Wien Filter Velocity Deflection for Beam Purity
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Solution Overview
Problem
Particle-beam apparatuses face issues with beam impurities causing image defects due to mass and energy deviations, leading to increased complexity, aberration, and damage to optics components, particularly with conventional Wien filters that incur high Coulomb interaction and mechanical complexity.
Innovation Solution
A velocity-dependent deflector system using a dipole electrical or magnetic field is introduced to deflect particles based on their velocity, allowing for the selection of nominal species and removal of impurities at a delimiting means, reducing optical column length and complexity, and enhancing the lifetime of beam-absorbing elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional Wien filter is used to remove beam impurities, then image quality is improved, but the optical column length and device complexity increase
Solution Approach 1:
The patent extracts the beam impurity removal function from the conventional Wien filter configuration and relocates it to a dedicated filter unit positioned after the projection system. This separation allows the main optical column to remain compact while the filter unit handles impurity removal independently, resolving the contradiction between image quality improvement and optical column length reduction.
Solution Approach 2:
The patent moves the beam filtering operation from the spatial dimension (within the optical column) to the temporal dimension (after beam formation, before target irradiation). By positioning the filter unit downstream, the system achieves impurity removal without extending the critical optical path length, effectively using time sequencing to resolve the spatial constraint.
2Manufacturing precision
If a Wien filter is used to filter beam impurities, then image defects are reduced, but mechanical and electrical complexity increase
Solution Approach 1:
The patent segments the beam processing system into distinct functional modules: the main projection system for beam formation and a separate filter unit for impurity removal. This modular segmentation allows each component to be optimized independently, reducing the mechanical and electrical complexity within the main optical column while maintaining effective beam filtering through the dedicated downstream unit.
3Manufacturing precision
If beam limiting apertures are used in a Wien filter to absorb deflected particles, then impurity removal is achieved, but the apertures suffer from high current density damage
Solution Approach 1:
The patent introduces an intermediary beam filtering mechanism in the downstream filter unit that distributes the beam current more evenly across the filtering structure. This intermediary approach prevents the concentration of high current density at specific aperture points, thereby extending the operational lifetime of the beam-absorbing elements while maintaining effective impurity removal.
Solution Approach 2:
The patent employs a disposable or easily replaceable filter element in the downstream unit that is specifically designed to absorb beam impurities. This element can be periodically replaced without affecting the main optical system, effectively managing the trade-off between beam purity achievement and component lifetime by separating the consumable filtering function from the permanent optical infrastructure.
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 solution significantly reduces the length and complexity of the optical column, minimizes disturbances from external fields, and extends the drift length of deflected particles, enabling operation at higher beam energies with reduced Coulomb interaction and increased throughput, while maintaining image quality and extending the life of absorbing elements.
Implementation Method 1
a velocity-dependent deflector means adapted to form a deflecting field comprising a dipole electrical field transversal to the optical path and/or a dipole magnetic field transversal to the optical path, the deflecting field being adapted to act upon the particles, causing a deviation of the path of particles
Data Source
AI summary
In a particle-beam apparatus for irradiating a target, a pattern defined in a pattern definer is projected onto the target through a projection system by a beam of energetic electrically charged particles of, largely, a species of a nominal mass having a nominal kinetic energy. To generate the beam, a particle source, a velocity-dependent deflector and an illumination optics system are provided. The velocity-dependent deflector includes a transversal dipole electrical field and/or a transversal dipole magnetic field, which act upon the particles so as to causing a deviation of the path of the particles with regard to the paths of the nominal species which is dependent on the velocity of the particles. A delimiter is provided as a component of the pattern definer or, preferably, the projection system, serving to remove particles whose paths are deviating from the nominal path.