Integrated use of model-based metrology and a process model

• US 10,769,320 B2
• Filed: 12/16/2013
• Issued: 09/08/2020
• Est. Priority Date: 12/18/2012
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Kuznetsov, Alexander, Shchegrov, Andrei V., Pandev, Stilian Ivanov
• Primary Examiner(s): Toatley, Jr., Gregory J
• Assistant Examiner(s): Dinh, Lynda
• Application Number:
  US14/107,850
• Publication Number:
  US 20140172394A1
• Time in Patent Office: 2,458 Days
• Field of Search: 702127
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G03F 7/70641 Focus
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36

Abstract

Methods and systems for performing measurements based on a measurement model integrating a metrology-based target model with a process-based target model. Systems employing integrated measurement models may be used to measure structural and material characteristics of one or more targets and may also be used to measure process parameter values. A process-based target model may be integrated with a metrology-based target model in a number of different ways. In some examples, constraints on ranges of values of metrology model parameters are determined based on the process-based target model. In some other examples, the integrated measurement model includes the metrology-based target model constrained by the process-based target model. In some other examples, one or more metrology model parameters are expressed in terms of other metrology model parameters based on the process model. In some other examples, process parameters are substituted into the metrology model.

Claims

1. A method comprising:

providing illumination radiation to a target structure fabricated on a semiconductor wafer, the illumination radiation provided by an illumination source of a metrology tool;

detecting an amount of radiation from the target structure in response to the illumination radiation, the amount of radiation detected by a detector of the metrology tool;

generating a measured response associated with the target structure based on the detected radiation, the measured response comprising an amount of measurement data;

determining a set of geometric parameter values characterizing the target structure and one or more process parameter values characterizing a fabrication process employed by a semiconductor process tool to fabricate the target structure on the semiconductor wafer based on a fitting of the amount of measurement data to an integrated measurement model of the target structure, wherein the integrated measurement model is based on a process based target model that constrains values of one or more of the set of geometric parameters characterizing the target structure based on a range of achievable values of one or more fabrication process parameters of the process based target model and a metrology based target model that predicts the measured response based on a model of an interaction of the target structure with the metrology tool; and

communicating the one or more process parameter values to the semiconductor process tool, that causes the semiconductor process tool to adjust one or more process parameters of the semiconductor process tool to achieve a desired target structure.

2. The method of claim 1, wherein the process-based target model characterizes the target structure in terms of at least one process parameter.

3. The method of claim 2, further comprising:

generating the integrated measurement model based on a linkage between one or more parameters of the process-based target model and one or more parameters of the metrology-based target model.

4. The method of claim 3, wherein the linkage is a constraint on a range of values of a metrology model parameter determined based on a range of process model parameter values.

5. The method of claim 3, wherein the linkage is a constraint on the one or more metrology parameters determined from the process-based target model.

6. The method of claim 3, wherein the linkage is a functional relationship between two or more metrology model parameters determined from the process-based target model.

7. The method of claim 1, wherein the one or more process parameters are parameters of the integrated measurement model of the target structure.

8. The method of claim 1, wherein the one or more process parameters are the only parameters of the integrated measurement model of the target structure.

9. The method of claim 1, wherein the determining of the one or more process parameter values involves determining one or more metrology parameter values based on the fitting of the amount of measurement data to the integrated measurement model and determining the one or more process parameter values based on a functional relationship between the one or more process parameters and the one or more metrology parameters.

10. The method of claim 1, wherein the determining of the one or more process parameter values involves transforming the measurement data to principal components and determining the one or more process parameter values directly from the principal components.

11. The method of claim 1, wherein the one or more process parameter values include any of a depth of focus value, an exposure value, an etch time, and a deposition time.

12. A method comprising:

providing illumination radiation to a target structure fabricated on a semiconductor wafer, the illumination radiation provided by an illumination source of a metrology tool;

detecting an amount of radiation from the target structure in response to the illumination radiation, the amount of radiation detected by a detector of the metrology tool;

generating a measured response associated with the target structure based on the detected radiation, the measured response comprising an amount of measurement data;

determining one or more process parameter values characterizing a process employed to generate the target structure based on the amount of measurement data and an integrated measurement model of the target structure, wherein the integrated measurement model is based on a process based target model that constrains values of one or more of the set of geometric parameters characterizing the target structure based on a range of achievable values of one or more fabrication process parameters of the process based target model and a metrology based target model that predicts the measured response based on a model of an interaction of the target structure with the metrology tool; and

storing the one or more process parameter values in a memory.

13. The method of claim 12, wherein the determining the one or more process parameter values involves determining at least one geometric parameter based on a fitting of the amount of measurement data to the metrology-based target model, and

determining the one or more process parameter values based on the process-based target model and the at least one geometric parameter.

14. The method of claim 13, wherein the process-based target model is a neural network model.

15. The method of claim 14, further comprising:

training the neural network model based at least in part on process model data.

16. The method of claim 13, wherein the integrated measurement model is a neural network model, and further comprising:

training the neural network model based at least in part on process model data and measurement signals corresponding to the process model data.

17. The method of claim 13, further comprising:

generating the integrated measurement model based on simulation results from a process-based target model.

18. The method of claim 12, wherein the one or more process parameter values include any of a depth of focus value, an exposure value, an etch time, and a deposition time.

19. The method of claim 12, wherein the determining of the one or more process parameter values characterizing a process involves transforming the measurement data to principal components and determining the one or more process parameter values directly from the principal components.

20. A system comprising:

an optical metrology tool including an illumination source providing illumination radiation to a target structure fabricated on a semiconductor wafer and a detector detecting an amount of radiation from the target structure in response to the illumination radiation, the optical metrology tool configured to generate a measured response associated with the target structure based on the detected radiation, the measured response comprising an amount of measurement data; and

a non-transitory, computer-readable medium, storing instructions that, when executed by one or more processors, cause the one or more processors to;

determine a set of parameter values characterizing the target structure based on a fitting of the amount of measurement data to an integrated measurement model of the target structure, wherein the integrated measurement model is based on a process based target model that constrains values of one or more of the set of geometric parameters characterizing the target structure based on one or more fabrication process parameters, of the process based target model by mathematically linking values of one or more parameters of the process based target model to values of one or more of the set of geometric parameters characterizing the target structure and a metrology based target model that predicts the measured response based on a model of an interaction of the target structure with the metrology tool; and

store the set of parameter values in a memory.

21. The system of claim 20, wherein the process-based target model characterizes the target structure in terms of at least one process parameter.

22. The system of claim 21, wherein the integrated measurement model is based on a linkage between one or more parameters of the process-based target model and one or more parameters of the metrology-based target model.

23. The system of claim 20, wherein the integrated measurement model is based on simulation results from a process-based target model.

24. The system of claim 20, further comprising:

determining one or more process parameter values based on a fitting of the amount of measurement data to the integrated measurement model of the target structure; and

storing the one or more process parameter values in a memory.

25. The system of claim 24, wherein the determining of the one or more parameter values involves transforming the measurement data to principal components and determining the one or more process parameter values directly from the principal components.

26. The system of claim 24, wherein the one or more process parameter values include any of a depth of focus value, an exposure value, an etch time, and a deposition time.

27. A system comprising:

an illumination source of a metrology tool that provides illumination radiation to a target structure fabricated on a semiconductor specimen;

a detector of the metrology tool that detects light from the target structure in response to the illumination light and generates a measured spectral response, the measured spectral response comprising an amount of measurement data;

a non-transitory, computer-readable medium, storing instructions that, when executed by one or more processors, cause the one or more processors to;

determine one or more process parameter values characterizing a process employed to generate the target structure based on the amount of measurement data and an integrated measurement model of the target structure, wherein the integrated measurement model is based on a process based target model that constrains values of one or more of the set of geometric parameters characterizing the target structure based on a range of achievable values of one or more fabrication process parameters of the process based target model and a metrology based target model that predicts the measured response based on a model of an interaction of the target structure with the metrology tool; and

store the one or more process parameter values in a memory.

28. The system of claim 27, wherein the determining the one or more process parameters involves

determining at least one geometric parameter based on a fitting of the amount of measurement to the metrology-based target model, and

determining the one or more process parameter values based on the process-based target model and the at least one geometric parameter.

29. The system of claim 27, wherein the determining of the one or more process parameter values involves transforming the measurement data to principal components and determining the one or more process parameter values directly from the principal components.

30. The system of claim 27, wherein the one or more process parameter values include any of a depth of focus value, an exposure value, an etch time, and a deposition time.