System and method for overlay error detection

Abstract

A method is provided for overlay error detection in a bonded wafer. The method includes receiving a bonded wafer in a bonding chamber, where the bonded wafer includes a first structure bonded to a second structure at a bonding interface. The first structure includes first overlay targets aligned with second overlay targets of the second structure at the bonding interface. The method further includes illuminating a first light beam onto a first portion of the bonded wafer for a first time duration that includes a start time. A light detector is used to detect a first temperature map of a region of the bonded wafer around the first portion illuminated by the first light beam, with the first temperature map being detected after the start time for a second time duration. Based on the first temperature map, an overlay error at the bonding interface is determined from misalignment between the first overlay targets and the second overlay targets.

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