CPC G03F 7/70641 (2013.01) [G03F 9/7026 (2013.01); G03F 9/7076 (2013.01)] | 14 Claims |
1. A method for determining a focus parameter value used to expose a structure on a substrate, the method comprising:
obtaining measurement data relating to a measurement of the structure, wherein the structure comprises a single periodic structure per measurement location;
decomposing the measurement data into component data comprising first and second harmonic components of the measurement data;
processing the first and second harmonic components by determining a combination of amplitudes or phases of each of the first and second harmonic components to extract processed component data having a reduced dependence on non-focus related effects; and
determining the focus parameter value from the processed component data.
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