Patent attributes
A structure for overlay measurement is provided in the present invention, using the diffraction characteristics on the boundary portion between two microstructures formed on each of two material layers. The optical intensity distribution on the boundary portion between microstructures formed on the two overlaid material layers respectively are measured by an optical microscope to obtain the overlay error between the two overlaid material layers. In addition, the present invention also provides a method for overlay measurement using the structure for overlay measurement, wherein a merit relation based on the optical intensity distribution on the boundary portion between different microstructures is determined. The merit relation can be used to analyze the overlay error to improve the efficiency and accuracy of on-line error measurement.
