Emitter Flash Cleaning Feedback Loop Stabilization
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Solution Overview
Problem
Charged particle beam devices experience fluctuations in emission current due to adsorption of residual gas molecules and shape changes during flash cleaning, leading to destabilization of the emitter and quality degradation of the charged particle beam.
Innovation Solution
A method and device that utilize a feedback loop system to adjust the electric field during flash cleaning, determining optimal voltage values based on the emission current to stabilize the emitter shape and maintain consistent emission current, incorporating a voltage generating system and measurement unit to control voltages during flash cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flash cleaning is performed periodically to remove adsorbed molecules, then the emission current stability is improved, but the emitter shape changes causing new fluctuations in emission current
Solution Approach 1:
The patent implements a feedback loop that continuously monitors the emission current and adjusts the electric field strength during flash cleaning operations. The measurement unit detects emission current values, and the control unit modifies the electric field accordingly to compensate for emitter shape changes, thereby maintaining emission current stability despite repeated flash cleaning
Solution Approach 2:
The patent dynamically changes the electric field strength parameter during flash cleaning based on the monitored emission current. By adjusting this physical parameter in real-time, the system compensates for emitter shape changes and maintains stable emission current without requiring fixed electric field conditions
2Productivity
If the electric field strength is increased during flash cleaning to remove adsorbed molecules, then the cleaning effectiveness is improved, but the emitter shape changes more significantly
Solution Approach 1:
The feedback mechanism monitors emission current changes that indicate emitter shape modification and adjusts the electric field strength accordingly. This prevents excessive electric field application that would cause significant shape changes, while still maintaining sufficient cleaning effectiveness
Solution Approach 2:
The patent transitions from static electric field application to dynamic adjustment of electric field strength during flash cleaning. The electric field is continuously adapted based on real-time emission current measurements, allowing optimal balance between cleaning effectiveness and emitter shape preservation
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 effectively stabilizes the emission current by adjusting the electric field during flash cleaning, preventing emitter shape changes and maintaining long-term stability of the charged particle beam quality.
Implementation Method 1
the emitter is a cold field emitter with an emitter tip
Implementation Method 2
the emitter can be subjected to flash cleaning. Flash cleaning is typically done by shortly heating the emitter to a high temperature, e.g. 2000 K, such that the adsorbed molecules are desorbed
Implementation Method 3
a first electric field is applied to the emitter. The first electric field is generated by the at least one voltage having a first value
Data Source
AI summary
A method and a device for stabilizing the emission current of an emitter of a charged particle beam device are provided. In the method, the emitter is operated under predetermined operation parameters including at least one voltage with a predetermined value. The method includes determining a first value of the emission current under the predetermined operation parameters and flash cleaning the emitter while a first electric field is applied to the emitter. The first electric field is generated by the at least one voltage having a first value of the at least one voltage, wherein the first value of the at least one voltage is provided in dependence of the determined first value of the emission current.