Optical phase measurement method and system

Patent metadata

Field	Value
Publication number	US-10365231-B2
Application number	US-201815866768-A
Country	US
Kind code	B2
Filing date	Jan 10, 2018
Priority date	Feb 21, 2013
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A method and system are presented for use in optical measurements on patterned structures. The method comprises performing a number of optical measurements on a structure with a measurement spot configured to provide detection of light reflected from an illuminating spot at least partially covering at least two different regions of the structure. The measurements include detection of light reflected from said at least part of the at least two different regions comprising interference of at least two complex electric fields reflected from said at least part of the at least two different regions, and being therefore indicative of a phase response of the structure, carrying information about properties of the structure.

First claim

The invention claimed is:

1. A method for use in optical measurements on patterned structures to determine parameters of a region of interest in the structure, the method comprising:
performing at least two optical measurements on the structure, wherein each of said at least two optical measurement comprises illuminating the region of interest with an illuminating spot of a size larger than said region of interest, detecting reflected light fields reflected from the illuminating spot, and generating measured data corresponding to the detected reflected light fields, said measured data being indicative of mixed contributions of reflected light fields from illuminated region of interest and from illuminated different region in surroundings of the region of interest, and wherein said at least two optical measurements are performed with at least one different measurement condition such that the at least two measured data are indicative of differently mixed contributions of the reflected light fields from the illuminated region of interest and the illuminated different region; and
processing the at least two measured data and extracting data indicative of the reflected light field from the illuminated region of interest, thereby enabling determination of the parameters of the region of interest.

2. The method according to claim 1 , wherein said region of interest and said different region in the surrounding of the region of interest are first and second patterned regions having different first and second patterns, respectively.

3. The method according to claim 1 , wherein one of said region of interest and said different region in the surrounding of the region of interest is a patterned region and the other of said region of interest and said different region is an unpatterned region.

4. The method according to claim 1 , wherein said region of interest is a patterned region.

5. The method according to claim 1 , wherein said number of the optical measurements are performed with at least one normal and oblique incidence modes.

6. The method according to claim 1 , wherein said at least one different measurement condition comprise illumination with different wavelengths.

7. The method according to claim 1 , wherein each of said optical measurements are performed with multiple wavelengths, the detected light being therefore indicative of a spectral response of the structure.

8. The method according to claim 1 , wherein said processing of the at least two measured data utilizes data indicative of mixing coefficients.

9. The method according to claim 8 , wherein the mixing coefficients are determined from preliminary measurements on the structure.

10. The method according to claim 8 , wherein said at least two optical measurements comprise optical measurements performed with shifted positions of the illuminating spot, thereby controllably modifying values of the mixing coefficients affecting the detected reflected light fields, and increasing amount of information about parameters of the region of interest.

11. A system for use in measurements on patterned structures to determine parameters of a region of interest in the structure, the system comprising:
an optical measurement device comprising:
an illumination unit configured and operable for focusing light onto the structure with an illuminating spot of a size larger than a region of interest being measured to thereby cause light reflections from illuminated region of interest under measurements and illuminated different region in surrounding of said region of interest; and
a light detection unit collecting light including the light reflections from the illuminated region of interest and the illuminated different region in surrounding of the region of interest, and generating measured data corresponding to the collected light, the measured data being therefore indicative of mixed contributions of the reflected light from the illuminated patterned region and from the illuminated different region in surrounding of the region of interest; and

a control unit configured for data communication with the measurement device, said control unit being configured and operable to process at least two measured data corresponding to at least two optical measurements differing in at least one measurement condition and extract data indicative of the reflected light from the illuminated region of interest, to thereby enable determination of the parameters of the region of interest.

12. The system according to claim 11 , wherein the optical measurement device is configured to perform optical measurements with at least one normal and oblique incidence modes.

13. The system according to claim 11 , wherein the optical measurement device is configured and operable to perform optical measurements using illumination with different wavelengths.

14. The system according to claim 11 , wherein the optical measurement device is configured and operable to perform two or more optical measurements, each with multiple wavelengths, the detected light being therefore indicative of a spectral response of the structure.

15. The system according to claim 11 , wherein the control unit is configured to perform said processing of the at least two measured data utilizing data indicative of mixing coefficients.

16. The system according to claim 15 , wherein the control unit is configured to access stored data about the mixing coefficients determined from preliminary measurements on the structure.

17. The system according to claim 15 , wherein the optical measurement device is configured and operable to perform optical measurements with shifted positions of the illuminating spot, thereby controllably modifying values of the mixing coefficients affecting the detected reflected light fields, and increasing amount of information about parameters of the region of interest.

Assignees

• Nova Measuring Instr Ltd

Inventors

• Barak Gilad
• Shafir Dror
• Hainick Yanir
• Gov Shahar

Classifications

• G03F7/70625

  Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness · CPC title

• G01N21/956 Primary

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• G01B2210/56

  Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth · CPC title

• G03F7/70616

  Monitoring the printed patterns · CPC title

• G01N21/9501

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title