Methods and devices for reducing errors in Goos-Hänchen corrections of displacement data

Patent metadata

Field	Value
Publication number	US-9335159-B2
Application number	US-201414462910-A
Country	US
Kind code	B2
Filing date	Aug 19, 2014
Priority date	May 2, 2012
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

An exemplary method involves, in a system comprising a tool that performs a task on a workpiece, a method for determining displacement of the workpiece relative to the tool. Respective displacements of loci of at least a region of the workpiece are mapped using a Goos-Hänchen-insensitive (GH-insensitive) displacement sensor to produce a first set of physical displacement data for the region. Also mapped are respective displacements, from the tool, of the loci using a GH sensitive sensor to produce a second set of optical displacement data for the region. Goodness of fit (GOF) is determined of the second set of data with the first set. According to the GOF, respective GH-correction (GHC) coefficients are determined for at least one locus of the region. When measuring displacement of the at least one locus in the region relative to the tool, the respective GHC coefficient is applied to the measured displacement to reduce an error that otherwise would be present in the measured displacement due to a GH effect.

First claim

What is claimed is:

1. In a system comprising a tool that performs a task on a workpiece, a method for determining displacement of the workpiece relative to the tool, comprising:
from Goos-Hänchen (GH) insensitive focus information, mapping respective displacements of loci of at least a region of the workpiece to produce a first set of displacement data for the region;
mapping respective displacements, from the tool, of the loci using an optical displacement sensor to produce a second set of displacement data for the region;
determining goodness of fit of the second set with the first set;
according to the goodness of fit, determining a respective Goos-Hänchen correction (GHC) coefficient for at least one locus of the region; and
when measuring displacement of the at least one locus in the region relative to the tool, applying the respective GHC coefficient to the measured displacement to reduce an error that otherwise would be present in the measured displacement due to a GH effect.

2. The method of claim 1 , wherein the first set of displacement data comprises data produced by at least one physical displacement sensor.

3. The method of claim 1 , wherein the first set of displacement data comprises displacement data obtained from a focus map of the region.

4. The method of claim 1 , wherein the first set of displacement data comprises true focus position data.

5. The method of claim 1 , wherein the first set of displacement data is mapped before mapping the second set of displacement data.

6. The method of claim 5 , wherein the first set of displacement data is mapped during development of a process to be performed on the workpiece by the tool.

7. The method of claim 1 , wherein the respective displacements of the loci are measured using the optical displacement sensor on a real-time basis.

8. A method for determining displacement of an object, comprising:
using at least one optical sensor responsive to a light beam reflected from a region on a surface of an object, determining respective displacements of one or more loci in the region to produce an optical displacement map of the region;
using at least one Goos-Hänchen (GH) insensitive sensor, determining respective displacements of the one or more loci in the region to produce a physical displacement map of the region;
fitting data of the optical displacement map to corresponding data of the physical displacement map;
according to a goodness of fit of data of the optical displacement map to data of the physical displacement map, determining corresponding Goos-Hänchen correction (GHC) coefficients corresponding to the data of at least the loci;
to a subsequent measurement of displacement of a locus of the region using at least one optical sensor, applying corresponding GHC coefficients to produce a measurement of substrate position in which GHC's are calibrated.

9. The method of claim 8 , wherein data in the physical displacement map are obtained using an air gauge.

10. The method of claim 8 , wherein data in the physical displacement map are obtained during a process-development time.

11. The method of claim 8 , wherein the GH-insensitive sensor comprises a physical-displacement sensor.

12. A method for determining displacement of an object, comprising:
using at least one Goos-Hänchen (GH) sensitive sensor responsive to a light beam reflected from a region on a surface of an object, determining respective displacements of one or more loci in the region to produce an optical map of the region;
using at least one GH-insensitive sensor, determining respective displacements of one or more loci in the region to produce a physical map of the region;
assessing goodness of fit of displacement data of the optical map with displacement data of the physical map;
according to the goodness of fit, determining from the displacement data a corresponding set of Goos-Hänchen correction (GHC) coefficients;
using the at least one GH-sensitive sensor, obtaining a subsequent measurement of displacement of a location, within the region, of the object; and
applying at least one GHC coefficient from the set to the subsequent measurement of displacement to produce a measurement of substrate position including a calibrated GHC.

13. The method of claim 12 , wherein:
the at least one GH-sensitive sensor comprises at least one optical sensor; and
the at least one GH-insensitive sensor comprises at least one physical sensor.

14. A system for determining displacement of a workpiece relative to a tool that performs a task on a workpiece, comprising:
a Goos-Hänchen (GH)-insensitive sensor configured to map displacements of loci of at least a region of the workpiece to produce a first set of displacement data comprising respective displacements of loci of at least a region of the workpiece;
an optical displacement sensor configured to map displacements, from the tool, of the loci to produce a second set of displacement data for the region;
a controller configured to:
determine goodness of fit of the second set with the first set,
determine, according to the goodness of fit, a respective Goos-Hänchen correction (GHC) coefficient for at least one locus of the region; and
apply the respective GHC coefficient to the measured displacement when measuring displacement of the at least one locus in the region relative to the tool, to reduce an error that otherwise would he present in the measured displacement due to a GH effect.

15. The system of claim 14 , wherein the GH-insensitive sensor includes at least one physical displacement sensor, and further wherein the first set of displacement data comprises data produced by the at least one physical displacement sensor.

16. The system of claim 14 , wherein the first set of displacement data comprises displacement data obtained from a focus map of the region.

17. The system of claim 14 , wherein the first set of displacement data comprises true focus position data.

18. The system of claim 14 , wherein the GH-insensitive sensor is configured to map said first set of displacement data before said second set of displacement data is mapped.

19. The system of claim 18 , wherein the GH-insensitive sensor is configured to map said first set of displacement data during development of a process to be performed on the workpiece by the tool.

20. The system of claim 14 , wherein the optical displacement sensor is configured to measure the respective displacements of the loci on a real-time basis.

21. A system for determining displacement of an object, comprising:
at least one optical sensor responsive to a light beam reflected from a region on a surface of an object, and configured to determine respective displacements of one or more loci in the region to produce an optical displacement map of the region;
at least one Goos-Hänchen (GH) insensitive sensor, configured to determine respective displacements of the one or more loci in the region to produce a physical displacement map of the region;
a controller configured to:
fit data of the optical displacement map to corresponding data of the physical displacement map;
determine, according to a goodness of fit of data of the optical displacement map to data of the physical displacement map, corresponding Goos-Hänchen correction (GHC) coefficients corresponding to the data of at least the loci; and p 2 apply corresponding GHC coefficients to a subsequent measurement of displacement of a locus of the region using at least one optical sensor to produce a measurement of subst

Assignees

• Nikon Corp

Inventors

• Sogard Michael
• Smith Daniel G
• Williamson David M

Classifications

• G03F7/00

  Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor (using photoresist structures for special production processes, see the relevant places, e.g. B44C, H10P76/00, H05K) · CPC title

• G01B11/14 Primary

  for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) · CPC title

• G01B11/026

  by measuring distance between sensor and object (G01B11/0608 takes precedence) · CPC title

• G01B21/045 Primary

  Correction of measurements (G01B9/02055 takes precedence) · CPC title