In-situ film thickness measurement using spectral interference at grazing incidence

A substrate processing system, said system comprising:

• 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.

A method for in-situ control of the deposition of a non-opaque film on a substrate, said method comprising:

• 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.

A method for in-situ control of the etching of a non-opaque film on a substrate, said method comprising:

• 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.