Electron Beam Writer Deflector Layout for Secondary Electron Control
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Solution Overview
Problem
In electron beam writing apparatuses, operating electrostatic lenses in a positive voltage range to guide secondary electrons away from the sample surface leads to contamination on the deflector electrodes, altering the electron beam trajectory and reducing position accuracy due to secondary electron charging.
Innovation Solution
A fixed deflector is introduced downstream of the focus correction lens and positioning deflector, with a constant voltage applied to deflect secondary electrons away from the electron beam trajectory, preventing them from reaching the positioning deflector and maintaining a stable electric field, thus improving beam position accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electrostatic lenses are operated in a positive voltage range to guide secondary electrons upward from the sample surface, then the position accuracy of writing pattern is improved, but secondary electrons pass through the electrostatic lenses and cause contamination on the deflector electrodes, altering the electron beam trajectory and deteriorating beam position accuracy
Solution Approach 1:
A fixed deflector is introduced as an intermediary component between the electrostatic lenses and the positioning deflector. This fixed deflector serves as a mediator that captures and holds secondary electrons through electrostatic attraction, preventing them from reaching the positioning deflector electrodes. The fixed deflector is equipped with a voltage control unit that applies appropriate voltage to create an electrostatic field, attracting secondary electrons onto its surface where they are trapped, thus protecting the positioning deflector from charging effects and maintaining beam position accuracy.
2Manufacturing precision
If a fixed deflector with constant voltage is introduced to deflect secondary electrons away from the electron beam trajectory, then beam position accuracy is improved, but the device complexity increases
Solution Approach 1:
The fixed deflector is designed to perform multiple functions: it serves as both a protective element that prevents secondary electron charging on the positioning deflector, and as an active beam position adjustment component. By integrating these functions into a single component, the need for additional separate protective elements is eliminated, thereby reducing overall device complexity while maintaining improved beam position accuracy.
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 implementation of a fixed deflector with a constant voltage significantly reduces beam position variations and improves accuracy by preventing secondary electron charging on the deflector electrodes, maintaining a stable electric field and minimizing beam trajectory alterations.
Implementation Method 1
a fixed deflector which is disposed downstream of the positioning deflector in a traveling direction of the charged particle beam, and in which an amount of deflection is fixed
Implementation Method 2
the beam of each shot is focused on a sample surface, which is the surface of a substrate, by an object lens, and focus correction (dynamic focusing) is dynamically performed using electrostatic lenses
Data Source
AI summary
In one embodiment, a charged particle beam writing apparatus includes a positioning deflector adjusting an irradiation position of a charged particle beam radiated to a substrate which is a writing target, a fixed deflector which is disposed downstream of the positioning deflector in a traveling direction of the charged particle beam, and in which an amount of deflection is fixed, a focus correction lens performing focus correction on the charged particle beam according to a surface height of the substrate, and an object lens focusing the charged particle beam.