Optical Emitter Tip Cleaning for Stable Electron Beam Sources
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Solution Overview
Problem
Existing methods for cleaning electron sources in charged-particle beam systems, such as field-emission sources, face challenges in maintaining imaging resolution and inspection throughput due to contamination, which often require shutdowns and result in reduced electron source longevity and increased outgassing, leading to inefficient vacuum conditions.
Innovation Solution
An electron beam apparatus comprising an electron source and an optical source, where the optical source generates a focused optical beam to illuminate the emitter tip, exciting a surface mode that facilitates the removal of contaminants without significant heat generation, thereby maintaining vacuum integrity and extending the electron source's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If existing cleaning methods are used to remove contaminants from electron emitter tips, then contaminant removal is achieved, but electron source longevity is reduced and outgassing increases
Solution Approach 1:
The patent replaces thermal/mechanical cleaning methods with optical field-based cleaning. An optical source generates an optical field that interacts with contaminants on the emitter tip surface, removing them through optical forces rather than thermal heating or mechanical contact, thereby extending electron source longevity while maintaining cleaning effectiveness
Solution Approach 2:
The patent changes the physical state and interaction parameters by using optical field parameters (intensity, frequency, wavelength) to control the cleaning process. By adjusting optical field parameters, contaminants are removed through optical pressure and resonance effects rather than thermal parameters, reducing damage to the electron source
2Object-generated harmful factors
If existing cleaning methods are used to remove contaminants from electron emitter tips, then contaminant removal is achieved, but vacuum conditions deteriorate due to increased outgassing
Solution Approach 1:
The patent replaces thermal cleaning methods that cause outgassing with optical field-based cleaning. The optical field removes contaminants through non-thermal mechanisms, preventing the heating-induced outgassing that would deteriorate vacuum conditions in the electron beam apparatus
Solution Approach 2:
The optical field acts as an intermediary between the cleaning process and the electron source. It transfers energy to remove contaminants without directly heating the electron source or surrounding vacuum environment, thus maintaining vacuum integrity while achieving effective contaminant removal
3Stability of the object's composition
If existing cleaning methods are used to maintain electron source stability, then emission current stability is improved, but inspection throughput decreases due to shutdown requirements
Solution Approach 1:
The patent enables continuous cleaning action by using optical fields that can operate without interrupting the electron beam operation. The optical source continuously removes contaminants from the emitter tip surface during inspection, maintaining emission current stability without requiring shutdowns, thereby preserving inspection throughput
Solution Approach 2:
The optical cleaning system performs preliminary and continuous contaminant removal before contaminants can significantly degrade emission current stability. This preventive approach maintains stable electron emission throughout the inspection process without requiring interruptive cleaning cycles
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 approach allows for efficient contaminant removal with minimal outgassing, maintaining high emission current stability, extending the electron source's operational time, and enhancing inspection throughput without the need for frequent tool shutdowns.
Implementation Method 1
The optical source may be configured to generate an optical beam illuminating a portion of the emitter tip to excite a surface mode of the optical beam, wherein the excited surface mode facilitates removal of a contaminant from a surface of the illuminated portion of the emitter tip
Implementation Method 2
The optical source may be configured to generate an optical beam illuminating a portion of the emitter tip to remove a contaminant from a surface of the illuminated portion of the emitter tip
Data Source
AI summary
Systems and methods of removing a contaminant from an emitter tip of an electron source in an electron beam apparatus are disclosed. An electron beam apparatus may include an electron source comprising an emitter tip configured to emit electrons and an optical source configured to generate an optical beam illuminating a portion of the emitter tip to excite a surface mode of the optical beam, wherein the excited surface mode facilitates removal of a contaminant from a surface of the illuminated portion of the emitter tip. The excited surface mode may comprise a propagating surface wave or a localized surface wave. The emitter tip may comprise a grating structure, wherein a characteristic of the grating structure matches a wavevector of the optical beam.