In-situ film thickness measurement using spectral interference at grazing incidence
First Claim
1. A method for in-situ measurement of the film thickness of a non-opaque film on a substrate, said method comprising:
- forming a plasma to deposit or etch said film;
collecting optical emissions, including those emitted from said plasma and reflected from said film on said substrate surface at grazing incidence;
determining a rate of interference within the reflected light; and
using said rate of interference to determine said film thickness.
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Abstract
A method and system using spectral interference of light from plasma emissions collected at near grazing incidence to in-situ monitor and control the film thickness of a non-opaque film. Embodiments of this invention are particularly useful to all substrate processing chambers equipped to form an in-situ plasma within the chamber and which are used to deposit or etch non-opaque films. One embodiment of the method of the present invention forms a plasma within a substrate processing chamber to deposit a non-opaque film on a wafer substrate within the chamber. During the plasma deposition process, a plurality of wavelengths of radiation including those reflected from the top and bottom layer of the film being deposited upon a wafer surface are collected through an existing viewport, and conveyed to a spectrometer for measurements via an optical fiber attached near this viewport. These measurements are analyzed to determine the film'"'"'s thickness. An alternate embodiment of the method of the present invention uses an interference filter to confine the spectral composition of the plasma emissions to an emission at a narrow wavelength interval and a photodiode to detect the intensity of the emission.
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Citations
24 Claims
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1. A method for in-situ measurement of the film thickness of a non-opaque film on a substrate, said method comprising:
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forming a plasma to deposit or etch said film;
collecting optical emissions, including those emitted from said plasma and reflected from said film on said substrate surface at grazing incidence;
determining a rate of interference within the reflected light; and
using said rate of interference to determine said film thickness. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A substrate processing system, said system comprising:
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a chamber having a chamber wall and a substrate support;
and a window positioned in an opening of said chamber wall such that an angle between a center of said window and said substrate support is at least 80 and less than 90 degrees inclusive as measured with respect to a normal to said substrate support, said system configured to in-situ measure a film thickness of a non-opaque film being processed in said chamber, where being processed is being deposited or etched. - View Dependent Claims (8)
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9. A substrate processing system, said system comprising:
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a chamber having a chamber wall and a substrate support;
a window positioned in an opening of said chamber wall such that an angle between a center of said window and said substrate support is at least 80 and less than 90 degrees inclusive as measured with respect to a normal to said substrate support;
an optical fiber configured to be coupled to said window and configured to convey plasma emissions generated from a plasma source within said chamber;
a light detection device to detect a rate of interference caused by the interference of said plasma emissions reflected from a top and a bottom of a substrate surface placed within said chamber;
and a data analysis device configured to analyze said rate of interference to provide wafer state data, said system configured to in-situ measure a film thickness of a non-opaque film being processed in said chamber, where being processed is being deposited or etched. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for in-situ control of the deposition of a non-opaque film on a substrate, said method comprising:
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forming a plasma;
depositing said film using said plasma;
while depositing the film, collecting optical emissions from said plasma reflected from said film at a grazing incidence angle of at least 80 and less than 90 degrees and counting periodic oscillations in plasma emissions caused by the interference of plasma emissions reflected from a top and a bottom of said film; and
stopping the deposition of said film once a predetermined oscillation count is reached. - View Dependent Claims (19, 20, 21)
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18. A method for in-situ control of the etching of a non-opaque film on a substrate, said method comprising:
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forming a plasma;
etching said film using said plasma;
while etching the film, collecting optical emissions from said plasma reflected from said film at a grazing incidence angle of at least 80 and less than 90 degrees and counting periodic oscillations in plasma emissions caused by the interference of plasma emissions reflected from a top and a bottom of said film; and
stopping the etching of said film once a predetermined oscillation count is reached. - View Dependent Claims (22, 23, 24)
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Specification