Confocal Electron Detection for 3D Semiconductor SEM Imaging
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Solution Overview
Problem
Conventional SEMs struggle to provide high-throughput, non-destructive 3D structural measurement of miniaturized semiconductor structures, failing to meet the demands of high-resolution defect inspection and yield improvement due to limitations in resolution and depth sectioning capabilities.
Innovation Solution
A reflectance confocal scanning electron microscope (RCSEM) with a first column device for electron beam incidence and a second column device for de-scanning, combined with an objective lens, spatial filter, and detector, enables confocal detection and depth sectioning, enhancing resolution and contrast through confocal filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SEM is used for surface observation, then basic imaging is achieved, but resolution and depth sectioning capabilities are insufficient for miniaturized semiconductor structures
Solution Approach 1:
The SEM system is divided into two independent column devices: a first column device for electron beam generation and scanning, and a second column device for electron detection. This segmentation allows each column to be optimized independently, with the second column incorporating confocal filtering components to achieve high-resolution depth sectioning without compromising the overall system's manageability
Solution Approach 2:
The patent introduces a vertical dimension to electron beam detection by implementing confocal filtering in the second column device. The pinhole aperture is positioned at a specific focal plane conjugate to the sample surface, enabling depth sectioning capability that filters electrons based on their origin depth, thereby adding axial resolution to the traditionally two-dimensional imaging process
2Measurement precision
If conventional SEM imaging is performed, then surface structure is visible, but high-contrast imaging and depth sectioning are not achieved
Solution Approach 1:
The detection system is separated into a distinct second column device that incorporates confocal filtering components (objective lens, pinhole aperture, and detector) independent from the electron beam generation and scanning system. This allows the confocal detection path to be optimized specifically for depth sectioning without affecting the scanning capabilities
Solution Approach 2:
A pinhole aperture is introduced as an intermediary element in the electron detection path. This pinhole is positioned at a focal plane conjugate to the sample surface, acting as a spatial filter that only allows electrons originating from the focal plane to reach the detector, thereby achieving optical sectioning and high-contrast imaging of specific depths
3Productivity
If miniaturized semiconductor structures are inspected, then high-resolution defect detection is needed, but conventional SEM lacks sufficient throughput and non-destructive measurement capability
Solution Approach 1:
The patent replaces conventional optical filtering methods with electron beam-based confocal filtering. By using electromagnetic lenses and electron optics in the second column device, the system achieves high-resolution depth sectioning capable of inspecting miniaturized semiconductor structures with sub-micron precision while maintaining inspection throughput through efficient electron detection
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 RCSEM achieves high-contrast imaging, improves resolution by 40% in lateral and 7 times in vertical directions, supports 3D structural measurement, and enables non-destructive inspection of semiconductor structures, overcoming the limitations of conventional SEMs.
Implementation Method 1
The electron beam possesses concentrated high energy and interacts with the sample surface to acquire various information
Implementation Method 2
scans the sample with an electron beam and generates images... scans the electron beam onto the sample surface to generate electron signals on the surface
Implementation Method 3
an objective lens configured to focus electrons scattered from a sample
Implementation Method 4
a spatial filter configured to confocally filter an electron beam focused through the objective lens
Implementation Method 5
a second column device configured to de-scan the electron beam after it is reflected from the sample to confocally detect electrons emitted from the sample
Data Source
AI summary
A reflectance confocal scanning electron microscope according to of the present inventive concept may include, a first column device configured to allow an electron beam to be incident on a sample, and a second column device configured to de-scan the electron beam after it is reflected from the sample to confocally detect electrons emitted from the sample.