Charged Particle Beam Device Low-Noise Blanking Control
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Solution Overview
Problem
The existing charged particle beam devices face a decline in measurement accuracy due to noise-induced electron beam deflection when the blanking control circuit is OFF, primarily caused by power supply and GND noise, which is challenging to mitigate with existing two-stage blanking electrode configurations.
Innovation Solution
A charged particle beam device with a low-noise blanking control circuit design that includes a configuration of switching circuits and MOSFETs to manage noise voltages, ensuring equal amplitude and phase noise application to both blanking electrodes when the control signal is OFF, preventing electric field generation and improving deflection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a two-stage blanking electrode configuration is used to reduce noise, then noise electric fields are offset, but the upper and lower electrodes have different deflection sensitivities making noise voltage adjustment difficult
Solution Approach 1:
The patent applies equipotentiality by connecting corresponding blanking electrodes (upper and lower) to the same potential through the switching circuit configuration. When the blanking control signal is OFF, all four switching circuits are turned ON, connecting both upper and lower electrodes to the same reference potential (either GND or power supply voltage), ensuring they experience identical noise voltages and maintain equal deflection sensitivity without requiring separate adjustment mechanisms.
2Measurement precision
If noise reduction filters are added to mitigate power supply and GND noise, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent converts the harmful effect of noise into a beneficial configuration by designing the switching circuit so that when blanking is OFF, both upper and lower electrodes receive identical noise voltages from the power supply or GND. This transforms the noise from a differential disturbance (harmful) into a common-mode signal that produces equal and opposite deflections, canceling out the net effect on beam position while eliminating the need for additional filter circuits.
3Productivity
If the blanking control circuit is turned OFF to allow electron beam passage, then beam transmission is enabled, but noise-induced electron beam deflection occurs reducing measurement accuracy
Solution Approach 1:
The patent employs asymmetry in the spatial arrangement and control of the blanking electrodes. The upper and lower electrodes are positioned asymmetrically relative to the electron beam path, and the switching circuit controls them in a coordinated asymmetric manner - turning ON specific switching circuits to connect electrodes to different potentials. This asymmetric configuration enables the electrodes to generate compensating deflection fields that counteract noise-induced deflections while maintaining efficient beam transmission when blanking is OFF.
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 design enhances measurement accuracy by eliminating noise-induced electron beam deflection, allowing for improved sensitivity and response speed without the need for additional noise reduction filters, thus improving the overall performance of the charged particle beam device.
Implementation Method 1
a first blanking electrode connected to the first switching circuit and the second switching circuit; a second blanking electrode facing the first blanking electrode
Implementation Method 2
there is a problem that the electron beam is emitted in an unintended direction and a decline in measurement accuracy arises
Data Source
AI summary
Provided is a charged particle beam device with low blanking noise and improved signal detection accuracy. As means therefor, a charged particle beam device is configured by: a stage where a sample is mountable; a charged particle gun performing charged particle emission to the sample; a voltage source; a first switching circuit to which a voltage is supplied from the voltage source; a second switching circuit having one end connected to a ground; a third switching circuit having one end connected to the ground; a fourth switching circuit to which a voltage is supplied from the voltage source; a first blanking electrode connected to the first switching circuit and the second switching circuit; a second blanking electrode facing the first blanking electrode and connected to the third switching circuit and the fourth switching circuit; and a control circuit controlling the first switching circuit, the second switching circuit, the third switching circuit, and the fourth switching circuit.