Optical method and system for measuring isolated features of a structure

Patent metadata

Field	Value
Publication number	US-10073045-B2
Application number	US-201314416723-A
Country	US
Kind code	B2
Filing date	Jul 24, 2013
Priority date	Jul 24, 2012
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

An optical method and system are presented for use in measurement of isolated features of a structure. According to this technique, Back Focal Plane Microscopy (BFM) measurements are applied to a structure and measured data indicative thereof is obtained, wherein the BFM measurements utilize dark-field detection mode while applying pinhole masking to incident light propagating through an illumination channel towards the structure, the measured data being thereby indicative of a scattering matrix characterizing scattering properties of the structure, enabling identification of one or more isolated features of the structure.

First claim

The invention claimed is:

1. An optical method for use in measurement of isolated features of a structure, the method comprising:
performing Back Focal Plane Microscopy (BFM) measurements to the structure and obtaining measured data indicative of scattering properties of the structure with respect to incident light, wherein said BFM measurements are performed using dark-field detection mode, while applying pinhole masking to incident light propagating through the illumination channel towards the structure, wherein said dark-filed detection mode comprises affecting polarization of light passing along the illumination and detection channels by passing the incident light and collected returned light through respectively first and second polarizers accommodated in the illumination and detection channels and having substantially parallel planes of polarization, and passing the incident polarized light propagating towards the structure through a phase retarder, and passing the returned light propagating from the structure to the second polarizer through said phase retarder, such that the measured data corresponding to detected signals from the structure is indicative of a scattering matrix characterizing scattering properties of the structure with respect to the incident light; and
processing the measured data using a data processor, said processing comprising applying a fitting procedure between the measured and theoretical modeled data, and identifying an isolated feature of the structure from a best fit condition between the measured and theoretical data.

2. The method according to claim 1 , wherein said applying of the pinhole masking to the incident light propagating through the illumination channel comprising scanning a Fourier plane of the structure plane by a pinhole and successively collecting light components returned from the structure, and generating the measured data being indicative of at least amplitude of a scattering matrix, S(k in ,k out ), characterizing the structure, where k in and k out are incident and returned ray vectors respectively.

3. The method according to claim 2 , wherein the measured data, corresponding to a detected signal from the structure, is proportional to amplitude of the scattering matrix, |S(k′ in ,k out )| 2 .

4. The method according to claim 3 , wherein said scanning of the Fourier plane by the pinhole comprises moving said pinhole with respect to an additional static pinhole located in the Fourier plane, and generating the measured data being indicative of the amplitude and a phase of the scattering matrix characterizing the structure.

5. The method according to claim 4 , wherein said measured data corresponds to a sum |S(k 1 ,k out )+S(k 2 ,k out )| 2 of scattering matrices S(k 1 ,k out ) and S(k 2 ,k out ) and corresponding to measurements through the static and the movable pinholes respectively, k 1,2 being two incident ray vectors, the processing of the measured data comprising utilizing the determined amplitude and extracting the phase between the two matrices S(k 1 ,k out ) and S(k 2 ,k out ).

6. An optical method for use in measurement of isolated features of a structure, the method comprising:
performing Back Focal Plane Microscopy (BFM) measurements on the structure and obtaining measured data indicative of scattering properties of the structure with respect to incident light, wherein said BFM measurements are performed using dark-field detection mode, while applying pinhole masking to incident light propagating through an illumination channel towards the structure, wherein said applying of the pinhole masking comprising scanning a Fourier plane of the structure plane by moving a pinhole defined in a pinhole mask with respect to an additional static pinhole located in the Fourier plane and successively collecting light components returned from the structure, and generating the measured data being indicative of amplitude and phase of a scattering matrix, S(k in ,k out ), characterizing the structure, where k in and k out are incident and returned ray vectors respectively, wherein said measured data corresponds to a sum |S(k 1 ,k out )+S(k, 2 ,k out )| 2 of scattering matrices S(k 1 ,k out ) and S(k 2 ,K out ) corresponding to measurements through the static and the movable pinholes respectively, k 1,2 being two incident ray vectors; and
processing the measured data using a data processor, said processing comprising utilizing the determined amplitude |S(k′ in ,k out )| 2 of the scattering matrix as being proportional to the detected light and extracting the phase between the two matrices S(k 1 ,k out ) and S(k 2 ,k out ), and in accordance with the extracted phase, identifying an isolated feature of the structure.

7. The method according to claim 6 , wherein said applying of the dark-field detection mode comprises affecting polarization of light passing along the illumination and detection channels.

8. The method according to claim 7 , wherein said affecting of the polarization of light passing along the illumination and detection channels comprises passing the incident light and collected returned light through respectively first and second polarizers accommodated in the illumination and detection channels and having substantially perpendicular planes of polarization.

9. The method according to claim 7 , wherein said affecting of the polarization of light passing along the illumination and detection channels comprises passing the incident light and collected returned light through respectively first and second polarizers accommodated in the illumination and detection channels and having substantially parallel planes of polarization, and passing the incident polarized light propagating towards the structure through a phase retarder, and passing the returned light propagating from the structure to the second polarizer through said phase retarder.

10. The method according to claim 7 , wherein said affecting of the polarization of light passing along the illumination and detection channels comprises passing the incident light and collected returned light through a common polarizer and a common phase retarder accommodated in a spaced-apart relationship in a common portion of the illumination and detection channels, with the polarizer being located upstream of the phase retarder with respect to a direction of propagation of the incident light to the structure along the illumination channel.

11. An optical method for use in measurement of isolated features of a structure, the method comprising:
performing Back Focal Plane Microscopy (BFM) measurements on the structure and obtaining measured data indicative of scattering properties of the structure with respect to incident light, wherein said BFM measurements are performed using dark-field detection mode, while applying pinhole masking to incident light propagating through the illumination channel towards the structure, wherein said dark-filed detection mode comprises affecting polarization of light passing along the illumination and detection channels by passing the incident light and collected returned light through a common polarizer and a common phase retarder accommodated in a spaced-apart relationship in a common portion of the illumination and detection channels, with the polarizer being located upstream of the phase retarder with respect to a direction of propagation of the incident light to the structure along the illumination channel; and
processing the measured data using a data processor, said processing comprising applying a fitting procedure between the measured and theoretical modeled data, and identifying an isolated feature of the structure from a best fit condition between the measured and theoretical d

Assignees

• Nova Measuring Instr Ltd

Inventors

• Barak Gilad
• Hainick Yanir
• Shafir Dror

Classifications

• G01N2201/0683

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• G01N21/9501 Primary

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