Ion Beam Current Segmentation for Sample Protection
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Solution Overview
Problem
Existing charged particle beam systems, such as electron beam systems, require modifications to electron optics when adjusting current, which can lead to sample damage and undesirable effects like electrostatic charging and beam aperture damage, especially when working with insulators or crystalline samples.
Innovation Solution
Employing a method that uses a high ion beam current for tuning and focusing, followed by a low ion beam current for investigation and modification, with the low current beam being applied over a longer period to reduce sample and optics damage, while maintaining the same particle dose, and utilizing a gas field ion source to generate beams with adjustable pressures and optics settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high charged particle beam current is used to investigate and modify a sample, then the investigation and modification process can be completed faster, but sample damage increases and electrostatic charging problems occur
Solution Approach 1:
The patent divides the charged particle beam operation into two distinct stages: a first stage using high current for rapid investigation and modification, and a second stage using low current to complete the process. This segmentation allows the system to benefit from both high productivity during the main processing phase and reduced sample damage during the final phase, resolving the contradiction between speed and sample integrity
Solution Approach 2:
The patent implements periodic alternation between high current and low current beam modes. The system operates in cycles, switching from high current (for productivity) to low current (for sample protection) at predetermined intervals or based on process conditions. This periodic action allows the system to achieve both fast processing and reduced cumulative sample damage
2Loss of time
If a high charged particle beam current is used, then the charged particle beam can be applied over a shorter period, but electrostatic charging and arcing problems increase
Solution Approach 1:
The patent segments the beam application process into two temporal phases: an initial phase using high current to minimize total process time, and a subsequent phase using low current to reduce electrostatic charging. This time-based segmentation allows the system to optimize for both speed and electrical stability by matching current level to process stage
Solution Approach 2:
The patent applies high current beam in the preliminary stage of the process when the sample has not yet accumulated significant charge, thereby minimizing total processing time. By performing the time-critical operations first while the sample is still electrically stable, the system achieves fast processing without triggering arcing problems that would occur if high current were applied after charging had already occurred
3Productivity
If a high charged particle beam current is used for tuning and focusing, then the beam can be tuned quickly, but the region of interest on the sample is exposed to high current
Solution Approach 1:
The patent separates the beam tuning operation from the sample investigation region by using a spatial segmentation approach. The high current beam is directed to a tuning region on the sample that is distinct from and separate from the region of interest. This allows rapid beam tuning using high current without exposing the sensitive region of interest to damaging high current exposure
Solution Approach 2:
The patent introduces an intermediary tuning region on the sample that serves as a buffer zone. This intermediate region absorbs the high current exposure during tuning and focusing operations, protecting the region of interest from direct high current damage. The tuning region acts as a mediator that enables fast beam setup while isolating the critical sample area from harmful effects
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 approach minimizes sample and optics damage, reduces electrostatic charging, and prevents undesirable species buildup, allowing for precise investigation and modification with reduced risk of arcing and beam aperture damage.
Implementation Method 1
A gas field ion source can be used to generate an ion beam
Data Source
AI summary
Charged particle beams with different charged particle currents are disclosed. In some embodiments, a method includes exposing a sample to a first ion beam having a first ion current at the sample, and exposing the sample to a second ion beam having a second ion current at the sample, where the first ion current is at least two times greater than the second ion current. In certain embodiments, a method includes creating a first ion beam at a first pressure, exposing a sample to the first ion beam, creating a second ion beam at a second pressure, and exposing the sample to the second ion beam, where the first pressure is at least two times greater than the second pressure.