Gas Field Ion Column Energy Width Reduction
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Solution Overview
Problem
The energy width of ion beams emitted from gas field ion sources is deteriorated by superimposed tip protrusions and ionization/scattering mechanisms, leading to a reduction in resolution due to increased energy spread, which is not effectively addressed by existing technologies.
Innovation Solution
A method and apparatus that generate a primary ion beam using a gas field ion source and incorporate an energy filter, specifically a retarding lens, to reduce the energy width of the ion beam by high-pass energy filtering, thereby maintaining the beam's resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If superimposed tip protrusions are used in gas field ion source, then beam intensity is improved, but energy width increases leading to reduced resolution
Solution Approach 1:
The patent extracts and removes ions with energies below a certain threshold using an energy filter (retarding lens), separating the desired high-energy ions from the lower-energy ions that contribute to energy width broadening. This allows maintaining beam intensity while reducing energy spread.
Solution Approach 2:
The patent changes the energy parameter of the ion beam by applying a retarding voltage to filter out low-energy ions. By adjusting the filter voltage, the energy distribution of the transmitted beam is modified to achieve narrower energy width while preserving sufficient beam intensity for practical use.
2Measurement precision
If monochromators are used to reduce energy spread, then energy width is reduced improving resolution, but beam intensity is considerably reduced and device complexity increases
Solution Approach 1:
The patent replaces expensive, complex monochromators with a simpler energy filter (retarding lens) that achieves energy width reduction through a straightforward voltage-based filtering mechanism, significantly reducing device complexity and cost.
Solution Approach 2:
The patent substitutes complex mechanical monochromator systems with an electrostatic energy filter using retarding lenses and voltage controls, replacing mechanical energy selection with electrical field-based energy filtering.
3Measurement precision
If monochromators are used to reduce energy spread, then energy width is reduced improving resolution, but beam intensity is considerably reduced
Solution Approach 1:
The patent applies partial filtering by setting the retarding voltage to remove only the low-energy tail of the energy distribution, rather than filtering all ions. This partial action maintains sufficient beam intensity while achieving the necessary energy width reduction for high-resolution imaging.
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 energy width of the ion beam is reduced from 2-4 eV to 0.2-0.7 eV, enhancing the resolution and maintaining beam intensity, allowing for improved performance in inspection and lithography applications.
Implementation Method 1
a gas field ion source for providing a primary ion beam
Implementation Method 2
an energy filter adapted for reducing the energy width of the primary ion beam
Data Source
AI summary
An ion beam apparatus and a method for providing an energy-filtered primary ion beam are described. Therein, a primary ion beam having an asymmetric first energy distribution is generated by means of an ion source. The primary ion beam is energy filtered using, for example, a retarding lens.