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US 7,612,891 B2Granted
Measurement of thin films using fourier amplitude
AssigneeVeeco Instruments Inc.
InventorDer-Shen Wan
Life of this patent
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Abstract
Thin-film thickness and refractive index are measured using the Fourier amplitude of a broadband interferometric spectrum. Due to the smooth nature of the Fourier amplitude as a function of wavelength, as compared to the fast varying Fourier phase conventionally used to measure thickness, increased stability and repeatability of measurement are achieved. As a result, measurements of ultra-thin films with thickness below 100 nm are possible with reliable results.
Claims22
A method for determining a property of a thin film placed over a substrate, comprising the following steps:
- producing a test correlogram of said thin film over the substrate;
- generating a test linear transform of the test correlogram and extracting a test transform amplitude from the test linear transform;
- deriving a test-beam amplitude component of said test transform amplitude by removing a reference amplitude function, wherein the reference amplitude function comprises the product of the amplitude components contributed by the light source and the reference beam;
- and
- finding a value of said property of the thin film by comparing said test-beam amplitude component to a model test-beam amplitude function.
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Dependencies are inferred from the claim text.