Methods and apparatus for obtaining diagnostic information relating to an industrial process
In a lithographic process, product units such as semiconductor wafers are subjected to lithographic patterning operations and chemical and physical processing operations. Alignment data or other measurements are made at stages during the performance of the process to obtain object data representing positional deviation or other parameters measured at points spatially distributed across each unit. This object data is used to obtain diagnostic information by performing a multivariate analysis to decompose a set of vectors representing the units in the multidimensional space into one or more component vectors. Diagnostic information about the industrial process is extracted using the component vectors. The performance of the industrial process for subsequent product units can be controlled based on the extracted diagnostic information.
1. A non-transitory computer program product comprising machine readable instructions stored therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:
obtain measurement data comprising measurement values corresponding to different modes of measurement of a sensor system configured to sample on one or more marks on a physical product unit that has been subjected to a semiconductor manufacturing process;
identify one or more components indicative of deformation of the one or more marks based on a result of a multivariate analysis applied to the measurement data or to previous measurement data; and
use the measurement data and the identified one or more components to determine a preferred mode of measurement for the sensor system based on a reduced impact of the deformation of the one or more marks on the accuracy of a measurement value obtained by the sensor system.
2. The computer program product of claim 1 , wherein the measurement values are associated with an overlay parameter and the one or more marks are overlay marks.
3. The computer program product of claim 2 , wherein the mode of measurement of the sensor system is a wavelength of radiation used by the sensor system to sample the one or more marks.
4. The computer program product of claim 3 , wherein the instructions are further configured to cause the computer system to select one or more further marks based on a further reduction of the impact of the mark deformation on the accuracy.
5. The computer program product of claim 1 , wherein the identified one or more components are further based on performance data comprising measurement values corresponding to measurements by a different sensor.
6. The computer program product of claim 1 , wherein the multivariate analysis is a Principal Component Analysis (PCA) and the components are principal components.
7. The computer program product of claim 6 , wherein the components are based on a result of a PCA analysis applied to previous measurement data and the components are stored in a library.
8. The computer program product of claim 1 , wherein the components are expressed as vectors in a multidimensional space.
9. The computer program product of claim 8 , wherein the multidimensional space is a space of reduced dimensions.
10. The computer program product of claim 1 , wherein the multivariate analysis is an Independent Component Analysis (ICA).
11. The computer program product of claim 1 , wherein the instructions are further configured to cause the computer system to generate a recipe for the sensor system based on the preferred mode of measurement.
12. The computer program product of claim 1 , wherein the sensor system is a metrology tool.
13. A metrology tool comprising the computer program product according to claim 1 , wherein the sensor system is the metrology tool.
14. The computer program product of claim 1 , wherein the sensor system is an alignment sensor of a lithographic apparatus and the one or more marks are alignment marks.
15. The computer program product of claim 14 , wherein the mode of measurement of the alignment sensor is a wavelength of radiation used by the alignment sensor to sample the alignment marks.
16. The computer program product of claim 15 , wherein the instructions are further configured to cause the computer system to select one or more further alignment marks based on a further reduction of the impact of deformation of the alignment marks on the accuracy.
17. A lithographic apparatus comprising:
an alignment sensor; and
the computer program product of claim 1 , wherein the sensor system is the alignment sensor and the one or more marks are alignment marks.
18. A method comprising:
obtaining measurement data comprising measurement values corresponding to different modes of measurement of a sensor system configured to sample on one or more marks on a physical product unit that has been subjected to a semiconductor manufacturing process;
identifying, by a hardware computer system, one or more components indicative of deformation of the one or more marks based on a result of a multivariate analysis applied to the measurement data or previous measurement data; and
using the measurement data and the identified one or more components to determine a preferred mode of measurement for the sensor system based on a reduced impact of the deformation of the one or more marks on the accuracy of a measurement value obtained by the sensor system.
19. The method of claim 18 , wherein the measurement values are associated with an overlay parameter and the one or more marks are overlay marks.
20. The method of claim 19 , wherein the mode of measurement of the sensor system is a wavelength of radiation used by the sensor system to sample the one or more marks.