Sample Decontamination via Ozone Oxidation for Ion Beam Imaging
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Solution Overview
Problem
Ion beam imaging is hindered by surface contaminants, particularly hydrocarbons, which reduce image quality and accuracy due to the sensitivity of light ion beams to sample surfaces, leading to decreased contrast and resolution, especially at high magnification.
Innovation Solution
Exposing samples to a reactive gas, such as ozone, which reacts with surface contaminants to form volatile products that are removed, allowing for continuous decontamination during imaging without disrupting the ion beam, and using a gas field ion source to maintain chamber cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reactive gas (ozone) is introduced to react with and remove surface contaminants, then image quality (contrast and resolution) is improved, but the complexity of the imaging system increases due to additional gas delivery and removal infrastructure
Solution Approach 1:
Ozone is introduced into the chamber to react with hydrocarbon contaminants on the sample surface, forming volatile products that are removed by the pumping system. This chemical oxidation process effectively cleans the sample surface during imaging, improving image contrast and resolution without requiring separate cleaning steps.
Solution Approach 2:
The reactive gas is delivered continuously or periodically during the ion beam imaging process, maintaining sample surface cleanliness throughout the imaging session. The pumping system operates continuously to remove volatile reaction products, ensuring the decontamination process does not interrupt the imaging workflow.
2Measurement precision
If the chamber pressure is reduced to maintain ion beam quality, then image accuracy is improved, but contaminants are more likely to deposit on the sample surface
Solution Approach 1:
The chamber is maintained at reduced pressure (vacuum conditions) to protect the ion beam from atmospheric interference, ensuring high image accuracy. Simultaneously, ozone is introduced at controlled low concentrations to provide decontamination without compromising the vacuum quality or ion beam performance.
Solution Approach 2:
Ozone reacts with deposited hydrocarbon contaminants even in the reduced pressure environment, converting them to volatile products that are rapidly pumped away. This prevents contaminant accumulation on the sample surface while maintaining the vacuum conditions necessary for high-quality ion beam 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
This method enhances image contrast and resolution by reducing surface contaminants, enabling high-magnification imaging with improved accuracy and maintaining chamber cleanliness, even during periods without samples, while preventing reactive gas interference with the ion source.
Implementation Method 1
exposing a sample in a chamber to ozone, where the ozone reacts with surface contaminants on the sample to form volatile reaction products
Implementation Method 2
exposing the sample to a charged particle beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles. The charged particle beam includes particles having a molecular weight of 40 atomic mass units or less. The charged particle beam can include noble gas ions (e.g., helium ions)
Implementation Method 3
The method can include producing the charged particle beam in a gas field ion source. The gas field ion source can include a tip configured to produce an electric field that ionizes gas molecules to form the charged particle beam
Data Source
AI summary
Disclosed herein are methods that include: (a) exposing a sample in a chamber to a first gas, where the first gas reacts with surface contaminants on the sample to form a second gas; (b) removing at least a portion of the second gas from the chamber; and (c) exposing the sample to a charged particle beam to cause a plurality of particles to leave the sample and detecting at least some of the plurality of particles. The charged particle beam can include particles having a molecular weight of 40 atomic mass units or less.