INTEGRATED USE OF MODEL-BASED METROLOGY AND A PROCESS MODEL

• US 20140172394A1
• Filed: 12/16/2013
• Published: 06/19/2014
• 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
• Granted Patent: US 10,769,320 B2
• Time in Patent Office: Days
• US Class Current: 703/6
• 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:

receiving an amount of measurement data associated with measurements of a target structure by a metrology tool;

determining 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 and a metrology based target model; and

storing the set of parameter values in a memory.

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

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, 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.

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

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

10. The method of claim 7, 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.

11. The method of claim 7, 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.

12. The method of claim 7, 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.

13. A method comprising:

receiving an amount of measurement data associated with measurements of a target structure by a metrology tool;

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; and

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

14. The method of claim 13, 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.

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

16. The method of claim 15, further comprising:

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

17. 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.

18. The method of claim 13, further comprising:

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

19. The method of claim 13, 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.

20. The method of claim 13, 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.

21. A system comprising:

an optical metrology tool including an illumination source and a detector configured to perform measurements of a target structure; and

a computing system configured to;

receive an amount of measurement data associated with measurements of a target structure by the metrology tool;

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 and a metrology based target model; and

store the set of parameter values in a memory.

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

23. The system of claim 22, 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.

24. The system of claim 21, wherein the integrated measurement model is based on simulation results from a process-based target model.

25. The system of claim 21, 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.

26. The system of claim 25, 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.

27. The system of claim 25, 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.

28. A system comprising:

a metrology tool including an illumination source and a detector configured to perform measurements of a target structure; and

a computing system configured to;

receive an amount of measurement data associated with measurements of a target structure by the metrology tool;

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; and

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

29. The system of claim 28, 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.

30. The system of claim 28, 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.

31. The system of claim 28, 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.