Second Objective Lens Design for Simultaneous SEM Operation
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Solution Overview
Problem
Conventional scanning electron microscopes (SEMs) face limitations in achieving high-resolution observations simultaneously with both first and second objective lenses, as they are typically switched between modes and lack the capability for simultaneous operation, affecting performance and flexibility in sample analysis.
Innovation Solution
The design allows for independent control and simultaneous operation of both the first and second objective lenses, with the second objective lens having a magnetic flux density distribution that is higher closer to the sample, enabling improved focusing and detection of secondary electrons, and the use of a retarding voltage to decelerate primary electrons for enhanced resolution and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the first objective lens and the second objective lens are switched by mode switching means, then the device can operate in different observation modes, but the lenses cannot operate simultaneously reducing flexibility and performance
Solution Approach 1:
The patent implements dynamic control of the objective lenses by introducing a switching mechanism that can dynamically select between different operational modes (first objective lens mode, second objective lens mode, or combined mode) based on observation requirements. This dynamic switching capability resolves the contradiction by allowing the system to adapt its configuration in real-time rather than being fixed in a single mode.
Solution Approach 2:
The patent creates a multi-functional objective lens system where both the first and second objective lenses can be used independently or in combination. The universal design allows the same lens assembly to serve multiple functions: high-resolution imaging with the second lens, broader observation with the first lens, or combined operation for enhanced performance, thereby simultaneously improving adaptability and productivity.
2Measurement precision
If the magnetic flux density of the lens is increased for higher resolution, then the resolution improves, but the lens thickness must be decreased which complicates the lens structure
Solution Approach 1:
The patent segments the objective lens into multiple functional components with distinct magnetic pole arrangements. By dividing the lens structure into separate magnetic pole pieces that can be independently configured, the system achieves high magnetic flux density in specific regions without requiring the entire lens to be thin, thus resolving the contradiction between resolution and structural complexity.
Solution Approach 2:
The patent applies local quality by creating regions of high magnetic flux density only where needed for resolution enhancement, rather than uniformly increasing flux density throughout the entire lens. The magnetic pole pieces are strategically positioned to concentrate magnetic fields in specific areas, achieving high resolution without requiring overall lens thinning that would increase structural complexity.
3Measurement precision
If the second objective lens is used for high-resolution observation at low accelerating voltage, then resolution improves, but the lens must be separated from the sample with an electric insulator which complicates the setup
Solution Approach 1:
The patent introduces an electric insulator as an intermediary element between the second objective lens and the sample. This intermediary component serves multiple functions: it provides the necessary electrical isolation to apply decelerating voltage while maintaining mechanical proximity for high-resolution imaging. The insulator is integrated into the lens assembly design, minimizing its impact on overall structure and avoiding excessive complexity.
4Measurement precision
If a retarding voltage is applied to decelerate primary electrons, then secondary electron detection sensitivity improves, but the system requires additional voltage control mechanisms increasing device complexity
Solution Approach 1:
The patent merges the voltage control function into the existing objective lens power supply system. By combining the retarding voltage control with the objective lens excitation control, the system achieves secondary electron detection enhancement without requiring completely separate voltage control mechanisms. The power supply unit is configured to provide both functions through integrated control, reducing overall device complexity.
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
This configuration enables high-resolution imaging with improved sensitivity and flexibility, allowing for better detection of secondary electrons and reduced aberration, thereby enhancing the overall performance of the SEM.
Implementation Method 1
the second objective lens having a magnetic flux density distribution that is higher closer to the sample
Implementation Method 2
the use of a retarding voltage to decelerate primary electrons for enhanced resolution and sensitivity
Implementation Method 3
lenses that are each configured to have a short focus for a higher resolution. Increasing resolution requires increasing the magnetic flux density for the magnetic flux density distribution B(z) of the lens along the optical axis
Data Source
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AI summary
A charged particle beam device includes: a charged particle source configured to emit a charged particle beam(12); an acceleration electric power source connected to the charged particle source and configured to accelerate the charged particle beam (12); a second objective lens (26) configured to focus the charged particle beam (12) onto a sample (23); and a second detector (110). The second objective lens (26) is positioned on the opposite side of the sample (23) from where the charged particle beam (12) is incident on the sample (23). The second detector (110) is configured to receive at least one of (i) an electromagnetic wave that the sample (23) emits upon receiving the charged particle beam (12) and (ii) an electromagnetic wave that the sample (23) reflects upon receiving the charged particle beam (12). The second detector (110) carries out a detection of the received electromagnetic wave(s).