Cold Field Emitter Heating Control via Auxiliary Electrode Current
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Solution Overview
Problem
Existing charged particle beam devices fail to accurately manage the temperature of cold field emitters during cleaning treatments, leading to potential damage and instability in electron emission.
Innovation Solution
A charged particle beam device with an auxiliary electrode that collects thermionic electrons emitted during heating, allowing precise temperature management by measuring current through the auxiliary electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a negative voltage is applied to the suppression electrode to prevent thermionic electron emission during cleaning treatment, then the harmful effects of thermionic electrons are reduced, but the temperature management precision deteriorates because the temperature cannot be accurately estimated when emission is suppressed
Solution Approach 1:
The patent introduces a current detection electrode as an intermediary component that indirectly measures the temperature of the cold field emitter during cleaning treatment. Instead of directly observing thermionic electron emission (which is suppressed by negative voltage), the detection electrode measures the current generated by thermionic electrons that do escape through the opening, providing an indirect but accurate temperature indicator without compromising the suppression of harmful electron emission
Solution Approach 2:
The patent implements a feedback mechanism where the current detected by the current detection electrode is used to monitor and control the temperature of the cold field emitter during cleaning treatment. The detected current signal is fed back to the control system, which adjusts the heating conditions to maintain optimal temperature, ensuring both effective cleaning and prevention of thermionic electron damage
2Manufacturing precision
If the tip is sharpened to high spatial resolution, then the electron beam quality is improved, but the tip becomes more susceptible to contamination from residual gas adhesion
Solution Approach 1:
The patent implements periodic cleaning treatment by applying heating pulses to the cold field emitter at regular intervals. This periodic heating removes accumulated residual gas contamination from the sharpened tip surface, restoring the emission current stability and maintaining high spatial resolution over extended operation periods
Solution Approach 2:
The patent changes the temperature parameter of the cold field emitter during cleaning treatment by applying heating pulses that temporarily raise the tip temperature. This temperature change enables the removal of adsorbed residual gas molecules without permanent damage to the sharpened tip structure, thereby maintaining both high resolution and emission stability
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
Precise temperature control during cleaning treatments extends the life of the cold field emitter and improves the reproducibility of observation images while reducing downtime and costs.
Implementation Method 1
When the tip and the filament are heated, thermionic electrons emitted from the tip and the filament are collected in the auxiliary electrode
Implementation Method 2
to measure a current by applying a positive voltage with respect to the tip to the auxiliary electrode
Data Source
AI summary
Provided is a charged particle beam device that can precisely manage a temperature at which a cold field emitter is heated. A charged particle beam device includes: a cold field emitter including a tip having a sharpened distal end, a filament connected to the tip, and an auxiliary electrode covering the filament and having an opening from which the tip protrudes; an extraction electrode to which an extraction voltage for extracting electrons from the cold field emitter is applied; and an acceleration electrode to which an acceleration voltage for accelerating the electrons extracted from the cold field emitter is applied. When the tip and the filament are heated, thermionic electrons emitted from the tip and the filament are collected by the auxiliary electrode to measure a current by applying a positive voltage with respect to the tip to the auxiliary electrode.