Optical phase measurement method and system

Patent metadata

Field	Value
Publication number	US-12467879-B2
Application number	US-202418595292-A
Country	US
Kind code	B2
Filing date	Mar 4, 2024
Priority date	Apr 7, 2014
Publication date	Nov 11, 2025
Grant date	Nov 11, 2025

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.

First claim

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 is configured to provide spectral phase retrieval, comprises a beam splitter, and 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 while maintaining a fixed distance between at least a portion of the reference reflector and the beam splitter; the detection unit comprises a two dimensional sensor configured and operable for detecting a combined light beam formed by a light beam reflected from said reflector and a light beam reflected from a sample as a result of an illumination of the sample with a line of light, and generating measured data that comprises spectrograph data that is 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 . The measurement system according to claim 1 , wherein the reference reflector is tillable about an axis of rotation.

3 . The measurement system according to claim 1 , that is configured to perform a single dimension imaging of the sample on one axis of the two dimensional sensor and to unfold a spectrum of each imaging pixel on to second axis of the two dimensional sensor.

4 . The measurement system according to claim 1 , comprising a sample support configured to orient the sample in relation to the optical system.

5 . The measurement system according to claim 1 , wherein the combined light beam is polarized.

6 . The measurement system according to claim 1 , configured to apply an illumination channel polarization independently from a collection channel polarization.

7 . The measurement system according to claim 1 , configured to preform cross-polarization measurements.

8 . The measurement system according to claim 1 , configured to change a focus state of the combined light beam.

9 . 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; the interferometric optical system belongs to a measurement system configured to provide spectral phase retrieval; detecting, by a two dimensional sensor of a detection unit, a combined light beam formed by a light beam reflected from a reflector in the reference arms and a light beam reflected from a sample as a result of an illumination of the sample with a line of light, wherein the directing and the detecting are executed while maintaining a fixed distance between at least a portion of a reference reflector and the beam splitter of the interferometric optical system; generating measured data that comprises spectrograph data that is 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.

10 . The method according to claim 9 , comprising tilting the reference reflector about an axis of rotation.

11 . The method according to claim 9 , comprising performing a single dimension imaging of the sample on one axis of the two dimensional sensor and unfolding a spectrum of each imaging pixel on to second axis of the two dimensional sensor.

12 . The method according to claim 9 , comprising orienting, by a sample support, the sample in relation to the optical system.

13 . The method according to claim 9 , wherein the combined light beam is polarized.

14 . The method according to claim 9 , comprising applying an illumination channel polarization independently from a collection channel polarization.

15 . The method according to claim 9 , comprising preforming cross-polarization measurements.

16 . The method according to claim 9 , comprising changing a focus state of the combined light beam.

Assignees

• Nova Ltd

Inventors

• Barak Gilad
• Grossman Danny
• Shafir Dror
• Berlatzky Yoav
• Hainick Yanir

Classifications

• G01N2021/8848

  Polarisation of light · CPC title

• G01N21/8806

  Specially adapted optical and illumination features · CPC title

• G01B11/0675

  using interferometry · CPC title

• G01J3/4535

  Devices with moving mirror (G01J3/4532 takes precedence) · CPC title

• G01B2290/70

  Using polarization in the interferometer · CPC title