METHOD AND APPARATUS TO DETERMINE A PATTERNING PROCESS PARAMETER

• US 20170255737A1
• Filed: 02/28/2017
• Published: 09/07/2017
• Est. Priority Date: 03/01/2016
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: VAN LEEST, Adriaan Johan, Tsiatmas, Anagnostis, Hinnen, Paul Christiaan, McNamara, Elliott Gerard, Verma, Alok, Theeuwes, Thomas, Cramer, Hugo Augustinus Joseph
• Granted Patent: US 10,453,758 B2
• Time in Patent Office: 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: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 7/70683 Mark designs
• CPC Class Codes: G03F 9/7003 Alignment type or strategy, e.g. leveling, global alignment
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

A method of determining a parameter of a patterning process, the method including: obtaining a detected representation of radiation redirected by a structure having geometric symmetry at a nominal physical configuration, wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the structure; and determining, by a hardware computer system, a value of the patterning process parameter based on optical characteristic values from an asymmetric optical characteristic distribution portion of the detected radiation representation with higher weight than another portion of the detected radiation representation, the asymmetric optical characteristic distribution arising from a different physical configuration of the structure than the nominal physical configuration.

Claims

1. A method of determining a parameter of a patterning process, the method comprising:

obtaining a detected representation of radiation redirected by a structure having geometric symmetry at a nominal physical configuration, wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the structure; and

determining, by a hardware computer system, a value of the patterning process parameter based on optical characteristic values from an asymmetric optical characteristic distribution portion of the detected radiation representation with higher weight than another portion of the detected radiation representation, the asymmetric optical characteristic distribution arising from a different physical configuration of the structure than the nominal physical configuration.

2. The method of claim 1, wherein the patterning process parameter is overlay and the different physical configuration is a shift of at least part of the structure relative another part of the structure.

3. The method of claim 1, wherein the detected radiation representation is a pupil representation.

4. The method of claim 1, wherein the detected radiation was primarily zeroth order radiation.

5. The method of claim 1, wherein the detected radiation representation is processed to subtract optical characteristic values across an axis of symmetry so as to reduce or eliminate the optical characteristic values of a symmetric optical characteristic distribution of the detected radiation representation.

6. The method of claim 1, wherein the value of the patterning process parameter is determined using a summation for a plurality of pixels of the detected radiation representation of an optical characteristic value for each pixel multiplied by an associated weighting for that pixel.

7. The method of claim 1, wherein the optical characteristic is intensity and/or phase.

8. The method of claim 1, wherein the structure is a device structure.

9. The method of claim 1, wherein the structure is a non-device structure within a substrate die comprising a device structure.

10. The method of claim 1, wherein the weighting is configured to cause a first type of the patterning process parameter to be determined for the different physical configuration separately from a second type of the patterning process parameter that is also obtainable from the same optical characteristic values, wherein the first type of patterning process parameter is in a different direction than the second type of patterning process parameter or between a different combination of parts of the unit cell than the second type of patterning process parameter.

11. The method of claim 10, further comprising a weighting configured to cause the second type of the patterning process parameter to be determined for the different physical configuration.

29. A metrology apparatus for measuring an object of a patterning process, the metrology apparatus configured to perform the method of claim 1.

30. A computer program product comprising a computer non-transitory readable medium having instructions recorded thereon, the instructions when executed by a computer implementing the method of claim 1.

12. A method of determining overlay of a patterning process, the method comprising:

obtaining a detected representation of radiation redirected by a structure having geometric symmetry at a nominal overlay value, wherein the detected representation of the radiation was obtained by illuminating a substrate with a radiation beam such that a beam spot on the substrate was filled with the structure and wherein, at a non-nominal value of the overlay, the physical configuration of the structure causes an asymmetric optical characteristic distribution in the detected radiation representation; and

determining, by a hardware computer system, a non-nominal value of the overlay of the structure based on a summation for a plurality of pixels of the detected radiation representation of an optical characteristic value for each pixel multiplied by an associated weighting for that pixel, wherein the weighting for pixels in the asymmetric optical characteristic distribution are different than the weighting for pixels in a symmetric optical characteristic distribution portion of the detected radiation representation.

13. The method of claim 12, wherein the detected radiation representation is a pupil representation.

14. The method of claim 12, wherein the detected radiation was primarily zeroth order radiation.

15. The method of claim 12, wherein the detected radiation representation is processed to subtract optical characteristic values across an axis of symmetry so as to reduce or eliminate the optical characteristic values of the symmetric optical characteristic distribution of the detected radiation representation.

16. The method of claim 12, wherein the optical characteristic is intensity and/or phase.

17. The method of claim 12, wherein the structure is a device structure.

18. The method of claim 12, wherein the structure is a non-device structure within a substrate die comprising a device structure.

19. The method of claim 12, wherein the weighting is configured to separately determine a first type of overlay for the structure from a second type of overlay for the structure, that is also obtainable from the same optical characteristic values.

20. The method of claim 19, further comprising a weighting configured to separately determine, from the same optical characteristic values, the second type of overlay for the structure from the first type of overlay for the structure.

21. A method comprising:

obtaining a detected representation of radiation redirected by a structure that has geometric symmetry at a nominal physical configuration, wherein a different physical configuration of the structure than the nominal physical configuration causes an asymmetric optical characteristic distribution in the detected representation and a patterning process parameter measures change in the physical configuration; and

determining, by a hardware computer system, a value of the patterning process parameter at the different physical configuration using a reconstruction process that processes optical characteristic values derived from the detected representation.

22. The method of claim 21, further comprising processing the representation to subtract optical characteristic values across an axis of symmetry so as to reduce or eliminate the optical characteristic values of a symmetric optical characteristic distribution in the representation and the determining comprises determining the value of the patterning process parameter using a reconstruction process that processes optical characteristic values derived from the processed detected representation.

23. The method of claim 21, wherein the reconstruction process involves using a mathematical model of the structure to generate a simulated representation of radiation redirected by the structure for comparison with the optical characteristic values derived from the detected representation.

24. The method of claim 23, wherein the mathematical model is based on a profile of the structure derived from measurements of instances of the structure.

25. The method of claim 21, wherein the reconstruction process involves comparing the optical characteristic values derived from the detected representation against a library of simulated representations of radiation redirected by the structure.

26. A method comprising:

obtaining a detected representation of radiation redirected by a structure that has geometric symmetry at a nominal physical configuration, wherein a different physical configuration of the structure than the nominal physical configuration causes an asymmetric optical characteristic distribution in the detected representation and a patterning process parameter measures change in the physical configuration; and

determining, by a hardware computer system, a value of the patterning process parameter at the different physical configuration using a non-linear solver that processes optical characteristic values derived from the detected representation.

27. The method of claim 26, wherein the non-linear solver solves a function wherein the one or more variable terms thereof consist only of one or more variable terms having the patterning process parameter as the variable to an odd power, and/or one or more variable terms having the patterning process parameter as the variable in combination with another parameter of the structure as a variable.

28. The method of claim 26, further comprising processing the representation to subtract optical characteristic values across an axis of symmetry so as to reduce or eliminate the optical characteristic values of a symmetric optical characteristic distribution in the representation and the determining the value of the patterning process parameter using a non-linear solver that processes optical characteristic values derived from the processed detected representation.