Managing and using metrology data for process and equipment control

• US 20080009081A1
• Filed: 07/10/2006
• Published: 01/10/2008
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Madriaga, Manuel, Vuong, Vi, Bao, Junwei
• Granted Patent: US 7,526,354 B2
• Time in Patent Office: Days
• US Class Current: 438/16
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01N 2021/95615 with stored comparision signal
• CPC Class Codes: G01N 21/4788 Diffraction for sizing particles G01N15/0205
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness

Abstract

An apparatus to examine a patterned structure formed on a semiconductor wafer using an optical metrology model includes a fabrication system and a metrology processor. The fabrication system includes a fabrication cluster, metrology cluster, metrology model optimizer, and real time profile estimator. The fabrication cluster is configured to process wafers, the wafers having patterned and unpatterned structures. The patterned structures have underlying film thicknesses, critical dimension, and profile. The metrology cluster includes one or more optical metrology devices. The metrology cluster is configured to measure diffraction signals off the patterned and the unpatterned structures. The metrology model optimizer is configured to optimize an optical metrology model of the patterned structure using one or more measured diffraction signals off the patterned structure and with floating profile parameters, material refraction parameters, and metrology device parameters. The real time profile estimator is configured to use the optimized optical metrology model from the metrology model optimizer, the measured diffraction signals off the patterned structure, and a fixed value within the range of values for at least one parameter from amongst the material refraction parameters and the metrology device parameters. The real time profile estimator is configured to create an output comprising underlying film thickness, critical dimension, and profile of the patterned structure. The metrology data processor is configured to receive, process, store, and transmit the fixed value within the range of values for the at least one parameter from amongst the material refraction parameters and the metrology device parameters.

Claims

1. An apparatus for examining a patterned structure formed on a semiconductor wafer using an optical metrology model, the system comprising:

a first fabrication system comprising;

a first fabrication cluster configured to process wafers, the wafers having a first patterned and a first unpatterned structures, the first patterned structures having underlying film thicknesses, critical dimension, and profile;

a first metrology cluster including one or more optical metrology devices coupled to the first fabrication cluster, the first metrology cluster configured to measure diffraction signals off the first patterned and the first unpatterned structures;

a first metrology model optimizer coupled to the first fabrication cluster and the first metrology cluster, the first metrology model optimizer configured to optimize an optical metrology model of the first patterned structure using one or more measured diffraction signals off the first patterned structure and with floating profile parameters, material refraction parameters, and metrology device parameters;

a first real time profile estimator coupled to the first optical model optimizer and the first metrology cluster, configured to use the optimized optical metrology model from the first metrology model optimizer, the measured diffraction signals off the first patterned structure, and a fixed value within the range of values for at least one parameter from amongst the material refraction parameters and the metrology device parameters, and wherein the first real time profile estimator is configured to create an output comprising underlying film thickness, critical dimension, and profile of the first patterned structure; and

a metrology processor coupled to the first fabrication system, the metrology data processor configured to receive, process, store, and transmit the fixed value within the range of values for the at least one parameter from amongst the material refraction parameters and the metrology device parameters.

2. The apparatus of claim 1 wherein the metrology processor is further configured to receive, process, store, and transmit the optimized optical metrology model, and underlying film thickness, profile parameters, critical dimension, material refractive parameters, and metrology device parameters of the first patterned structure.

3. The apparatus of claim 1 the first fabrication system further comprises:

a first profile server coupled to the first optical model optimizer and the first metrology cluster, configured to use the optimized optical metrology model from the first optical metrology model optimizer, the measured diffraction signals off the first patterned structure, and the fixed value, and wherein the first profile server is configured to create an output comprising underlying film thickness, critical dimension, and profile of the first patterned structure.

4. The apparatus of claim 1 wherein the material refraction parameters include refractive indices (N) parameter and extinction coefficients (K) parameter.

5. The apparatus of claim 4 wherein the N parameter is represented by a vector a in the expression N(λ

, a) and the K parameter is represented by b in the expression K(λ

, b), wherein λ

is the wavelength.

6. The apparatus of claim 5 wherein the N parameter and K parameter are fixed to an N and K values of layers of the patterned structure measured using the first optical metrology cluster.

7. The apparatus of claim 6 wherein the N and K values of layers of the first patterned structure were measured from the first unpatterned structure or an unpatterned area in the same wafer or an unpatterned area of a test wafer.

8. The apparatus of claim 7 wherein at least 2 sites on a wafer are measured and a statistical average is calculated.

9. The apparatus of claim 5 wherein the N parameter and K parameter are fixed to empirical or theoretical N and K values for the same material.

10. The apparatus of claim 9 wherein the metrology device parameters include angle of incidence and/or azimuth angle.

11. The apparatus of claim 1 further comprising

a metrology data store coupled to the metrology data processor, the metrology data store configured to store and access the optimized optical metrology model and the fixed value of the first patterned structure.

12. The apparatus of claim 11 wherein the metrology data store is configured to store and access pairs of simulated diffraction signals and corresponding sets of profile parameters for the first patterned structure.

13. The apparatus of claim 11 wherein the metrology data store is configured to store and access sets of training data for an optical metrology machine language system and/or a trained optical metrology machine language system for the first patterned structure.

14. The apparatus of claim 11 wherein the metrology data processor is coupled to a second fabrication system.

15. The apparatus of claim 14 wherein the second fabrication system is configured to process the wafer, the wafer having a second patterned and a second unpatterned structure, the second patterned structure having underlying film thicknesses, critical dimension, and profile, the second fabrication system comprising:

a second fabrication cluster configured to process wafers, the wafers having a second patterned and a second unpatterned structures, the first patterned structures having underlying film thicknesses, critical dimension, and profile;

a second metrology cluster including one or more optical metrology devices coupled to the second fabrication cluster, the second metrology cluster configured to measure diffraction signals off the second patterned and the second unpatterned structure;

a second metrology model optimizer coupled to the second fabrication cluster and the second metrology cluster, the second metrology model optimizer configured to optimize a second optical metrology model of the second patterned structure using one or more measured diffraction signals off the second patterned structure and with floating profile parameters, material refraction parameters, and metrology device parameters;

a second real time profile estimator coupled to the second optical model optimizer and the second metrology cluster, configured to use the optimized optical metrology model from the second metrology model optimizer, the measured diffraction signals off the second patterned structure, and a fixed value with the range of values for at least one parameter from amongst the material refraction parameters and the metrology device parameters, and wherein the second real-time profile estimator is configured to create an output comprising underlying film thickness, critical dimension, and profile of the second patterned structure.

16. The apparatus of claim 15 the second fabrication system further comprises:

a second profile server coupled to the second optical model optimizer and the second metrology cluster, configured to use the optimized optical metrology model from the second optical metrology model optimizer, the measured diffraction signals off the second patterned structure, and the fixed value, and configured to create an output comprising underlying film thickness, critical dimension, and profile of the second patterned structure.

17. The apparatus of claim 16 wherein at least one of the underlying film thickness, critical dimension, and profile of the first patterned structure is used to alter at least one process parameter of the second fabrication cluster.

18. The apparatus of claim 16 wherein at least one of the underlying film thickness, critical dimension, and profile of the second patterned structure is used to alter at least one process parameter of the first fabrication cluster.

19. The apparatus of claim 16 wherein at least one of the underlying film thickness, critical dimension, and profile of the first patterned structure is used to alter at least one process parameter of the first fabrication cluster.

20. The apparatus of claim 16 wherein at least one of the underlying film thickness, critical dimension, and profile of the second patterned structure is used to alter at least one process parameter of the second fabrication cluster.

21. The apparatus of claim 16 wherein the metrology data store is configured to store and access pairs of simulated diffraction signals and corresponding sets of profile parameters for the second patterned structure.

22. The apparatus of claim 16 wherein the metrology data store is configured to store and access sets of training data for an optical metrology machine language system and/or a trained optical metrology machine language system for the second patterned structure.

23. The apparatus of claim 16 wherein the metrology processor is configured to receive, process, and transmit metrology data from and to offline or remote metrology data sources.

24. The apparatus of claim 16 wherein the metrology processor is coupled to a process simulator.

25. The apparatus of claim 16 wherein the metrology processor is coupled to a process simulator and the metrology processor is configured to receive and process metrology data from other sources and/or to process and transmit metrology data from the process simulators, including values of profile parameters, material refraction parameters, and metrology device parameters to other fabrication systems.

26. A method of managing metrology data related to structures in a wafer undergoing one or more fabrication processes, the method comprising:

a) creating an optical metrology model for the patterned structure, the optical metrology model having profile parameters, material refraction parameters, and metrology device parameters;

b) defining ranges of values for the profile parameters, material refraction parameters, and metrology device parameters;

c) obtaining one or more measured diffraction signals of the patterned structure;

d) optimizing the optical metrology model to obtain an optimized optical metrology model using the ranges of values defined in b) and the one or more measured diffraction signals of the patterned structure obtained in c);

e) for at least one parameter from amongst the material refraction parameters and the metrology device parameters, setting the at least one parameter to a fixed value within the range of values for the at least one parameter;

f) generating one or more metrology data stores using the optimized optical metrology model, wherein the one or more metrology data stores are used to determine the profile parameters of the patterned structure;

g) determining the profile parameters of the patterned structure using a measured diffraction signal off the patterned structure and the one or more generated metrology data stores; and

h) associating the determined patterned structure profile parameters to identifying information related to material data, metrology device data, location of the patterned structure in the wafer, wafer identification, and/or fabrication step identification.

27. The method of claim 26 further comprising:

i1) storing the associated patterned structure profile parameters and identifying information in a metrology data store.

28. The method of claim 27 further comprising:

i2) using the patterned structure profile parameters and/or identifying information to modify at least one process variable or modify a setting of a fabrication device in a fabrication cluster in the fabrication system.

29. The method of claim 28 further comprising:

i3) transmitting the patterned structure profile parameters and/or identifying information to another fabrication system, wherein the profile parameters are used to modify at least one process variable of the another fabrication system.

30. The method of claim 28 wherein the another fabrication system is for a prior fabrication step of the wafer application.

31. The method of claim 30 wherein the another fabrication system is for a later fabrication step of the wafer application.