Cold Field Emitter Tip Segmentation for Stable Electron Beam
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Solution Overview
Problem
Existing electron beam devices face challenges in achieving high brightness and stability due to the limitations of Schottky sources, which are sensitive to environmental factors and have unstable emission, particularly in applications requiring high resolution and throughput.
Innovation Solution
A cold-field emitter with a crystalline emitter tip having multiple adjacent facets and an intermediate area configured for electron emission, where the facets are separated and the intermediate area is smooth, allowing for stable and efficient electron emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Schottky sources are used to provide high emission current, then the throughput is improved, but the emission stability deteriorates due to sensitivity to environmental factors
Solution Approach 1:
The emitter tip surface is divided into multiple adjacent facets (first facet, second facet, third facet, fourth facet) that are separated from each other. This segmentation creates distinct emission regions while isolating them from environmental bombardment, allowing high current extraction through multiple separated areas rather than a single continuous surface.
Solution Approach 2:
Different regions of the emitter tip are given different properties: the facets are configured to emit electrons when subjected to a strong electric field, while the intermediate areas between facets provide structural separation and additional emission pathways. Each facet can be optimized independently for specific emission characteristics.
2Illumination intensity
If cold field emission is used to achieve high brightness, then the brightness is improved, but the emission stability deteriorates due to sensitivity to residual gas molecules
Solution Approach 1:
The emitter tip is pre-shaped with multiple facets and intermediate areas before operation. This preliminary structuring creates a configuration that inherently resists environmental degradation, allowing the cold field emission process to maintain stability over extended periods without requiring frequent reconditioning or replacement.
Solution Approach 2:
The emitter operates based on quantum tunneling through the potential barrier at the metallic specimen surface, utilizing the strong electric field effect rather than thermal emission. This parameter change from thermal to field-driven emission enables high brightness while reducing sensitivity to environmental factors such as residual gas molecules.
3Quantity of substance
If the emitter tip surface is made continuous to maximize emission area, then the emission current is improved, but the lifespan deteriorates due to increased sensitivity to environmental bombardment
Solution Approach 1:
The emitter tip surface is divided into multiple adjacent facets (first facet, second facet, third facet, fourth facet) that are separated from each other. This segmentation creates distinct emission regions while isolating them from environmental bombardment, allowing high current extraction through multiple separated areas rather than a single continuous surface.
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 provides a stable and high-brightness electron beam emission with a longer lifespan, suitable for applications like automated wafer inspection, reducing maintenance and operational costs by enhancing emission stability and throughput.
Implementation Method 1
Theoretically, a higher brightness can be achieved by a source based on cold field emission and a tunneling effect through the potential barrier on the usually metallic specimen surface
Implementation Method 2
Cold-field emitters do not use high temperatures for operation and the brightness is higher
Implementation Method 3
The electron beam source further includes an extractor device for applying an extraction voltage between the cold field emitter and the extractor device
Implementation Method 4
electron beam optics for directing and focusing the primary electron beam onto the specimen
Implementation Method 5
Upon irradiation of a specimen or sample by a primary charged particle beam, signal charged particles, such as secondary electrons (SE) or backscattered charged particles, are created
Data Source
AI summary
A cold field emitter for emitting an electron beam for an electron beam device is described. The emitter includes an emitter tip having a tip surface; and two or more adjacent facets formed at the tip surface and having facet boundaries, each of the facets forming a recess in the emitter tip, wherein the facets are separated. An intermediate area is provided between and around the two or more adjacent facets and the intermediate area is configured for electron emission. Further, an electron beam device, a method for operating an electron beam device and a method for producing an emitter for an electron beam device is described.