Overlay metrology based on a fringe pattern

Abstract

Measuring overlay using a microscope-based sensor, which provides the ability to measure alignment and overlay with a single system, or other or additional advantages. The signal from the sensor is an intensity modulated fringe pattern (e.g., an interference pattern). The sensor is configured to generate the intensity modulated fringe pattern based on diffracted radiation received from a first metrology mark in a first layer of a patterned substrate and a second metrology mark in a second layer of the patterned substrate. The intensity modulated fringe pattern is filtered for an expected fringe period. An amplitude, phase, and/or other parameter of fringes of the filtered fringe pattern are used to determine an overlay value.

Dependencies are inferred from the claim text.