Back to results
US 8,786,825 B2Granted
Apparatus and method of measuring a property of a substrate
AssigneeASML Netherlands B.V.
InventorsMarcus Adrianus Van De Kerkhof, Maurits Van Der Schaar, Andreas Fuchs, Martyn John Coogans
Life of this patent
Estimating the term…
Abstract
The present invention makes the use of measurement of a diffraction spectrum in or near an image plane in order to determine a property of an exposed substrate. In particular, the positive and negative first diffraction orders are separated or diverged, detected and their intensity measured to determine overlay (or other properties) of exposed layers on the substrate.
Claims25
An inspection apparatus configured to determine a property of a substrate, comprising:
- a radiation source configured to output a radiation beam toward an overlay target on a surface of the substrate;
- a collimator configured to collimate and focus the radiation beam once reflected from the overlay target, and to separate diffraction orders of a diffraction spectrum of the reflected radiation beam;
- a detector configured to detect at least a subset of the separated diffraction orders of the reflected radiation beam and to determine first and second properties of respective first and second portions of the subset;
- and
- a processor configured to:
- determine the property of the substrate by comparing the first and second properties in a plane positioned in a range from where the radiation beam is converging toward an image plane of the collimator to where the radiation beam is diverging from the image plane;
- determine a position of the overlay target with respect to an optical axis of the collimator;
- and
- remove an error of relative positioning from the determination of the property of the substrate based on the determined position of the overlay target.
6 more elements
A scatterometer configured to determine a property of a substrate, comprising:
- a radiation source configured to output a radiation beam toward an overlay target on a surface of the substrate;
- a collimator configured to collimate and focus the radiation beam once reflected from the overlay target, and to separate diffraction orders of an angle-resolved spectrum of the reflected radiation beam;
- and
- a detector configured to detect the angle-resolved spectrum of the reflected radiation beam and to determine first and second properties of the angle-resolved spectrum, the detector being situated in a plane positioned in a range from where the radiation beam is converging toward an image plane of the collimator to where the radiation beam is diverging from the image plane;
- and
- a processor configured to:
- determine the property of the substrate by comparing the first and second properties of the angle-resolved spectrum;
- determine a position of the overlay target with respect to an optical axis of the collimator;
- and
- remove an error of relative positioning from the determination of the property of the substrate based on the determined position of the overlay target.
7 more elements
A method of measuring a property of a substrate, comprising:
- irradiating a target on a substrate with a radiation beam, the radiation beam being reflected from the target as a reflected radiation beam;
- collimating and focusing the reflected radiation beam using a collimator;
- diverging first diffraction orders of the reflected radiation beam;
- detecting the intensity of the first diffraction orders in a plane positioned within a range from where the reflected radiation beam is converging toward an image plane of the collimator to where the reflected radiation beam is diverging from the image plane;
- comparing the intensity of each of the first diffraction orders against the other;
- determining, from the comparing of the intensity of the first diffraction orders, a property of the substrate;
- determining a position of the target with respect to an optical axis of the collimator;
- and
- removing an error of relative positioning from the determining of the property of the substrate based on the determining of the position of the target.
6 more elements
A lithographic apparatus comprising:
- an illumination system arranged to illuminate a pattern;
- a projection system arranged to project an image of the pattern onto a substrate;
- and
- an inspection apparatus configured to determine a property of the substrate, the inspection apparatus comprising:
- a radiation source configured to output a radiation beam toward an overlay target on a surface of the substrate;
- a collimator configured to collimate and focus the radiation beam once reflected from the overlay target, and to separate diffraction orders of a diffraction spectrum of the reflected radiation beam;
- a detector configured to detect at least a subset of the separated diffraction orders of the reflected radiation beam and to determine first and second properties of respective first and second portions of the subset;
- and
- a processor configured to:
- determine the property of the substrate by comparing the first and second properties in a plane positioned in a range from where the radiation beam is converging toward an image plane of the collimator to where the radiation beam is diverging from the image plane;
- determine a position of the overlay target with respect to an optical axis of the collimator;
- and
- remove an error of relative positioning from the determination of the property based on the determined position of the overlay target.
10 more elements
A lithographic cell comprising:
- a coater arranged to coat a substrate with a radiation sensitive layer;
- a lithographic apparatus arranged to expose images onto the radiation sensitive layer of the substrate coated by the coater;
- a developer arranged to develop images exposed by the lithographic apparatus;
- and
- an inspection apparatus configured to determine a property of the substrate, the inspection apparatus comprising:
- a radiation source configured to output a radiation beam toward an overlay target on a surface of the substrate;
- a collimator configured to collimate and focus the radiation beam once reflected from the overlay target, and to separate diffraction orders of a diffraction spectrum of the reflected radiation beam;
- a detector configured to detect at least a subset of the separated diffraction orders of the reflected radiation beam in a plane positioned in a range from where the radiation beam is converging toward an image plane of the collimator to where the radiation beam is diverging from the image plane;
- and
- a processor configured to:
- determine first and second properties of respective first and second portions of the subset, and the property of the substrate by comparing the first and second properties;
- determine a position of the overlay target with respect to an optical axis of the collimator;
- and
- remove an error of relative positioning from the determination of the property of the substrate based on the determined position of the overlay target.
11 more elements
A device manufacturing method comprising:
- forming a pattern on a substrate using a lithographic apparatus;
- and
- determining a value related to a parameter of the pattern formed by:
- irradiating a target on the substrate with a radiation beam, the radiation beam being reflected from the target as a reflected radiation beam;
- collimating and focusing the reflected radiation beam using a collimator;
- diverging first diffraction orders of the reflected radiation beam;
- detecting the intensity of the first diffraction orders in a plane positioned within a range from where the reflected radiation beam is converging toward an image plane of the collimator to where the reflected radiation beam is diverging from the image plane;
- comparing the intensity of each of the first diffraction orders against the other;
- determining, from the comparing of the intensity of the first diffraction orders, the value related to the parameter of the pattern;
- determining a position of the target with respect to an optical axis of the collimator;
- and
- removing an error of relative positioning from the determining of the value based on the determining of the position of the target.
9 more elements
Dependencies are inferred from the claim text.