Multi-column SEM with Bonded Electron-Optical Columns
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Solution Overview
Problem
Current scanning electron microscopy (SEM) systems face challenges such as reduced resolution, speed, and throughput due to beam splitting, scalability issues, crosstalk between electron detectors, and limitations in miniaturizing electron-optical columns, which affect the inspection and review of semiconductor wafers and photomasks.
Innovation Solution
A multi-column scanning electron microscopy system is developed, featuring a source assembly with multiple electron beam sources and positioners, and a column assembly with substrate arrays and bonded electron-optical columns, allowing for individualized electron beam tuning and positioning, reduced crosstalk, and improved scan control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single electron beam is split into numerous beams for multi-beam SEM inspection, then the inspection area coverage is improved, but the resolution deteriorates due to global tuning limitations and reduced beam current
Solution Approach 1:
The patent divides the inspection system into multiple independent electron-optical columns, each handling a specific field of view. Instead of splitting one beam globally, multiple beams are generated independently and assigned to separate columns that can be individually tuned and optimized, thereby maintaining high resolution while covering large inspection areas.
Solution Approach 2:
The patent transitions from a single-column architecture to a multi-column array architecture, adding spatial dimensionality to the system. This allows parallel processing of multiple fields of view simultaneously, expanding the inspectable area without compromising the resolution capabilities of individual columns.
2Area of stationary object
If a single electron beam is split into N beams for multi-beam inspection, then the inspection area is expanded, but the scan speed and throughput reduce due to requiring more scans and averages
Solution Approach 1:
The inspection task is segmented across multiple independent electron-optical columns, each capable of autonomous scanning and imaging. This parallel architecture eliminates the need for multiple sequential scans and averages required by single-beam splitting systems, thereby maintaining high scan speed and throughput while expanding inspection area.
Solution Approach 2:
Multiple electron-optical columns operate simultaneously and continuously, each independently scanning and imaging its assigned field of view. This parallel continuous operation eliminates the sequential scanning requirements of multi-beam systems, maintaining high productivity while expanding the total inspection area.
3Adaptability or versatility
If the number of electron-optical columns is increased for better inspection coverage, then the inspection capability is improved, but device complexity and scalability issues arise due to field curvature and transverse aberrations
Solution Approach 1:
The system is divided into multiple standardized, modular electron-optical columns that can be independently designed, manufactured, and tuned. Each column is a self-contained unit with standardized interfaces, allowing scalable assembly without compounding complexity. This modular segmentation enables easy system expansion while maintaining consistent performance across all columns.
Solution Approach 2:
The patent employs standardized electron-optical column designs that can be universally applied and replicated across the array. Each column serves multiple functions (beam generation, focusing, scanning, detection) and can be independently optimized, allowing the system to scale without proportionally increasing overall complexity.
4Reliability
If individual stacks of metal, ceramic rings, and electromagnets are used for electron-optical columns, then the column functionality is achieved, but the size becomes too large for ideal pitch optimization and significant packing density
Solution Approach 1:
The patent integrates multiple electron-optical column components into nested or stacked compact arrangements. By nesting functional elements within each other and using shared substrates, the physical footprint of each column is dramatically reduced, enabling ideal pitch optimization and high packing density while maintaining full column functionality.
Solution Approach 2:
Adjacent electron-optical columns share common substrates, support structures, and control electronics. This merging of functional elements between columns reduces the overall system size and enables closer spacing, achieving ideal pitch optimization and high packing density without sacrificing individual column performance.
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 system enhances resolution, speed, and throughput by enabling individualized electron beam control, reducing crosstalk, and optimizing the packing density of electron-optical columns, thereby improving the inspection and review processes for semiconductor devices.
Implementation Method 1
two or more electron beam sources configured to generate a plurality of electron beams
Implementation Method 2
two or more electron-optical columns... configured to direct at least a portion of an electron beam
Data Source
AI summary
A multi-column scanning electron microscopy (SEM) system is disclosed. The SEM system includes a source assembly. The source assembly includes two or more electron beam sources configured to generate a plurality of electron beams. The source assembly also includes two or more sets of positioners configured to actuate the two or more electron beam sources. The SEM system also includes a column assembly. The column assembly includes a plurality of substrate arrays. The column assembly also includes two or more electron-optical columns formed by a set of column electron-optical elements bonded to the plurality of substrate arrays. The SEM system also includes a stage configured to secure a sample that at least one of emits or scatters electrons in response to the plurality of electron beams directed by the two or more electron-optical columns to the sample.