Overlay control with non-zero offset prediction

Patent metadata

Field	Value
Publication number	US-10409171-B2
Application number	US-201815867485-A
Country	US
Kind code	B2
Filing date	Jan 10, 2018
Priority date	Jan 25, 2017
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A process control system may include a controller configured to receive after-development inspection (ADI) data after a lithography step for the current layer from an ADI tool, receive after etch inspection (AEI) overlay data after an exposure step of the current layer from an AEI tool, train a non-zero offset predictor with ADI data and AEI overlay data to predict a non-zero offset from input ADI data, generate values of the control parameters of the lithography tool using ADI data and non-zero offsets generated by the non-zero offset predictor, and provide the values of the control parameters to the lithography tool for fabricating the current layer on the at least one production sample.

First claim

What is claimed:

1. A process control system, comprising:
a controller configured to communicatively couple to a lithography tool fabricating a current layer to provide control parameters to maintain overlay error between the current layer and one or more previous layers within a selected specification, the controller including one or more processors configured to execute program instructions configured to cause the one or more processors to:
receive after-development inspection (ADI) data after a lithography step for the current layer from an ADI tool, the ADI data including ADI overlay data indicative of overlay errors between the current layer and the one or more previous layers, the ADI data further including ADI flag data indicative of process deviations during fabrication of the one or more previous layers;
receive after etch inspection (AEI) overlay data after an exposure step of the current layer from an AEI tool, the AEI overlay data indicative of overlay errors between the current layer and the one or more previous layers, wherein a non-zero offset corresponds to a difference between overlay error determined from ADI data and AEI overlay data;
train a non-zero offset predictor with ADI data and AEI overlay data from one or more training samples to predict a non-zero offset from ADI data;
generate values of the control parameters of the lithography tool fabricating the current layer of at least one production sample using ADI data from one or more previous production samples and non-zero offsets generated by the non-zero offset predictor based on the ADI data from the one or more previous production samples; and
provide the values of the control parameters to the lithography tool for fabricating the current layer on the at least one production sample.

2. The process control system of claim 1 , wherein the one or more processors are further configured to execute program instructions configured to cause the one or more processors to:
receive ADI flag data from one or more subsequent layers on at least one production sample in a previous lot, the one or more subsequent layers fabricated above the current layer in the previous lot; and
train the non-zero offset predictor with the ADI flag data from the one or more subsequent layers.

3. The process control system of claim 2 , wherein generating the values of the control parameters of the lithography tool further comprises:
generating the values of the control parameters of the lithography tool based at least in part on non-zero offsets generated by the non-zero offset predictor based on the ADI flag data from the one or more subsequent layers on the at least one production sample in the previous lot.

4. The process control system of claim 1 , wherein the ADI flag data of a metrology target is generated by analyzing one or more regions of interest of the metrology target based on a target metric.

5. The process control system of claim 4 , wherein the metrology target includes a periodic structure, wherein the target metric comprises:
decomposing at least one of the one or more regions into a periodic component, a linear component, and a noise component.

6. The process control system of claim 5 , wherein the target metric further comprises:
at least one of a strength of the periodic component, a ratio of the strength of the periodic component to a strength of the noise component.

7. The process control system of claim 4 , wherein the metrology target includes a periodic structure, wherein the target metric comprises:
a measure of the symmetry of the one or more regions of interest.

8. The process control system of claim 1 , wherein the ADI metrology tool has a higher throughput than the AEI metrology tool.

9. The process control system of claim 1 , wherein the AEI metrology tool has a higher resolution than the ADI metrology tool.

10. The process control system of claim 1 , wherein the ADI overlay data and the ADI flag data are generated using a composite metrology recipe.

11. The process control system of claim 10 , wherein the composite recipe includes a first set of sampling locations for measuring the ADI overlay data and a second set of sampling locations for measuring the ADI flag data.

12. The process control system of claim 11 , wherein the first set of sampling locations is larger than the second set of sampling locations.

13. The process control system of claim 1 , wherein the ADI overlay data and the ADI flag data are generated on different metrology targets.

14. The process control system of claim 1 , wherein the ADI overlay data and the ADI flag data are generated on different cells of common metrology targets.

15. The process control system of claim 1 , wherein the ADI tool comprises:
an optical metrology tool.

16. The process control system of claim 1 , wherein the AEI tool comprises:
a particle-beam metrology tool.

17. The process control system of claim 16 , wherein the particle-beam metrology tool comprises:
at least one of an electron beam metrology tool or an ion-beam metrology tool.

18. A process control system, comprising:
a controller configured to communicatively couple to a lithography tool fabricating a current layer to provide control parameters to maintain overlay error between the current layer and one or more previous layers within a selected specification, the controller including one or more processors configured to execute program instructions configured to cause the one or more processors to:
receive after-development inspection (ADI) data after a lithography step for the current layer from an ADI tool, the ADI data including ADI overlay data indicative of overlay errors between the current layer and the one or more previous layers, the ADI data further including ADI flag data indicative of process deviations during fabrication of the one or more previous layers;
receive after etch inspection (AEI) overlay data after an exposure step of the current layer from an AEI tool, the AEI overlay data indicative of overlay errors between the current layer and the one or more previous layers, wherein a non-zero offset corresponds to a difference between overlay error determined from ADI data and AEI overlay data;
generate values of the control parameters of the lithography tool fabricating the current layer of at least one production sample using ADI data and AEI data from one or more previous production samples; and
provide the values of the control parameters to the lithography tool for fabricating the current layer on the at least one production sample.

19. The process control system of claim 18 , wherein generating the values of the control parameters of the lithography tool fabricating the current layer of the at least one production sample using ADI data and AEI data from the one or more previous production samples comprises:
training a non-zero offset predictor with ADI data and AEI overlay data from one or more training samples to predict a non-zero offset from ADI data; and
generating the values of the control parameters based on ADI data from the one or more previous production samples and non-zero offsets generated by the non-zero offset predictor based on the ADI data from the one or more previous production samples.

20. The process control system of claim 18 , wherein generating the values of the control parameters of the lithography tool fabricating the current layer of the at least one production sample using ADI data and AEI overlay data from the one or more previous production samples comprises:
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Assignees

• Kla Tencor Corp

Inventors

• Adel Michael E
• Manassen Amnon
• Pierson William
• Levy Ady
• Subrahmanyan Pradeep
• Yerushalmi Liran
• Choi Dongsub
• Heo Hoyoung
• Alumot Dror
• Robinson John Charles

Classifications

• G03F7/705

  Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions · CPC title

• G03F7/70508

  Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus · CPC title

• G03F7/7085

  Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load · 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

• G03F7/706837

  Data analysis, e.g. filtering, weighting, flyer removal, fingerprints or root cause analysis · CPC title