US 2022/0034652 A1Published application

Grey-mode scanning scatterometry overlay metrology

AssigneeKLA Corporation

InventorsAmnon Manassen, Andrew V. Hill

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Abstract

An overlay metrology system may include, an illumination sub-system, a collection sub-system and a controller. The illumination sub-system may include one or more illumination optics configured to direct an illumination beam to an overlay target on a sample as the sample is scanned along a stage-scan direction by a translation stage, where the overlay target includes one or more cells having a grating-over-grating structure with periodicity along the stage-scan direction. The collection sub-system may include an objective lens, a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction and +1-order diffraction, and a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction and −1-order diffraction. The controller may receive time-varying interference signals from the first and second photodetectors and determine an overlay error between the first and second layers of the sample along the stage-scan direction.

Claims24

Dependent claims

An overlay metrology system comprising:

an illumination sub-system comprising:
an illumination source configured to generate an illumination beam;
one or more illumination optics configured to direct the illumination beam to an overlay target on a sample as the sample is scanned along a stage-scan direction by a translation stage, wherein the overlay target includes one or more cells having a grating-over-grating structure with periodicity along the stage-scan direction, wherein the grating-over-grating structures include first-layer grating features on a first layer of the sample and second-layer grating features on a second layer of the sample in an overlapping region;
a collection sub-system comprising:
an objective lens;
a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and +1-order diffraction from the overlay target;
and
a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and −1-order diffraction from the overlay target;
and
a controller communicatively coupled to the first and second photodetectors, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive time-varying interference signals from the first and second photodetectors as the overlay target is scanned along the stage-scan direction;
and
determine an overlay error between the first and second layers of the sample along the stage-scan direction based on the time-varying interference signals.

10 more elements

An overlay metrology system comprising:

an illumination sub-system comprising:
a first illumination channel and a second illumination channel for illuminating an overlay target on a sample with a first illumination beam and a second illumination beam as the sample is scanned along a stage-scan direction by a translation stage, wherein the overlay target includes one or more first cells having a grating-over-grating structure with periodicity along a first direction and one or more second cells having a grating-over-grating structure with periodicity along a second direction orthogonal to the first direction, wherein the stage-scan direction is angled with respect to the first direction and the second direction, wherein a particular grating-over-grating structure includes first-layer grating features on a first layer of the sample and second-layer grating features on a second layer of the sample in an overlapping region, wherein the first and second illumination channels illuminate different cells of the overlay target separated along a direction orthogonal to the stage-scan direction;
a collection sub-system comprising:
an objective lens;
a first detection channel and a second detection channel associated with the first illumination channel and the second illumination channel, respectively, wherein a particular detection channel comprises:
a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and +1-order diffraction from the overlay target;
and
a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and −1-order diffraction from the overlay target;
and
a controller communicatively coupled to the first and second photodetectors, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive time-varying interference signals from the first and second photodetectors of each of the first and second detection channels as the overlay target is scanned along the measurement direction;
and
determine an overlay error between the first and second layers of the sample along the first and second directions based on the time-varying interference signals.

10 more elements

An overlay metrology system comprising:

an illumination sub-system comprising:
an illumination source configured to generate an illumination beam;
and
a scan mirror configured to scan the illumination beam along a beam-scan direction across an overlay target on a sample as the sample is translated along a stage-scan direction orthogonal to the beam-scan direction by a translation stage, wherein the overlay target includes one or more cells having a grating-over-grating structure with periodicity along a measurement direction, wherein the measurement direction corresponds to the beam-scan direction or the stage-scan direction, wherein the grating-over-grating structures include first-layer grating features on a first layer of the sample and second-layer grating features on a second layer of the sample in an overlapping region;
a collection sub-system comprising:
an objective lens;
a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and +1-order diffraction from the overlay target;
and
a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and −1-order diffraction from the overlay target;
and
a controller communicatively coupled to the first and second photodetectors, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive time-varying interference signals from the first and second photodetectors as the overlay target is scanned along the measurement direction;
and
determine an overlay error between the first and second layers of the sample along the measurement direction based on the time-varying interference signals.

11 more elements

An overlay metrology system comprising:

an illumination sub-system comprising:
a first illumination channel and a second illumination channel for illuminating an overlay target on a sample with a first illumination beam and a second illumination beam as the sample is scanned along a stage-scan direction by a translation stage with a first illumination beam and a second illumination beam, respectively, wherein the overlay target includes one or more first cells having a grating-over-grating structure with periodicity along a first direction and one or more second cells having a grating-over-grating structure with periodicity along a second direction orthogonal to the first direction, wherein the stage-scan direction corresponds to the first direction or the second direction, wherein a particular grating-over-grating structure includes first-layer grating features on a first layer of the sample and second-layer grating features on a second layer of the sample in an overlapping region, wherein the first and second illumination channels illuminate different cells of the overlay target separated along a direction orthogonal to the stage-scan direction;
and
one or more beam-scanners to scan the first and second illumination beams along a beam-scan direction orthogonal to the stage-scan direction while the sample is scanned along the stage-scan direction;
and
a collection sub-system comprising:
an objective lens;
and
a first detection channel and a second detection channel associated with the first illumination channel and the second illumination channel, respectively, wherein a particular detection channel comprises:
a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and +1-order diffraction from the overlay target;
and
a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction from the overlay target and −1-order diffraction from the overlay target;
and
a controller communicatively coupled to the first and second photodetectors, the controller including one or more processors configured to execute program instructions causing the one or more processors to:
receive time-varying interference signals from the first and second photodetectors of each of the first and second detection channels as the overlay target is scanned along the measurement direction;
and
determine an overlay error between the first and second layers of the sample along the first and second directions based on the time-varying interference signals.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/178,089Filed 17 Feb 2021
Priority: 3 Aug 2020
Published: 3 Feb 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G01B 11/272
For testing the alignment of axes: using photoelectric detection means
G03F 7/70633
Monitoring the printed patterns: overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the…
G01B 9/02027
Characterised by the beam path configuration: two or more interferometric channels or interferometers
G01B 9/02043
Characterised by particular imaging or detection techniques: imaging of the Fourier or pupil or back focal plane, i.e. angle resolved imaging

Family

Application63/060,576Us provisional application · filed 3 Aug 2020
Application63/144,205Us provisional application · filed 1 Feb 2021
US 11,300,405 B2Related patent
US 2022/0034652 A1This patent

From the US filing history. Foreign family members aren’t listed.

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