Inspection apparatus for lithography

• US 8,724,087 B2
• Filed: 04/08/2009
• Issued: 05/13/2014
• Est. Priority Date: 04/15/2008
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Van De Kerkhof, Marcus Adrianus, Kiers, Antoine Gaston Marie, Van Der Schaar, Maurits, Verstappen, Leonardus Henricus Marie, Middlebrooks, Scott Anderson, Fuchs, Andreas
• Primary Examiner(s): Gordon, Steven H Whitesell
• Assistant Examiner(s): Asfaw, Mesfin T
• Application Number:
  US12/933,481
• Publication Number:
  US 20110141444A1
• Time in Patent Office: 1,861 Days
• Field of Search: 355/53, 355/67, 355/77, 356/369, 356/401, 356/446
• US Class Current: 355/67
• CPC Class Codes: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 takes precedence
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G03F 7/70616 Monitoring the printed patterns

Abstract

A scatterometer configured to measure a property of a substrate, includes a radiation source configured to provide a radiation beam; and a detector configured to detect a spectrum of the radiation beam reflected from a target (30) on the surface of the substrate (W) and to produce a measurement signal representative of the spectrum. The apparatus includes a beam shaper (51, 53) interposed in the radiation path between the radiation source and the detector, the beam shaper being configured to adjust the cross section of the beam dependent on the shape and/or size of the target.

Claims

1. A scatterometer configured to measure a property of a substrate, comprising:

a radiation source configured to provide a radiation beam;

a detector;

a beam shaper interposed in a radiation path between the radiation source and the detector, the beam shaper being configured to adjust a cross section of the radiation beam based on a configuration of a target on a surface of the substrate and to output an adjusted radiation beam; and

a controller configured to measure a misalignment between the adjusted radiation beam and the target and to compensate for the measured misalignment,

wherein the detector is configured to detect a spectrum of the adjusted radiation beam reflected from the target and to produce a measurement signal representative of the spectrum.

2. The scatterometer according to claim 1, wherein the controller is configured to control a signal adjuster, the signal adjuster being configured to adjust the measurement signal to compensate for the measured misalignment.

3. The scatterometer according to claim 1, wherein the controller is configured to control a position adjuster, the position adjuster configured to adjust relative positions of the radiation beam and the target in order to optimize the measurement signal.

4. The scatterometer according to claim 1, wherein the beam shaper is interposed in a radiation path between the radiation source and the substrate.

5. The scatterometer according to claim 1, wherein the beam shaper is interposed in a radiation path between the substrate and the detector.

6. The scatterometer according to claim 1, wherein the beam shaper is configured to adjust the cross section of the radiation beam based on at least one of a shape of the target and a size of the target.

7. The scatterometer according to claim 1, wherein the beam shaper includes an aperture configured to selectively transmit a portion of the radiation beam as the adjusted radiation beam.

8. The scatterometer according to claim 1, wherein the beam shaper is configured such that the adjusted radiation beam is a variable cross section beam.

9. The scatterometer according to claim 1, wherein the beam shaper comprises an adjustable zoom lens.

10. The scatterometer according to claim 1, wherein the radiation source and the beam shaper are configured such that the target and another target on the substrate are illuminated substantially simultaneously.

11. The scatterometer according to claim 1, wherein the controller is configured to measure a reflection of the adjusted radiation beam from an edge of grating (EoG) portion of the target to measure the misalignment.

12. The scatterometer according to claim 1, further comprising a second beam shaper, wherein the controller is configured to control a second beam shaper to compensate for the measured misalignment.

13. The scatterometer according to claim 1, wherein the second beam shaper comprises a variable aperture.

14. A scatterometer configured to measure a property of a substrate, comprising:

a radiation source configured to provide a radiation beam;

a detector configured to detect a spectrum of the radiation beam reflected from a target on a surface of the substrate and to produce a measurement signal representative of the spectrum;

a beam shaper interposed in the radiation path between the substrate and the detector, the beam shaper being configured to trim the reflected radiation beam after reflection from the target; and

a controller configured to measure a misalignment between the radiation beam and the target and to compensate for the measured misalignment.

15. A method of measuring a property of a substrate, comprising:

generating a radiation beam;

detecting a spectrum of the radiation beam reflected from a target on the surface of the substrate;

producing a measurement signal representative of the spectrum;

shaping the radiation beam, prior to the detecting, to adjust a cross section of the radiation beam based on the configuration of the target;

measuring a misalignment between the shaped radiation beam and the target; and

compensating for the measured misalignment.

16. A method of measuring a property of a substrate, comprising:

generating a radiation beam;

detecting a spectrum of the radiation beam reflected from a target on a surface of the substrate;

producing a measurement signal representative of the spectrum;

trimming the reflected radiation after reflection from the target;

measuring a misalignment between the radiation beam and the target; and

compensating for the measured misalignment.

17. A lithographic apparatus comprising:

an illumination system arranged to illuminate a pattern;

a projection system arranged to project an image of the pattern on to a substrate; and

a scatterometer configured to measure a property of the substrate, the scatterometer, comprising;

a radiation source configured to provide a radiation beam;

a detector;

a beam shaper interposed in a radiation path between the radiation source and the detector, the beam shaper being configured to adjust a cross section of the radiation beam based on a configuration of a target on a surface of the substrate and to output an adjusted radiation beam wherein the detector is configured to detect a spectrum of the adjusted radiation beam reflected from the target and to produce a measurement signal representative of the spectrum; and

a controller configured to measure a misalignment between the adjusted radiation beam and the target and to compensate for the measured misalignment.

18. A lithographic cell comprising:

a coater arranged to coat a substrate with a radiation sensitive layer;

a lithographic apparatus arranged to expose an image onto the radiation sensitive layer of the substrate coated by the coater;

a developer arranged to develop the image exposed by the lithographic apparatus; and

a scatterometer configured to measure a property of the substrate, the scatterometer, comprising;

a radiation source configured to provide a radiation beam;

a detector;

a beam shaper interposed in a radiation path between the radiation source and the detector, the beam shaper being configured to adjust a cross section of the radiation beam based on a configuration of a target on a surface of the substrate and to output an adjusted radiation beam, wherein the detector is configured to detect a spectrum of the adjusted radiation beam reflected from the target and to produce a measurement signal representative of the spectrum; and

a controller configured to measure a misalignment between the radiation beam and the target and to compensate for the measured misalignment.

19. A device manufacturing method comprising:

forming a pattern on a substrate; and

determining a value related to a parameter of the pattern, the determining including;

generating a radiation beam;

detecting a spectrum of the radiation beam reflected from a target on a surface of the substrate and producing a measurement signal representative of the spectrum;

shaping the radiation beam, prior to the detecting, to adjust a cross section of the radiation beam dependent on the configuration of the target;

measuring, a misalignment between the shaped radiation beam and the target; and

compensating for the measured misalignment.