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US 6,236,459 B1Granted
Thin film measuring device and method
AssigneeUniversity of Miami
InventorsShahriar Negahdaripour, Ali Khamene
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Abstract
An interferometric thin film measuring device has a source of illumination light, a detector disposed in a return path of light reflected from a specimen of illumination light, a plurality of wavelength filters that filter light into image channels, a weight vector calculating device that receives detected signals, a look-up table storage unit that stores calibration weight vectors, a weight vector comparing unit that compares calibration weight vectors from the look-up table storage unit to subject weight vectors, and a data output/storage unit to output the measured thin film values.
Claims34
An interferometric method of determining a thin-film thickness, comprising:
- selecting a plurality of calibration thin films, each having a predetermined film thickness;
- illuminating each of said plurality of calibration thin films with light having substantially predetermined intensity and spectral characteristics and a coherence length approximately equal to or longer than each corresponding predetermined film thickness;
- filtering light reflected from each of said plurality of calibration thin films with a plurality of wavelength filters;
- detecting light in a plurality of image channels, wherein each image channel of said plurality of image channels contains light output from a respective one of said wavelength filters;
- determining a plurality of calibration weight vectors for each of a plurality of look-up thicknesses within a range of look-up thicknesses that includes at least some of said predetermined film thicknesses of said plurality of calibration thin films, said calibration weight vectors collectively containing both frequency and intensity information of said light reflected from said plurality of calibration thin films;
- generating a calibrated look-up table comprising said calibration weight vectors;
- illuminating a subject thin film with light having said substantially predetermined intensity and spectral characteristics and said coherence length;
- filtering light reflected from said subject thin film with each of said plurality of wavelength filters;
- detecting light in a plurality of image channels, wherein each image channel of said plurality of image channels contains light output from a respective one of said wavelength filters after said filtering light reflected from said subject thin film;
- determining a subject weight vector from light detected from said plurality of image channels of said subject thin film;
- selecting a calibration weight vector from said look-up table that is substantially the most equivalent calibration weight vector to said subject weight vector;
- and
- determining said subject thin-film thickness from said selected calibration weight vector.
10 more elements
An interferometric thin film measuring device, comprising:
- a source of illumination light;
- a detector disposed in a return path of light reflected from a specimen disposed in a path of said illumination light;
- a plurality of wavelength filters disposed in said return path of light reflected from said specimen between said specimen and said detector;
- a weight vector calculating device in communication with said detector;
- a look-up table storage unit in communication with said weight vector calculating device;
- a weight vector comparing unit in communication with said look-up table storage unit and said weight vector calculating device;
- and
- a data output unit in communication with said weight vector comparing unit.
5 more elements
An interferometric method of determining a thin-film thickness, comprising:
- illuminating a subject thin film with light having substantially predetermined intensity and spectral characteristics and coherence length;
- filtering light reflected from said subject thin film with each of a plurality of wavelength filters;
- detecting light in a plurality of image channels, wherein each image channel of said plurality of image channels contains light output from a respective one of said wavelength filters after said filtering light reflected from said subject thin film;
- determining a subject weight vector from light detected from said plurality of image channels of said subject thin film;
- selecting a calibration weight vector from a look-up table comprising a plurality of calibration weight vectors, said calibration weight vector being substantially the most equivalent calibration weight vector to said subject weight vector;
- and
- determining said subject thin-film thickness from said selected calibration weight vector.
4 more elements
Dependencies are inferred from the claim text.