Movable Condenser Lens for Electron Beam Alignment
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Solution Overview
Problem
Existing electron beam systems face challenges in achieving high brightness and low aberrations while maintaining good alignment, particularly with cold field emitter sources which require sophisticated operation methods and stringent vacuum conditions, limiting their industrial application.
Innovation Solution
A movable condenser lens arrangement using magnetic deflectors to adjust the optical axis relative to the symmetry axis, allowing for precise alignment and emission stability, thereby achieving high brightness and small spot size with reduced aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a cold field emitter source is used to achieve high brightness, then the electron beam brightness is improved, but the system requires stringent vacuum conditions and sophisticated operation methods
Solution Approach 1:
A movable condenser lens is introduced as an intermediary component between the cold field emitter and the objective lens. This lens can be dynamically repositioned along the optical axis to compensate for alignment deviations caused by vacuum fluctuations or thermal effects, thereby maintaining stable beam alignment without compromising the high brightness provided by the cold field emitter
Solution Approach 2:
The condenser lens is designed with dynamic positioning capability, allowing it to move along the optical axis in response to changing vacuum conditions or beam alignment requirements. This dynamic adjustment mechanism enables the system to maintain optimal alignment stability while preserving the high brightness characteristics of the cold field emitter source
2Area of moving object
If the condenser lens is positioned close to the emitter to achieve small spot size, then the spot size is reduced, but the alignment between beam axis and lens symmetry axis becomes more difficult to maintain
Solution Approach 1:
The condenser lens is made dynamically adjustable along the optical axis, enabling real-time compensation for alignment deviations. This dynamic positioning capability allows the lens to maintain precise alignment with the beam axis even when positioned close to the emitter for minimal spot size
Solution Approach 2:
The system incorporates feedback mechanisms to detect alignment deviations between the beam axis and lens symmetry axis. Based on this feedback, the movable condenser lens is automatically repositioned to correct alignment errors, thereby maintaining manufacturing precision while achieving small spot size
3Productivity
If high probe current is used to improve productivity, then the productivity is increased, but the aberrations in the electron beam increase
Solution Approach 1:
The movable condenser lens enables dynamic optimization of the beam parameters. By adjusting the lens position along the optical axis, the system can maintain low aberrations even when operating at high probe currents, thereby decoupling the trade-off between productivity and beam quality
Solution Approach 2:
The system utilizes parameter changes in the condenser lens positioning to optimize beam characteristics. By varying the lens position parameter, the system can achieve high probe current with minimal aberration, effectively resolving the contradiction between productivity and manufacturing precision
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 solution enables stable and high-brightness electron beam emission with improved alignment and reduced aberrations, overcoming the limitations of cold field emitter sources and enhancing the performance of electron beam systems.
Implementation Method 1
The deflector (722) is adapted to generate a magnetic field for moving the optical axis (730) of the condenser lens arrangement (720) with respect to the symmetry axis (725) of the condenser lens (721)
Implementation Method 2
a condenser lens (721) having a symmetry axis (725), wherein the beam emitter axis (735) is displaced with respect to the symmetry axis (725) of the condenser lens (721)
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
A condenser lens arrangement (320; 420; 600; 720) for an electron beam system is described. The condenser lens arrangement includes a magnetic condenser lens (321; 42; 610; 721) adapted for generating a magnetic condenser lens field, the condenser lens having a symmetry axis (450; 725), and a magnetic deflector (322; 422; 500) adapted for generating a magnetic deflector field. The deflector is configured so that the superposition of the magnetic condenser lens field and the magnetic deflector field results in an optical axis (730) of the condenser lens arrangement being movable relative to the symmetry axis (450; 725). Further, an electron beam optical system including a condenser lens arrangement (700) and a method (800; 900) for moving a condenser lens are described.