System and method for overlay error detection

The thermal-based measurement approach using overlay targets with varying thermal conductivity and thermal imaging addresses the limitations of existing techniques, offering a cost-effective and efficient method for detecting overlay alignment errors in semiconductor bonding, suitable for high-volume manufacturing environments.

WO2026155774A1PCT designated stage Publication Date: 2026-07-23TOKYO ELECTRON LTD +1
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
TOKYO ELECTRON LTD
Filing Date
2025-09-05
Publication Date
2026-07-23

AI Technical Summary

Technical Problem

Current microscopy-based and scatterometry-based techniques for overlay alignment error detection in semiconductor bonding processes are limited by equipment costs, complexity, and throughput, making them impractical for high-volume manufacturing environments.

Method used

A thermal-based measurement approach using specially designed overlay targets with varying thermal conductivity, combined with thermal imaging, to detect alignment errors by analyzing temperature maps generated through rapid heating or cooling of the bonded wafer.

Benefits of technology

This method provides a cost-effective, fast, and accurate solution for detecting overlay errors in high-volume manufacturing, enabling rapid, non-destructive measurements with high precision and improved efficiency, reducing the need for expensive and complex X-ray exposure.

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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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