Differential FET structures for electrical monitoring of overlay

摘要

A method and apparatus for determining overlay includes an array of electronic devices having structures formed in a plurality of layers and such that a device on a first end of the array includes an offset from a position of a device on a second end of the array. A measurement device is configured to measure electrical characteristics of the devices in the array to determine a transition position between the electrical characteristics. A comparison device is configured to determine an overlay between the layers based on a device associated with the transition position.