Dual-Beam Ion Beam Impurity Identification
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Solution Overview
Problem
Dual-beam systems face challenges in detecting and purging impurities from ion beams, which can damage substrates during manufacturing and inspection processes, as the magnetic field from the SEM interferes with ion beam trajectories and makes it difficult to collect secondary particles effectively.
Innovation Solution
A charged particle beam magnetic lens system that operates in both analysis and imaging modes, allowing for the deflection and identification of ion beam components, enabling the determination of impurity presence and composition by applying specific excitations and using an ion beam collector to measure beam currents and charge-to-mass ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the SEM magnetic field is used for imaging, then imaging quality is improved, but ion beam trajectory control deteriorates
Solution Approach 1:
The patent applies dynamics by making the magnetic lens excitations adjustable and time-varying. The system transitions between imaging mode (with imaging excitations) and analysis mode (with analysis excitations) based on operational requirements. This dynamic switching allows the same magnetic lens to serve dual purposes: providing stable imaging fields when needed and creating variable fields for ion beam separation and analysis when required.
Solution Approach 2:
The patent implements universality by designing the magnetic lens system to perform multiple functions. The charged particle beam magnetic lens is configured to operate in both imaging mode and analysis mode, eliminating the need for separate dedicated imaging and analysis magnetic lenses. This multi-functional approach resolves the contradiction by allowing the system to adapt its function based on operational mode.
2Measurement precision
If the SEM magnetic field is activated for imaging, then substrate imaging is improved, but secondary particle collection deteriorates
Solution Approach 1:
The system uses dynamic switching of magnetic lens excitations to resolve this contradiction. During imaging operations, the magnetic lens is configured with imaging excitations to provide stable magnetic fields for electron optics. When secondary particle collection is needed, the system switches to analysis mode with different excitations that create magnetic fields conducive to particle separation and detection, rather than stable imaging.
Solution Approach 2:
The patent employs periodic action through the alternating between imaging mode and analysis mode operations. The magnetic lens excitations are periodically switched based on the operational requirements - imaging excitations when substrate imaging is needed, and analysis excitations when secondary particle collection and ion beam analysis are required. This periodic switching allows both functions to be optimized at different times.
3Measurement precision
If ion beam analysis mode is used with low excitation, then impurity detection sensitivity is improved, but beam deflection capability deteriorates
Solution Approach 1:
The patent applies local quality by creating different magnetic field conditions in different spatial and operational contexts. In analysis mode, the magnetic lens is configured with specific excitations that create localized magnetic field gradients optimized for separating ion beam components based on their mass-to-charge ratios. This allows sensitive detection of impurities through selective deflection patterns while maintaining adequate overall beam control.
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 allows for the precise identification and removal of impurities from the ion beam, ensuring the purity of the beam and minimizing substrate damage, by deflecting and measuring ion beam components based on their charge-to-mass ratios, thereby enhancing the reliability of dual-beam systems in applications like FIB milling.
Implementation Method 1
the CPB magnetic lens is energized to deflect the ion beam into one or more component beams
Implementation Method 2
the CPB magnetic lens is energized to deflect the ion beam into one or more component beams
Implementation Method 3
an ion beam collector is situated to selectively receive individual component beams of the ion beam and an actuator coupled to the ion beam collector and configured to move the ion beam collector to receive individual component beams of the ion beam
Implementation Method 4
Focused ion beams (FIBs) mill by sputtering, that is, physically removing atoms and molecules from the substrate surface
Data Source
AI summary
A dual beam system having a charged particle beam (CPB) lens and an ion beam column can operate in an analysis mode. In the analysis mode, an ion beam from the ion beam column can be deflected by the CPB into one or more component beams including a primary ion beam and one or more non-primary ion beams. The dual-beam system can identify the ion species of the non-primary ion beams.