Multi-Beam Generating Unit Shielding and Cooling for Drift Control
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Solution Overview
Problem
Multi-beam charged particle microscopes face challenges with drifts in performance due to thermal and charging effects, leading to reduced imaging resolution and increased risk of damage from secondary radiation, particularly x-rays, which affect the micro-electronic devices controlling the multi-aperture elements.
Innovation Solution
The implementation of a multi-beam generating unit with an active multi-aperture element and a control unit, featuring a shielding member and cooling member to minimize the impact of secondary radiation and thermal drifts, along with annealing methods to extend the lifetime of the active multi-aperture elements and voltage supply units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-aperture element is used to generate multiple beamlets, then productivity is improved through parallel scanning, but the system becomes sensitive to drifts and thermal effects that degrade measurement precision
Solution Approach 1:
The voltage supply system is segmented into multiple independent voltage supply units, each controlling a specific group of electrodes. This segmentation allows independent compensation of drifts for different parts of the multi-aperture element, maintaining imaging resolution while preserving parallel scanning capability
Solution Approach 2:
A feedback mechanism is implemented where drifts in voltage supply units are monitored and compensated by adjusting other voltage supply units. The control unit receives information about drifts and automatically adjusts voltages to maintain stable beamlet positions, resolving the contradiction between productivity and measurement precision
2Device complexity
If micro-electronic devices are placed close to multi-aperture elements for control, then device complexity is reduced, but reliability decreases due to damage from secondary radiation
Solution Approach 1:
A shielding member is introduced as an intermediary between the multi-aperture element and the voltage supply units. This shielding structure protects the micro-electronic devices from secondary radiation while allowing necessary electrical connections, thus maintaining reliability without significantly increasing device complexity
Solution Approach 2:
The voltage supply units are designed to be replaceable and can be recalibrated or replaced when damaged by radiation. This approach accepts that these components have limited lifetime due to radiation exposure but maintains system reliability through easy replacement rather than attempting to make them radiation-hardened
3Stability of the object's composition
If voltage supply units operate continuously to maintain beamlet stability, then stability of the object's composition is improved, but thermal effects increase causing drifts that worsen measurement precision
Solution Approach 1:
The system dynamically adjusts voltage parameters to compensate for thermal drifts. When thermal effects cause drifts, the control unit modifies the voltage parameters supplied to different voltage supply units to maintain stable beamlet positions, resolving the contradiction between continuous operation stability and measurement 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
This solution enhances the imaging performance by reducing the sensitivity to drifts and thermal loads, extending the lifetime of the multi-beam system, and minimizing damage from x-ray irradiation, thereby improving the overall operational stability and maintenance requirements of the microscope.
Implementation Method 1
shielding member... to shield secondary radiation from hitting the voltage supply unit
Implementation Method 2
cooling member to minimize the impact of secondary radiation and thermal drifts
Implementation Method 3
annealing methods to extend the lifetime of the active multi-aperture elements and voltage supply units
Data Source
AI summary
A multi-beam generating unit of a multi-beam charged particle imaging system can exhibit reduced sensitivity to drift and extended lifetime. Drifts due to x-ray irradiation and thermal loads can be minimized by a combination of at least one of a shielding element, a cooling member, or an architecture and method for operating an active multi-aperture element. A lifetime can be improved by annealing methods of an active multi-aperture element or a microelectronic device forming for example a voltage supply unit.