Charged Particle Beam Separator and Reflection Control for High-Speed Switching
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Solution Overview
Problem
In charged particle beam apparatuses, high-speed pulse formation leads to fluctuations in the electron beam's arrival position on the sample due to stray capacitance and inductance effects, causing unnecessary irradiation and potential charging and damage, while existing methods require large voltage changes that increase costs and reduce accuracy.
Innovation Solution
A charged particle beam apparatus incorporating a beam separator and an electron beam reflection control electrode, which deflects and reverses the electron beam's direction, allowing for high-speed and precise switching between irradiation and non-irradiation by applying small voltage changes, preventing position deviation and minimizing charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed pulse formation is performed using a deflector to switch between irradiation and non-irradiation, then productivity is improved, but manufacturing precision deteriorates due to arrival position fluctuation and overshoot/undershoot
Solution Approach 1:
The patent segments the beam switching function into two independent parts: a deflector for high-speed switching and a dedicated beam position correction unit. This segmentation allows the deflector to operate at high speed while the correction unit independently compensates for position deviations, resolving the contradiction between speed and precision.
Solution Approach 2:
The patent introduces a beam position correction unit as an intermediary component between the deflector and the sample. This intermediary actively compensates for the position deviations caused by the deflector's high-speed operation, enabling both high-speed switching and precise beam positioning to coexist.
2Reliability
If a large voltage change corresponding to acceleration voltage is applied to switch between irradiation and non-irradiation, then reliability is improved by preventing beam deflection, but device complexity increases and accuracy deteriorates
Solution Approach 1:
The patent changes the voltage parameter from large amplitude (corresponding to full acceleration voltage) to small amplitude adjustments. By using small voltage changes in the deflector and correction unit, the system achieves reliable beam switching without requiring complex high-voltage power supply devices, thus reducing device complexity while maintaining reliability.
3Object-generated harmful factors
If pulsed electron beam irradiation is used to prevent charging, then object-generated harmful factors are reduced, but manufacturing precision deteriorates due to position fluctuation during switching
Solution Approach 1:
The patent implements a feedback mechanism where the beam position correction unit continuously monitors and corrects the beam arrival position during pulsed irradiation. This feedback loop ensures that even during high-speed switching between irradiation and non-irradiation, the beam maintains accurate positioning, preventing both charging and position-related precision loss.
Solution Approach 2:
The beam position correction unit acts as an intermediary that decouples the harmful effects of pulsed switching from the precision requirements. It absorbs the position fluctuations inherent in pulsed operation and delivers a stable, precise beam to the sample, enabling pulsed irradiation without sacrificing 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 high-speed and high-precision electron beam switching without position deviation, reducing unnecessary irradiation and charging, thus enhancing inspection and measurement efficiency while maintaining accurate beam focus and reducing operational costs.
Implementation Method 1
the switch includes at least one electrode. The control device controls the switch such that a first voltage is applied to the electrode and a second voltage is applied to the electrode
Implementation Method 2
a charged particle beam reflection control electrode which absorbs and reflects a charged particle beam generated in the charged particle source by switching an applied voltage
Data Source
AI summary
A charged particle beam apparatus includes a charged particle source, a separator, a charged particle beam irradiation switch, and a control device. The separator is inserted into a charged particle optical system and deflects a traveling direction of a charged particle beam out of an optical axis of the charged particle optical system or deflects the traveling direction in the optical axis of the charged particle optical system. The charged particle beam irradiation switch absorbs the charged particle beam deflected out of the optical axis of the charged particle optical system or reflects the charged particle beam toward the separator. The control device controls a charged particle beam irradiation switch.