In-situ thickness and refractive index monitoring and control system for thin film deposition

An apparatus for determining at least one of thickness and refractive index of an optical thin film, the apparatus comprising:

• a) an optical source that generates a diagnostic light beam having a first and a second wavelength;
• b) a substrate support including a first, second, and third region, each of the first, second, and third regions being positioned to receive the diagnostic light beam and being adapted to attenuate the diagnostic light beam with a different attenuation, and one of the first, second, and third regions being adapted to support a substrate having an optical thin film;
• c) at least one detector positioned to receive the diagnostic light beam after transmission through each of the first, second, and third regions, the at least one detector adapted to measure light intensity of the diagnostic light beam after transmission through the first, second, and third regions;
• and
• d) a processor that determines at least one of the thickness and the refractive index of the optical thin film by solving a first and a second normalized intensity function for at least one of thickness and refractive index, the first and the second normalized intensity function being determined from the measured light intensity of the diagnostic light beam after transmission through the first, second and third regions.

A method of measuring at least one of thickness and refractive index of an optical thin film, the method comprising:

• a) generating a diagnostic light beam having a first and a second wavelength;
• b) measuring light intensities at the first and the second wavelength of the diagnostic light beam;
• c) measuring light intensities at the first and the second wavelength of the diagnostic light beam after transmission through the optical thin film;
• d) measuring null light intensities at the first and the second wavelength of the diagnostic light beam;
• e) determining a first and a second normalized intensity function from the measured light intensities of the diagnostic light beam at the first and the second wavelength, the measured light intensities of the diagnostic light beam at the first and the second wavelength after transmission through the optical thin film and the measured null light intensities of the diagnostic light beam at the first and second wavelength;
• and
• f) determining at least one of the thickness and the refractive index of the optical thin film by solving the first and second normalized intensity function for at least one of thickness and refractive index.

A deposition system comprising:

• a) a deposition source tat deposits an optical thin film on a substrate;
• b) an optical source that generates a diagnostic light beam having a first and a second wavelength;
• c) a substrate support including a first, second, and third region, each of the first, second, and third regions being positioned to receive the diagnostic light beam and being adapted to attenuate the diagnostic light beam with a different attenuation, and one of the first, second, and third regions being adapted to support the substrate;
• d) at least one detector positioned to receive the diagnostic light beam after transmission through each of the first, second, and third regions, the at least one detector adapted to measure light intensity of the diagnostic light beam after transmission through the first, second, and third regions;
• e) a processor that generates a signal by solving a first and a second normalized intensity function for at least one of thickness and refractive index, the fast and the second normalized intensity function being determined from the measured light intensity of the diagnostic light beam after transmission through the first, second, and third regions;
• and
• f) a deposition controller that is electrically connected to the processor and to the deposition source, the deposition controller adjusting at least one deposition parameter of the deposition source in response to the signal generated by the processor to control the at least one of thickness and refractive index of the optical thin film on the substrate.