Metrology method and apparatus
A method comprising: evaluating a plurality of polarization characteristics associated with measurement of a metrology target of a substrate processed using a patterning process, against one or more measurement quality parameters; and selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
1. A method comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
2. The method of claim 1 , wherein the polarization characteristics further comprise phase differences between orthogonal polarization components.
3. The method of claim 1 , wherein the polarization angles comprise polarization angles of radiation that illuminate the metrology target in the measurement of the metrology target.
4. The method of claim 1 , wherein the polarization angles comprise polarization angles of a polarizer of a detector that detects radiation that reflects from the metrology target in the measurement of the metrology target.
5. The method of claim 2 , wherein the polarization characteristics comprise phase differences between orthogonal polarizations of radiation that illuminate the metrology target in the measurement of the metrology target.
6. The method of claim 2 , wherein the polarization characteristics comprise phase differences imparted by a retarder of a detector that detects radiation that reflects from the metrology target in the measurement of the metrology target.
7. The method of claim 1 , wherein the measurement quality parameters comprise one or more of stack sensitivity, overlay sensitivity, or diffraction efficiency.
8. The method of claim 1 , wherein the selecting comprises selecting one or more polarization characteristics from the plurality of polarization characteristics that result in one or more of the measurement quality parameters being within a certain finite range from a maximum or minimum value from among the evaluated plurality of polarization characteristics.
9. The method of claim 2 , wherein the selecting comprises selecting one or more polarization characteristics from the plurality of polarization characteristics that result in one or more of the measurement quality parameters reaching a threshold value.
10. The method of claim 9 , wherein the selecting comprises selecting one or more polarization characteristics from the plurality of polarization characteristics that result in another one or more of the measurement quality parameters being within a certain finite range from a maximum or minimum value from among the evaluated plurality of polarization characteristics that result in the one or more of the measurement quality parameters reaching a threshold value.
11. The method of claim 1 , wherein the evaluating is performed by simulation.
12. A measurement method comprising measuring a metrology target on a substrate according to one or more polarization angles selected in a method comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
13. A metrology apparatus for measuring a parameter of a lithographic process, the metrology apparatus being operable to perform the method comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
14. A non-transitory computer program product comprising machine-readable instructions for causing a processor to cause performance of operations comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
15. A system comprising:
an inspection apparatus configured to provide a beam of radiation on two adjacent periodic structures or measurement targets on a substrate and to detect radiation diffracted by the targets to determine a parameter of a patterning process; and
a non-transitory computer program product comprising machine-readable instructions for causing a processor to cause performance of operations comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters.
16. The system of claim 15 , further comprising a lithographic apparatus comprising a support structure configured to hold a patterning device to modulate a radiation beam and a projection optical system arranged to project the modulated radiation beam onto a radiation-sensitive substrate.
17. A method to optimize a metrology measurement comprising:
the method comprising:
evaluating a plurality of polarization characteristics against one or more measurement quality parameters, the plurality of polarization characteristics being associated with measurement of a metrology target of a substrate processed using a patterning process, wherein the polarization characteristics comprise polarization angles; and
selecting one or more polarization characteristics from the plurality of polarization characteristics based on one or more of the measurement quality parameters; and
selecting a pitch and other features of the metrology target so as to maximize one or more of the measurement quality parameters.