Electron Gun Channel Width and Sweep Electrode Design
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Solution Overview
Problem
Current electron gun systems face challenges in maintaining high yield and efficiency due to the interaction between primary and secondary electrons, which degrades resolution and brightness, particularly in semiconductor manufacturing where critical dimensions are shrinking and production time needs to be minimized.
Innovation Solution
The electron gun system incorporates a magnetic field source and a channel with an inner width dimension less than or equal to twice the Larmor radius of secondary electrons, along with a sweep electrode generating an electric field to increase kinetic energy of secondary electrons, thereby reducing their residency time and interaction with the primary beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the channel inner width dimension is reduced to minimize secondary electron interaction, then beam resolution and brightness are improved, but the channel becomes more susceptible to space charge effects from secondary electrons
Solution Approach 1:
A magnetic field is introduced as an intermediary force to manipulate secondary electrons. The magnetic field causes secondary electrons to follow curved trajectories (Larmor orbits) within the channel, confining them away from the primary beam path and reducing space charge effects while maintaining the narrow channel geometry for high resolution.
Solution Approach 2:
The patent changes the magnetic field strength parameter to control the Larmor radius of secondary electrons. By adjusting the magnetic field, the Larmor radius is reduced to be less than or equal to twice the channel inner width dimension, optimizing the balance between confining secondary electrons and maintaining beam quality.
2Illumination intensity
If the Larmor time of secondary electrons is increased to reduce interaction with primary beam, then beam brightness is maintained, but secondary electrons remain in the channel longer potentially increasing space charge accumulation
Solution Approach 1:
The patent creates a dynamic balance where secondary electrons undergo multiple Larmor orbits (increasing Larmor time) but are continuously redirected by the magnetic field. This dynamic confinement allows electrons to remain in the channel longer without accumulating, as their trajectories are controlled to prevent convergence and space charge buildup.
3Reliability
If a magnetic field is applied to control secondary electron trajectories, then space charge effects are reduced, but the system complexity and manufacturing difficulty increase
Solution Approach 1:
The magnetic field system serves multiple functions: it confines secondary electrons to reduce space charge effects, controls their trajectories to maintain brightness, and regulates their residence time in the channel. This multi-functionality justifies the added complexity by achieving multiple performance improvements with a single system component.
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 configuration reduces the negative effects of secondary electrons on the primary beam, improving optical performance by minimizing beam deflection and maintaining brightness and resolution, allowing for faster and more accurate semiconductor fabrication.
Implementation Method 1
The channel has an inner width dimension perpendicular to a direction the primary beam of electrons is projected. The inner width dimension is less than or equal to twice a value of a Larmor radius of secondary electrons in the channel.
Implementation Method 2
The electron gun system further includes a sweep electrode that generates an electric field in a drift region. The electric field increases kinetic energy of secondary electrons in the channel.
Data Source
AI summary
Electron gun systems with a particular inner width dimension, sweep electrodes, or a combination of a particular inner width dimension and sweep electrodes are disclosed. The inner width dimension may be less than twice a value of a Larmor radius of secondary electrons in a channel downstream of a beam limiting aperture, and a Larmor time for the secondary electrons may be greater than 1 ns. The sweep electrode can generates an electric field in a drift region, which can increase kinetic energy of secondary electrons in the channel.