Optical phase measurement method and system

Abstract

A measurement system for use in measuring parameters of a patterned sample, the system including a broadband light source, an optical system configured as an interferometric system, a detection unit, and a control unit, where the interferometric system defines illumination and detection channels having a sample arm and a reference arm having a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms, the detection unit for detecting a combined light beam formed by a light beam reflected from the reflector and a light beam propagating from a sample's support, and generating measured data indicative of spectral interference pattern formed by spectral interference signatures, and the control unit for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample.

We claim: 
     
         1 . A measurement system for use in measuring parameters of a patterned sample, the system comprising: a broadband light source; an optical system configured as an interferometric system; a detection unit; and a control unit; wherein the interferometric system defines illumination and detection channels having a sample arm and a reference arm comprising a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms; the detection unit comprises a configured and operable for detecting a combined light beam formed by a light beam reflected from said reflector and a light beam propagating from a sample's support, and generating measured data indicative of spectral interference pattern formed by at least two spectral interference signatures; and said control unit is configured and operable for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample. 
     
     
         2 . A method for use in measuring parameters of a patterned sample, the method comprising: directing broadband light through an interferometric optical system having a sample arm and a reference arm with an optical path difference between the sample and reference arms; detecting a combined light beam formed by a light beam reflected from a reflector in the reference arms and a light beam propagating from the sample under measurements, and generating measured data indicative of spectral interference pattern formed by at least two spectral interference signatures; and applying a model-based processing to the spectral interference pattern and determining one or more parameters of the pattern in the sample.