Multi-Detector Alignment Using Corner Secondary Electron Beams
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Solution Overview
Problem
Existing multi-beam inspection apparatuses face challenges in accurately aligning multiple secondary electron beams with detection elements, especially when a secondary electron detector is replaced or exchanged, affecting the precision of pattern inspection in semiconductor manufacturing.
Innovation Solution
A method and apparatus for aligning multiple secondary electron beams with a multi-detector, involving scanning the detection elements with the secondary electron beams, detecting corner beams, calculating positional relationships, and adjusting the detector's position to align the beams with the detection elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple secondary electron beams are used for high-speed inspection, then productivity is improved, but alignment precision between beams and detection elements deteriorates
Solution Approach 1:
The patent performs preliminary alignment calibration by detecting corner beams from corner patterns before actual inspection. The system pre-determines the positional relationship between multiple secondary electron beams and detection elements, storing this alignment data for use during high-speed inspection operations, thus ensuring precision is established before productivity-critical operations begin
Solution Approach 2:
The patent replaces mechanical alignment adjustment mechanisms with an optical/electronic detection system. Instead of physically adjusting beam positions or detector positions using mechanical stages, the system uses corner beam detection and computational algorithms to determine and compensate for positional relationships, enabling high-speed electronic alignment without mechanical intervention
2Adaptability or versatility
If a secondary electron detector is replaced or exchanged, then adaptability is improved, but alignment precision deteriorates
Solution Approach 1:
The patent enables the system to self-align after detector replacement by automatically detecting corner beams and calculating the new positional relationship between beams and the replaced detector. The system performs self-calibration without requiring manual intervention or reference to previous alignment data, making the alignment process independent of detector history and enabling seamless detector replacement
Solution Approach 2:
The patent changes the alignment approach from fixed mechanical positioning to dynamic parameter calculation. When a detector is replaced, the system recalculates alignment parameters based on detected corner beam positions, adjusting the positional relationship data to match the new detector configuration, thus maintaining precision adaptability across detector replacements
3Measurement precision
If corner beams are detected for alignment calibration, then alignment precision is improved, but inspection time increases
Solution Approach 1:
The patent segments the alignment calibration process by focusing detection only on corner patterns and corner beams rather than attempting to detect or process all patterns. This segmentation of the calibration target to only corner elements reduces the complexity and time required for alignment while maintaining sufficient precision for the inspection system
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise alignment of secondary electron beams with detection elements, improving the accuracy of pattern inspection and maintaining high yield in semiconductor manufacturing by effectively handling detector replacements.
Implementation Method 1
irradiating an inspection target substrate with multiple electron beams and detecting a secondary electron corresponding to each beam emitted from the inspection target substrate
Implementation Method 2
a deflector configured to scan the plurality of first detection elements with the multiple secondary electron beams
Data Source
AI summary
A multiple secondary electron beam alignment method includes scanning a plurality of first detection elements of a multi-detector, which are arrayed in a grid, with multiple secondary electron beams emitted from a surface of a target object on a stage, detecting a plurality of beams including a corner beam located at a corner in the multiple secondary electron beams by the multi-detector, calculating a positional relationship between the plurality of beams including the corner beam and a plurality of second detection elements, which have detected the plurality of beams including the corner beam, in the plurality of first detection elements, calculating, based on the positional relationship, a shift amount for aligning the plurality of first detection elements with the multiple secondary electron beams, and moving, using the shift amount, the multi-detector relatively to the multiple secondary electron beams.