Multi-Beam Charged Particle Optics for Backscatter Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-beam inspection systems struggle with cross-talk issues when detecting backscattered charged particles, limiting their ability to effectively image structures below the surface and measure overlay targets due to the wide energy range and angle of emitted backscattered electrons.
Innovation Solution
A charged particle-optical device is designed with an objective lens array, up-beam and down-beam detector arrays, and a controller to manage potential application, enabling simultaneous detection of backscattered charged particles by positioning detectors proximate to the sample and controlling electron trajectories to reduce secondary particle interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If detectors are positioned to detect backscattered charged particles, then information about structures below the surface can be obtained, but cross-talk between adjacent beams occurs due to wide emission angles
Solution Approach 1:
The detection system is segmented into multiple independent detector elements arranged in an array, with each detector element corresponding to a specific beam position. This segmentation allows independent detection for each beam, preventing cross-talk between adjacent beams while maintaining the ability to detect backscattered particles from structures below the surface.
Solution Approach 2:
Each detector element is positioned at a specific location corresponding to its associated beam, creating localized detection zones. This local quality ensures that each detector only receives signals from its corresponding beam position, eliminating cross-talk while preserving subsurface structural information.
2Productivity
If multiple beams are used to increase inspection speed, then productivity is improved, but cross-talk issues arise when detecting backscattered particles
Solution Approach 1:
The system uses a segmented detector array where each detector element independently detects backscattered particles for its corresponding beam. This segmentation enables simultaneous operation of multiple beams without cross-talk interference, maintaining both high productivity and detection accuracy.
Solution Approach 2:
The detection system transitions from a single-point detector to a two-dimensional detector array, adding spatial dimensionality to the detection process. This dimensional expansion allows parallel detection for multiple beams, increasing throughput while maintaining reliability through spatial separation of detection zones.
3Measurement precision
If detectors are positioned close to the sample to detect backscattered electrons, then detection efficiency is improved, but secondary electron interference increases
Solution Approach 1:
Each detector element is positioned at a specific angle and location optimized for detecting backscattered electrons from its corresponding beam position. This localized positioning allows efficient backscattered electron detection while minimizing exposure to secondary electrons emitted at different angles, reducing interference.
Solution Approach 2:
The system uses electrostatic lenses or deflectors as intermediary elements between the sample and detectors to selectively guide backscattered electrons to the appropriate detector elements while deflecting secondary electrons away from the detection path, reducing interference.
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 device enhances throughput by accurately detecting backscattered electrons, allowing deeper inspection of buried defects and precise measurement of overlay targets, thereby improving the overall yield and efficiency of semiconductor manufacturing.
Implementation Method 1
an objective lens array configured to project the beams onto a sample and comprising at least two electrodes along primary beam paths of an array of beams of charged particles
Implementation Method 2
an up-beam array of detectors positioned up-beam of at least one electrode of the objective lens array along the primary beam paths; a down-beam array of detectors positioned down-beam of the at least one electrode of the objective lens array along the primary beam paths
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a various techniques for detecting secondary charged particles and backscatter charged particles, including accelerating charged particle sub-beams along sub-beam paths to a sample, repelling secondary charged particles from detector arrays, using mirror detector arrays, using multiple detector arrays, and providing devices and detectors which can switch between modes for primarily detecting charged particles and modes for primarily detecting secondary particles.