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 Title: |
US5798947:
Methods, apparatus and computer program products for self-calibrating two-dimensional metrology stages
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Ye, Jun; Palo Alto, CA
Pease, Roger Fabian Wedgwood; Arlington, VA
Takac, Michael T.; San Jose, CA
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| Assignee: |
The Board of Trustees of the Leland Stanford, Jr. University, Stanford, CA
International Business Machines Corp., Armonk, NY
other patents from STANFORD UNIVERSITY (675809) (approx. 1,667)
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| Published / Filed: |
1998-08-25
/ 1997-03-03
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| Application Number: |
US1997000810537
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| IPC Code: |
Advanced:
G01B 21/04;
G03F 7/20;
Core:
G01B 21/02;
more...
IPC-7:
G01B 7/00;
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| ECLA Code: |
G03F7/20T22; G01B21/04B; G03F7/20T24;
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| U.S. Class: |
Current:
702/095;
702/153;
977/839;
977/849;
977/880;
Original:
361/589;
364/560;
364/571.01;
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| Field of Search: |
364/167.01,474.35,474.34,559,560,571.01-571.08
356/401,399,400,375,356,138-139.04,388,395-398
073/1.75,1.79
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| Priority Number: |
| 1997-03-03 |
US1997000810537 |
| 1996-09-25 |
US1996000718922 |
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| Abstract: |
Methods, apparatus and computer program products for selfcalibrating two-dimensional metrology stages include using a rigid artifact plate having an NxN array of marks thereon to map each of a two-dimensional array of stage positions (u,v) to a corresponding position in a Cartesian coordinate grid (x,y) to determine the distortion functions Gx(x,y) and Gy(x,y). This mapping function is performed by a series of operations which preferably use an orthogonal Fourier series to decouple determination of a pivoting point and a rotation angle from determination of the distortion functions. These operations include, among other things, determining complete and incomplete non-four-fold rotationally symmetric distortion between the two-dimensional array of stage positions (u,v) and the Cartesian coordinate grid (x,y). Operations are then performed to decouple the determination of the pivoting point and the rotation angle from the determination of the distortion functions Gx(x,y) and Gy(x,y) by determining (i) a two-dimensional translation misalignment error and a rotation misalignment error from the complete and incomplete non-four-fold rotationally symmetric distortion and then determining (ii) complete four-fold rotationally symmetric distortion between the two-dimensional array of stage positions and the Cartesian coordinate grid from, among other things, the two-dimensional translation misalignment error and the rotation misalignment error. These operations provide a highly efficient method of self-calibrating metrology and lithography stages.
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| Attorney, Agent or Firm: |
Myers Bigel Sibley & Sajovec ;
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| Primary / Asst. Examiners: |
Trammell, James P.;
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| INPADOC Legal Status: |
Show legal status actions
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| Parent Case: |
This application is a continuation of Ser. No. 08/718,922 filed Sep. 25, 1996, abandoned.
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| Family: |
None
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First Claim:
Show all 47 claims |
That which is claimed is:
1. A method of calibrating a two-dimensional metrology stage by mapping each of a two-dimensional array of stage positions to a corresponding position in a Cartesian coordinate grid to determine distortion therebetween, comprising the steps of:
- providing on the stage a rigid artifact plate having a two-dimensional array of marks thereon at spaced intervals which form an (x,y) grid;
- measuring the location of each of the marks on the artifact plate while the artifact plate is maintained in an origin reference location on the stage;
- rotating the artifact plate relative to the origin reference location to dispose the artifact plate in a rotated reference location;
- measuring the location of each of the marks on the artifact plate while the artifact plate is maintained in the rotated reference location;
- determining complete non-four-fold rotationally symmetric distortion between the two-dimensional array of stage positions and the Cartesian coordinate grid, from the measured locations of the marks in the origin and rotated reference locations;
- translating the artifact plate at least one interval relative to the origin reference location to dispose the artifact plate in a translated reference location;
- measuring the location of each of a plurality of the marks on the artifact plate while the artifact plate is maintained in the translated reference location;
- determining incomplete non-four-fold rotationally symmetric distortion between the two-dimensional array of stage positions and the Cartesian coordinate grid, from the measured locations of the marks in the origin and translated reference locations;
- determining a two-dimensional translation misalignment error and a rotation misalignment error from the complete non-four-fold rotationally symmetric distortion and the incomplete non-four-fold rotationally symmetric distortion; and
- determining complete four-fold rotationally symmetric distortion between the two-dimensional array of stage positions and the Cartesian coordinate grid from the translation and rotation misalignment errors and the measured locations of the marks in the origin, rotated and translated reference locations.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 16 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other References: |
Takac et al., Self-Calibration In Two Dimensions: The Experiment, SPIE Proceedings on "Metrology, Inspection and Process Control for Microlithography X", Santa Clara, California, vol. 2725, Mar. 11-13, 1996, pp. 130-146.
Raugh, Absolute Two-Dimensional Sub-Micron Metrology For Electron Beam Lithography, Precision Engineering, 1985, Butterworth & Co (Publishers) Ltd., pp. 3-13.
(11 pages)
Cited by 2 patents
Kuniyoshi et al., Stepper Stability Improvement By A Perfect Self-Calibration System, SPIE vol. 2197, pp. 990-996.
Lawson et al., Calibration Algorithms For An Electron Beam Metrology System, Microelectronic Engineering 1 (1983), pp. 41-50.
Takac, Self-Calibration In One Dimension, SPIE vol. 2087, Photomask Technology and Management (1993), pp. 80-86.
Raugh, Absolute 2-D Sub-Micron Metrology For Electron Beam Lithography, SPIE vol. 480, Intgrated Circuit Metrology II (1984), pp. 145163.
Jun Ye, Errors in High-Precision Mask Making and Metrology, Solid State Electronics Laboratory, Semiconductor Research Corporation Contract No. MC-515, Mar. 1996, pp. 1-167.
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