Objective Lens Configuration for Simultaneous Dual-Lens SEM Operation
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Solution Overview
Problem
Conventional scanning electron microscopes (SEMs) face limitations in achieving high resolution due to the inability to operate both first and second objective lenses simultaneously, which restricts the device's performance and imaging capabilities.
Innovation Solution
A charged particle beam device is designed with a unique objective lens configuration, including a central magnetic pole, an upper magnetic pole, and a disk-shaped lower magnetic pole, allowing for simultaneous operation of both lenses and improved focusing capabilities, along with an insulating sheet and electrically conductive sample stage to manage electric potential and prevent electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both first and second objective lenses are operated simultaneously, then imaging performance and resolution are improved, but device complexity increases
Solution Approach 1:
The objective lens system is divided into two distinct lenses: a first objective lens for normal observation mode and a second objective lens for high-resolution observation mode. Each lens is independently controllable, allowing selective operation based on imaging requirements. The second objective lens is positioned closer to the sample than the first objective lens, enabling simultaneous operation without interference.
Solution Approach 2:
The patent introduces a new spatial dimension by placing the second objective lens in front of the first objective lens (closer to the sample). This multi-layer lens arrangement along the optical axis enables both lenses to function simultaneously, with the second lens providing high-resolution focusing and the first lens providing broader observation capability.
2Measurement precision
If the second objective lens is used for high-resolution observation, then resolution is improved, but the accelerating voltage must be limited to low range
Solution Approach 1:
The system dynamically switches between different lens configurations based on observation requirements. The second objective lens is specifically designed for low accelerating voltage operation (0.5-5 kV) to achieve high resolution, while the first objective lens handles normal voltage ranges (0.5-30 kV). The system can adaptively select which lens to use based on the required resolution and voltage conditions.
3Ease of operation
If magnetic poles are separated with electric insulator, then electrical control is improved, but device complexity increases
Solution Approach 1:
An electric insulator is introduced as an intermediary component between the magnetic poles of the second objective lens. This insulator enables independent electrical control of different magnetic pole groups, allowing separate adjustment of magnetic fields for different functional regions of the lens while maintaining structural integrity.
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 enhanced performance and high-resolution imaging by allowing independent control of both objective lenses, improving the focusing and detection of secondary and backscattered electrons, thereby increasing the SEM's operational efficiency.
Implementation Method 1
an acceleration electric power source connected to the charged particle source and configured to accelerate a charged particle beam emitted by the charged particle source
Implementation Method 2
an objective lens configured to focus the charged particle beam onto a sample, the objective lens including: a central magnetic pole having a central axis coinciding with an ideal optical axis of the charged particle beam; an upper magnetic pole; a cylindrical side-surface magnetic pole; and a disk-shaped lower magnetic pole
Data Source
AI summary
A charged particle beam device includes: a charged particle source; an acceleration electric power source connected to the charged particle source for accelerating a charged particle beam emitted by the acceleration electric power source; and an objective lens for focusing the charged particle beam onto a sample, the objective lens including: a central magnetic pole having a central axis coinciding with an ideal optical axis of the charged particle beam; an upper magnetic pole; a cylindrical side-surface magnetic pole; and a disk-shaped lower magnetic pole, the central magnetic pole having an upper portion on a side of the sample and a column-shaped lower portion, the upper magnetic pole having a circular opening at a center thereof and being in a shape of a disk that is tapered to a center thereof and that is thinner at a position closer to a center of gravity of the central magnetic pole.