Adjustment of a metrology apparatus or a measurement thereby based on a characteristic of a target measured

Patent metadata

Field	Value
Publication number	US-2018364591-A1
Application number	US-201616061209-A
Country	US
Kind code	A1
Filing date	Nov 29, 2016
Priority date	Dec 17, 2015
Publication date	Dec 20, 2018
Grant date	—

Abstract

A method of adjusting a metrology apparatus, the method including: spatially dividing an intensity distribution of a pupil plane of the metrology apparatus into a plurality of pixels; and reducing an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjusting intensities of the plurality of pixels.

First claim

1 . A method of adjusting a metrology apparatus, the method comprising:
spatially dividing an intensity distribution of a pupil plane of the metrology apparatus into a plurality of pixels; and reducing an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjusting, using a hardware computer, intensities of the plurality of pixels.

2 . The method of claim 1 , wherein the pupil plane is an illumination pupil or a detection pupil.

3 . The method of claim 1 , wherein the measurement measures overlay, focus, aberration or a combination selected therefrom.

4 . The method of claim 1 , wherein the structural asymmetry comprises one or more selected from: a difference in side wall angle (SWA), floor tilt, and/or etch depth.

5 . The method of claim 1 , wherein adjusting the intensities comprises computing a cost function that represents the effect and that is a function of the intensities.

6 . The method of claim 5 , wherein adjusting the intensities further comprises finding values of the intensities that locally or globally minimizes or maximizes the cost function, or wherein the cost function is constrained.

7 . The method of claim 1 , further comprising:
identifying one or more pixels from the plurality of pixels, wherein the one or more pixels do not contribute to a signal used by the metrology apparatus in the measurement or wherein the contribution of the one or more pixels to the signal is below a threshold, and adjusting the intensities at the one or more identified pixels.

8 . The method of claim 7 , wherein the measurement is an overlay measurement and the one or more pixels do not contribute to a diffraction order used in the overlay measurement.

9 . The method of claim 1 , wherein reducing the effect of the structural asymmetry further comprises adjusting polarization at the pixels, and/or comprises adjusting bandwidth at the pixels, and/or comprises adjusting wavelength at the pixels.

10 . A computer program product comprising a non-transitory computer-readable medium having instructions thereon, the instructions, when executed by a computer system, configured to cause the computer system to at least:
spatially divide an intensity distribution of a pupil plane of a metrology apparatus into a plurality of pixels; and reduce an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjustment of intensities of the plurality of pixels.

11 . The computer program product of claim 10 , wherein the pupil plane is an illumination pupil or a detection pupil.

12 . A method of adjusting a metrology apparatus, the method comprising:
setting or adjusting a parameter of the metrology apparatus or of a measurement by the metrology apparatus, to a value based on a characteristic of a target measured by the metrology apparatus.

13 . The method of claim 12 , wherein adjusting the parameter comprises computing a cost function that represents a quality of measurement of the target and is a function of the parameter.

14 . The method of claim 12 , comprising measuring the target with the metrology apparatus.

15 . A method comprising:
setting a characteristic of a target to a value based on which a parameter of a metrology apparatus or of a measurement by the metrology apparatus on the target is adjusted; and fabricating the target on a substrate.

16 . The method of claim 12 , wherein the measurement is one or more selected from: a measurement of overlay, a measurement of focus, and/or a measurement of aberration.

17 . The method of claim 12 , wherein the parameter is one or more selected from: an intensity at an illumination pupil of the metrology apparatus, a polarization at an illumination pupil of the metrology apparatus, a wavelength at an illumination pupil of the metrology apparatus, a bandwidth at an illumination pupil of the metrology apparatus, an intensity at a detection pupil of the metrology apparatus, a polarization at a detection pupil of the metrology apparatus, a wavelength at a detection pupil of the metrology apparatus, a bandwidth at a detection pupil of the metrology apparatus, a characteristic of projection optics of the metrology apparatus and/or a characteristic of a source of the metrology apparatus.

18 . The method of claim 12 , wherein setting or adjusting the parameter impacts a quality of the measurement, the quality comprising detectability of the target, accuracy of the measurement, and/or robustness of the measurement.

19 . The method of claim 12 , wherein the characteristic of the target comprises a location of the target on a substrate.

20 . A computer program product comprising a non-transitory computer-readable medium having instructions thereon, the instructions, when executed by a computer system, configured to cause the computer system to at least perform the method of claim 12 .

Assignees

• Asml Netherlands Bv

Inventors

• Socha Robert John
• Den Boef Arie Jeffrey
• Pandey Nitesh

Classifications

• G03F7/706

  Aberration measurement · CPC title

• G01N21/956

  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

• G03F7/70633 Primary

  Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching · CPC title

• G01B2210/56

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

• G03F7/70641 Primary

  Focus · CPC title