Aided image reconstruction

• US 10,621,718 B2
• Filed: 03/21/2019
• Issued: 04/14/2020
• Est. Priority Date: 03/23/2018
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Konecky, Soren, Danen, Robert
• Primary Examiner(s): Hung, Yubin
• Application Number:
  US16/361,079
• Publication Number:
  US 20190295237A1
• Time in Patent Office: 390 Days
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G01N 2223/401 image processing
• CPC Class Codes: G01N 23/2251 using incident electron beams, e.g. scanning electron microscopy [SEM]
• CPC Class Codes: G06F 18/22 Matching criteria, e.g. proximity measures
• CPC Class Codes: G06T 2207/10056 Microscopic image
• CPC Class Codes: G06T 2207/20224 Image subtraction
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 3/4053 based on super-resolution, i.e. the output image resolution being higher than the sensor resolution
• CPC Class Codes: G06T 7/0006 using a design-rule based approach
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/174 involving the use of two or more images
• CPC Class Codes: G06V 20/693 Acquisition

Abstract

Methods and systems for determining boundaries of patterned features formed on a specimen from an unresolved image of the specimen are provided. One system includes computer subsystem(s) configured for comparing a difference image in which patterned feature(s) are unresolved to different simulated images. The different simulated images are generated by simulating difference images generated for the patterned feature(s) formed on the specimen with different perturbations, respectively. The computer subsystem(s) are configured for, based on the comparing, assigning an amplitude to each of the different perturbations. The computer subsystem(s) are further configured for determining one or more boundaries of the patterned feature(s) formed on the specimen by applying the different perturbations to one or more designed boundaries of the patterned feature(s) with the assigned amplitudes.

Claims

1. A system configured to determine boundaries of one or more patterned features formed on a specimen from an unresolved image of the one or more patterned features on the specimen, comprising:

an inspection subsystem comprising at least an energy source and a detector, wherein the energy source is configured to generate energy that is directed to a specimen, wherein the detector is configured to detect energy from the specimen and to generate images responsive to the detected energy, and wherein one or more patterned features formed on the specimen are unresolved in the images generated by the detector; and

one or more computer subsystems configured for;

generating a difference image for the one or more patterned features by subtracting a reference image from one of the images generated by the detector for the one or more patterned features;

comparing the difference image to different simulated difference images, wherein the different simulated difference images are generated by simulating images generated for the one or more patterned features formed on the specimen with different perturbations, respectively;

based on results of the comparing, assigning an amplitude to each of the different perturbations; and

determining one or more boundaries of the one or more patterned features formed on the specimen by applying the different perturbations to one or more designed boundaries of the one or more patterned features with the assigned amplitudes.

2. The system of claim 1, wherein the one or more computer subsystems are further configured for detecting defects on the specimen based on the one or more determined boundaries.

3. The system of claim 1, wherein the one or more computer subsystems are further configured for detecting defects on the specimen based on the one or more determined boundaries and determining one or more sub-resolution features of the defects based on the one or more determined boundaries.

4. The system of claim 1, wherein the one or more computer subsystems are further configured for comparing the one or more determined boundaries and the one or more designed boundaries and determining if one or more differences between the one or more determined boundaries and the one or more designed boundaries are caused by one or more defects of interest, one or more nuisances, or noise.

5. The system of claim 1, wherein the different perturbations comprise deviations in the one or more designed boundaries of the one or more patterned features due to known defects of interest and known nuisances.

6. The system of claim 1, wherein the different perturbations comprise deviations in the one or more designed boundaries of the one or more patterned features at two or more different positions along the one or more boundaries.

7. The system of claim 1, wherein said comparing comprises finding a combination of the smallest number of the different simulated images that generates the closest approximation to the difference image.

8. The system of claim 7, wherein said comparing is performed with regularization to constrain finding a solution for the combination by representing the solution as a linear combination of functions.

9. The system of claim 1, wherein said comparing is performed using Matching Pursuit.

10. The system of claim 1, wherein the one or more computer subsystems are further configured for generating the simulated difference images, and wherein said simulating comprises simulating an image generated by the detector for the one or more patterned features formed on the specimen with one of the different perturbations and subtracting the reference image for the one or more patterned features from the simulated image to thereby generate one of the simulated difference images.

11. The system of claim 1, wherein the one or more patterned features cannot be resolved in the images generated by the detector.

12. The system of claim 1, wherein the one or more computer subsystems are further configured for generating a reconstructed image of the one or more patterned features from the one or more determined boundaries, and wherein a resolution of the reconstructed image is higher than a resolution of the images generated by the detector.

13. The system of claim 1, wherein the specimen comprises a wafer.

14. The system of claim 1, wherein the specimen comprises a reticle.

15. The system of claim 1, wherein the energy directed to the specimen comprises light, and wherein the energy detected from the specimen comprises light.

16. The system of claim 1, wherein the energy directed to the specimen comprises electrons, and wherein the energy detected from the specimen comprises electrons.

17. A non-transitory computer-readable medium, storing program instructions executable on a computer system for performing a computer-implemented method for determining boundaries of one or more patterned features formed on a specimen from an unresolved image of the one or more patterned features on the specimen, wherein the computer-implemented method comprises:

generating a difference image for one or more patterned features formed on a specimen by subtracting a reference image from an image generated by a detector for the one or more patterned features, wherein an inspection subsystem comprises at least an energy source and the detector, wherein the energy source is configured to generate energy that is directed to the specimen, wherein the detector is configured to detect energy from the specimen and to generate images responsive to the detected energy, and wherein the one or more patterned features formed on the specimen are unresolved in the images generated by the detector;

comparing the difference image to different simulated difference images, wherein the different simulated difference images are generated by simulating images generated for the one or more patterned features formed on the specimen with different perturbations, respectively;

based on results of the comparing, assigning an amplitude to each of the different perturbations; and

determining one or more boundaries of the one or more patterned features formed on the specimen by applying the different perturbations to one or more designed boundaries of the one or more patterned features with the assigned amplitudes.

18. A computer-implemented method for determining boundaries of one or more patterned features formed on a specimen from an unresolved image of the one or more patterned features on the specimen, comprising:

generating a difference image for one or more patterned features formed on a specimen by subtracting a reference image from an image generated by a detector for the one or more patterned features, wherein an inspection subsystem comprises at least an energy source and the detector, wherein the energy source is configured to generate energy that is directed to the specimen, wherein the detector is configured to detect energy from the specimen and to generate images responsive to the detected energy, and wherein the one or more patterned features formed on the specimen are unresolved in the images generated by the detector;

comparing the difference image to different simulated difference images, wherein the different simulated difference images are generated by simulating images generated for the one or more patterned features formed on the specimen with different perturbations, respectively;

based on results of the comparing, assigning an amplitude to each of the different perturbations; and

determining one or more boundaries of the one or more patterned features formed on the specimen by applying the different perturbations to one or more designed boundaries of the one or more patterned features with the assigned amplitudes, wherein said generating, said comparing, said assigning, and said determining are performed by one or more computer subsystems.