Diffractive overlay mark

A method and apparatus for calculating overlay based on high order diffraction phase measurements are provided. Embodiments include forming a first diffraction pattern in a first layer of a wafer; forming a second diffraction pattern in a second layer of the wafer, the second layer being formed over...

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1. Verfasser: TANG, MING HAO
Format: Patent
Sprache:chi ; eng
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Zusammenfassung:A method and apparatus for calculating overlay based on high order diffraction phase measurements are provided. Embodiments include forming a first diffraction pattern in a first layer of a wafer; forming a second diffraction pattern in a second layer of the wafer, the second layer being formed over the first layer; detecting a first or a higher odd order signal in an X and a Y direction from each of the first and second diffraction patterns; calculating a peak for each signal; measuring a delta value between peaks of the signals in the X direction and a delta value between peaks of the signals in the Y direction; and calculating an overlay between the first and second layers based on the delta values.