of the substrate material, the improvement comprising:
- single optical fiber means for collecting non-specularly reflected light detected by said detector means.
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Abstract
The invention is an optical method and apparatus for measuring the temperature of semiconductor substrates in real-time, during thin film growth and wafer processing. Utilizing the nearly linear dependence of the interband optical absorption edge on temperature, the present method and apparatus result in highly accurate measurement of the absorption edge in diffuse reflectance and transmission geometry, in real time, with sufficient accuracy and sensitivity to enable closed loop temperature control of wafers during film growth and processing. The apparatus operates across a wide range of temperatures covering all of the required range for common semiconductor substrates.
38 Citations
17 Claims
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1. In an apparatus for measuring the temperature of a substrate material by inference from its bandgap measured by diffuse reflectivity comprising lamp means for emitting broad spectrum white light, focusing means for focusing the white light upon a surface of a substrate material, detector means positioned at a non-specular position on the front side of said substrate material and computing means for determining the temperature dependent bandgap absorption from onset wavelength of non-specular reflection from a surface of the substrate material, the improvement comprising:
single optical fiber means for collecting non-specularly reflected light detected by said detector means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 17)
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13. The method of measuring the temperature of a substrate material by inference from its bandgap measured by diffuse reflectivity comprising:
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A. Generating a broad spectrum of light by light-producing means;
B. Directing said light upon a front surface of a substrate material whereby a portion of said light is non-specularly reflected from at least one surface of said substrate;
C. Collecting at least a portion of said non-specularly reflected light at at least one focusing mirror;
D. Selecting at least a portion of said collected light to a single optical fiber means;
E. Transmitting said at least a portion of said non-specularly reflected light through said optical fiber means to a spectrometer; and
F. Analyzing said non-specular reflected light to improve band edge definition. G. Mapping the surface temperature of the wafer by detector scanning stage means. - View Dependent Claims (15)
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14. The method of measuring the temperature of a substrate material by inference from its bandgap measured by diffuse reflectivity comprising:
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A. Generating a broad spectrum of light by light-producing means;
B. Directing said light upon a front surface of a substrate material whereby a portion of said light is non-specularly reflected from at least one surface of said substrate;
C. Collecting at least a portion of said non-specularly reflected light at at least one focusing lens;
D. Selecting at least a portion of said collected light to a single optical fiber means;
E. Transmitting said at least a portion of said non-specularly reflected light through said optical fiber means to a spectrometer; and
F. Analyzing said non-specular reflected light to improve band edge definition. G. Mapping the surface temperature of the wafer by detector scanning stage means. - View Dependent Claims (16)
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Specification