Measurement and correction of sample holder and stage tilt in metrology systems

Mechanical spacing elements and active control methods in metrology systems correct sample holder tilts, ensuring precise alignment and improved measurement accuracy by bypassing tight manufacturing tolerances and motorized mechanisms, enhancing stability and reducing costs.

WO2026114611A1PCT designated stage Publication Date: 2026-06-04CARL ZEISS SMT GMBH
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
CARL ZEISS SMT GMBH
Filing Date
2025-11-04
Publication Date
2026-06-04

AI Technical Summary

Technical Problem

Metrology systems, particularly scanning electron microscopes, face challenges in achieving precise alignment between the charged particle beam and the sample surface due to mechanical tolerances and assembly variations, leading to undesired tilts in the sample holder, which affect measurement accuracy and image quality, especially in large wafer tools.

Method used

The use of mechanical spacing elements, such as shims and wedges, to adjust the spatial arrangement of the sample holder and stage components, combined with active control of stage movement, to align the sample holder surface with the desired orientation and position, without relying on tight manufacturing tolerances or motorized mechanisms.

Benefits of technology

This approach provides precise and stable alignment, improving measurement accuracy and image quality by directly transmitting forces through solid mechanical interfaces, reducing complexity and cost, and enhancing dynamic properties and stability over time.

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Abstract

Methods and systems are provided for aligning a sample holder in a metrology system. The metrology system includes a process module mounted on a vacuum chamber interface and defining a process axis, a sample stage assembly with translational and rotational stages, and a sample holder configured to hold a sample. The method includes determining an actual spatial arrangement of the sample holder surface, calculating required spatial corrections, and adjusting the sample holder surface to achieve a desired spatial arrangement using spacing elements disposed between adjacent components in the mechanical stack of system components. The spacing elements may be separate removable elements or integrally formed features of one or more components in the mechanical stack of system components. Multiple measurements at different rotational and translational positions enable separation of sample holder tilt and rotation stage tilt components. Additionally, or alternatively, active control parameters for at least one linear sample stage may be determined to maintain working distance during operation. The system achieves repeatable and stable sample holder alignment without tight manufacturing tolerances or movable adjustment mechanisms.
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