摘要:
A pattern formed on a substrate includes first and second sub-patterns positioned adjacent one another and having respective first and second periodicities. The pattern is observed to obtain a combined signal which includes a beat component having a third periodicity at a frequency lower than that of the first and second periodicities. A measurement of performance of the lithographic process is determined by reference to a phase of the beat component. Depending how the sub-patterns are formed, the performance parameter might be critical dimension (CD) or overlay, for example. For CD measurement, one of the sub-patterns may comprise marks each having of a portion sub-divided by product-like features. The measurement can be made using an existing alignment sensor of a lithographic apparatus. Sensitivity and accuracy of the measurement can be adjusted by selection of the first and second periodicities, and hence the third periodicity.
摘要:
An alignment measurement system measures an alignment target on an object. A measurement illuminates the target and is reflected. The reflected measurement beam is split and its parts are differently polarized. A detector receives the reflected measurement beam. A processing unit determines alignment on the basis of the measurement beam received by the detector. An alternative arrangement utilizes an optical dispersive fiber to guide a multi-wavelength measurement beam reflected from the object to a detector.
摘要:
An alignment mark determines alignment of a first and a second exposure on a substrate on a macro level and a micro level. The alignment mark includes a first alignment pattern projected during the first exposure and a second alignment pattern projected during the second exposure. The alignment mark includes a first sub-mark at least partially defined by the first alignment pattern and a second sub-mark at least partially defined by the second alignment pattern. Relative positions of the first and second sub-marks on the substrate are representative for alignment of the first and second exposures on the macro level. At least one sub-mark is defined by image lines of the first alignment pattern and the second alignment pattern, and wherein relative positions of image lines of the first alignment pattern and image lines of the second alignment pattern of the at least one sub-mark are representative for alignment of the first and second exposures on the micro level.