Calibration method, inspection method and apparatus, lithographic apparatus, and lithographic processing cell

Patent metadata

Field	Value
Publication number	US-9188875-B2
Application number	US-200913132011-A
Country	US
Kind code	B2
Filing date	Dec 1, 2009
Priority date	Dec 16, 2008
Publication date	Nov 17, 2015
Grant date	Nov 17, 2015

Abstract

Disclosed are methods, apparatuses, and lithographic systems for calibrating an inspection apparatus. Radiation is projected onto a pattern in a target position of a substrate. By making a plurality of measurements of the pattern and comparing the measured first or higher diffraction orders of radiation reflected from the pattern of different measurements, a residual error indicative of the error in a scatterometer may be calculated. This error is an error in measurements of substrate parameters caused by irregularities of the scatterometer. The residual error may manifest itself as an asymmetry in the diffraction spectra.

First claim

What is claimed is:

1. A method comprising:
measuring at least two measurements of a patterned target on a substrate, wherein the substrate defines an x-y plane and at least one of the at least two measurements is made using an inspection apparatus, and each measurement comprises:
projecting a beam of radiation onto the patterned target, and
measuring at least one diffraction order of radiation reflected from the patterned target,
wherein the at least two measurements are made at two different rotation orientations of the patterned target;

determining a first preliminary value of a parameter of the patterned target from the at least one of the at least two measurements;
determining a second preliminary value of the parameter of the patterned target from the other one of the at least two measurements, wherein the first and second preliminary values comprise components in the x- and y-direction; and
determining a residual error indicative of an error of the inspection apparatus including comparing the at least two measurements, wherein the residual error is a variation in intensity of the at least one diffraction order of radiation reflected from the patterned target caused by the error in the inspection apparatus, wherein the determining comprises using the x- and y-components from the first and second preliminary values of the parameter to calculate the residual error.

2. The method of claim 1 , wherein at least two of the at least two measurements of the patterned target are made using the inspection apparatus.

3. The method of claim 2 , wherein a first orientation of the patterned target with respect to the inspection apparatus for at least one of the at least two measurements is rotated by an angle D about a normal to a plane of the substrate compared to a second orientation of the patterned target for the other one of the at least two measurements.

4. The method of claim 3 , wherein the angle D is at least one of 90°, 180°, and 270°.

5. The method of claim 3 , wherein the at least two measurements of the patterned target are carried out at angles of 0°, 90°, 180°, or 270°.

6. The method of claim 3 , wherein:
the at least two measurements each give rise to a diffraction spectrum made up of pixels representing radiation intensity for a range of angles of incidence of the diffracted light on the patterned target; and
the diffraction spectra for the at least two measurements are aligned, such that a detected intensity for each angle of incidence in a first diffraction spectrum is compared with a detected intensity for each substantially same angle of incidence in a second diffraction spectrum.

7. The method of claim 6 , wherein the aligned diffraction spectra of the at least two measurements are compared, such that a difference between the at least two measurements represents a value for the residual error.

8. The method of claim 3 , wherein the at least one of the at least two measurements is repeated multiple times.

9. The method of claim 1 , wherein at least one of the at least two measurements is made using a reference inspection apparatus and at least another one of the at least two measurements is made using the inspection apparatus to be calibrated.

10. The method of claim 9 , wherein the determining the residual error of the inspection apparatus further comprises assuming that the reference inspection apparatus has substantially no error.

11. The method of claim 9 , wherein the reference inspection apparatus has a known error.

12. The method of claim 9 , wherein the at least one of the at least two measurements are repeated multiple times.

13. The method of claim 9 , wherein the residual error comprises a difference in error between the inspection apparatus and the reference inspection apparatus, and
wherein the determining the residual error further comprises comparing and finding a difference between the first preliminary value of the parameter measured using the inspection apparatus and a third preliminary value of the parameter measured using the reference inspection apparatus.

14. The method of claim 13 , wherein the parameter is a profile of a pattern in the patterned target.

15. The method of claim 13 , wherein the parameter is a critical dimension of a pattern on the patterned target.

16. The method of claim 1 , wherein the determining the residual error further comprises comparing a first diffraction order of the reflected radiation in the at least two measurements.

17. The method of claim 1 , wherein an illumination error is measured using a reference beam of the inspection apparatus and the illumination error is the error caused by asymmetry in components of the inspection apparatus in an optical path of the reference beam.

18. The method of claim 1 , wherein the residual error is a result of an asymmetry in the inspection apparatus.

19. The method of claim 18 , wherein the at least two measurements comprise measurements of asymmetry in measured diffraction spectra of the reflected radiation.

20. A method comprising:
calibrating an inspection apparatus using a method to obtain a residual error, wherein the method to obtain the residual error comprises:
measuring at least three two measurements of a patterned target on a substrate defining an x-y plane using the inspection apparatus comprising:
projecting a beam of radiation onto the patterned target; and
measuring at least one diffraction order of radiation reflected from the patterned target,
wherein the at least two measurements are two at two different rotation orientations of the patterned target,

determining a first preliminary value of a parameter of the patterned target from the at least one of the at least two measurements;
determining a second preliminary value of the parameter of the patterned target from the other one of the at least two measurements, wherein the first and second preliminary values comprise components in the x- and y-direction; and
determining a residual error indicative of an error of the inspection apparatus by comparing the at least two measurements, the residual error being a variation in intensity of at least one diffraction order of radiation reflected from the patterned target caused by the error in the inspection apparatus, wherein the determining comprises using the x- and y-components from the first and second preliminary values of the parameter to calculate the residual error;
correcting the measurement of a first or higher diffraction order based on the residual error; and
determining a parameter value of the patterned target from the corrected at least one diffraction order of radiation reflected from the patterned target.

21. The method of claim 20 , wherein the parameter is a profile of a structure in the patterned target.

22. The method of claim 20 , wherein the parameter is a critical dimension of a structure in the patterned target.

23. A method comprising:
measuring at least two measurements of diffraction spectra of radiation diffracted from a patterned target on a substrate defining an x-y plane using an inspection apparatus, each of the at least two measurements comprises:
projecting a beam of radiation onto the patterned target, and
measuring at least one diffraction order of radiation reflected from the patterned target, wherein the at least two measurements are made at two different rotation orientations of the patterned;

determining a first preliminary value of a parameter of the patterned target from the at

Assignees

• Cramer Hugo Augustinus Joseph
• Van Der Schaar Maurits
• Asml Netherlands Bv

Inventors

• Cramer Hugo Augustinus Joseph
• Van Der Schaar Maurits

Classifications

• G03F7/70616

  Monitoring the printed patterns · CPC title

• G03F7/70625

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

• G03F7/70516

  Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors · CPC title

• G01N21/4785

  Standardising light scatter apparatus; Standards therefor · 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