Charged Particle Beam Device Ozone Gas Flow Specimen Charging
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Solution Overview
Problem
Charged particle beam devices face challenges with specimen charging and contamination, particularly in high current density, low voltage electron beam systems, leading to poor imaging quality due to rapid charging and sensitivity of cathodes to gas exposure.
Innovation Solution
Incorporating an ozone unit to direct an ozone gas flow onto the specimen and detector within the charged particle beam device to reduce charging and contamination, using a nozzle system to control the ozone flow and prevent exposure to sensitive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a charged particle beam is directed onto the specimen to achieve high spatial resolution, then imaging quality is improved, but specimen charging and contamination occur leading to degraded performance
Solution Approach 1:
A gas flow (oxygen, nitrogen, or ozone) is introduced as an intermediary between the charged particle beam and the specimen. The gas molecules interact with the beam to generate positive ions that neutralize negative charge on the specimen surface, while also preventing hydrocarbon contamination. This mediator resolves the contradiction by enabling continued beam-specimen interaction for imaging while eliminating the harmful charging and contamination effects.
Solution Approach 2:
The invention changes the chemical and physical parameters of the interaction environment by introducing specific gases (oxygen, nitrogen, or ozone) with controlled flow rates and pressures. These parameter changes modify the interaction products between the charged particle beam and gas molecules, generating beneficial positive ions for charge neutralization while maintaining the beam's imaging capability. The gas pressure and composition are optimized to balance charge neutralization effectiveness with minimal impact on beam performance.
2Reliability
If gas is introduced to neutralize specimen charging, then charging effects are reduced, but detector contamination increases due to carbon layer formation
Solution Approach 1:
The gas flow is directed locally toward the specimen region rather than uniformly across the entire chamber. This localized application ensures that charge neutralization occurs at the specimen surface where it is most needed, while minimizing gas exposure to the detector and other sensitive components. The directional gas flow creates a spatial gradient in gas concentration, with high density near the specimen and lower density toward the detector, thus resolving the contradiction between effective charge neutralization and detector protection.
3Productivity
If high current density is used to improve detection speed, then productivity increases, but charging effects intensify leading to poor imaging quality
Solution Approach 1:
The gas flow is applied continuously during the charged particle beam irradiation process, maintaining a steady supply of gas molecules that continuously generate positive ions to neutralize accumulating negative charge on the specimen. This continuous action ensures that even at high current densities where charge accumulation occurs rapidly, the neutralization process keeps pace, allowing sustained high-speed detection without degradation of imaging quality. The gas flow rate is matched to the beam current to maintain charge neutrality throughout the detection process.
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 ozone gas effectively bleeds off charge from the specimen and removes carbon deposits, improving imaging quality and extending the lifespan of sensitive components by reducing contamination and charging effects.
Implementation Method 1
Due to the interaction with the charged particle beam, the gas molecules are ionized into positive ions and electrons
Implementation Method 2
the positively charged ions are attracted by the specimen where they absorb electrons from the specimen's surface
Implementation Method 3
the charged particle beam splits hydrocarbon molecules that are present in the vacuum and deposits a carbon layer on the sample and the detector
Data Source
AI summary
The invention provides a charged particle beam device for irradiating a specimen, comprising a particle source for providing a beam of charged particles, an optical device for directing the beam of charged particles onto the specimen and an ozone unit for reducing the charging and/or contamination of the specimen. The ozone unit comprises a supply of ozone and a specimen nozzle unit for directing an ozone gas flow to the specimen. Further, the invention provides a charged particle beam device for irradiating a specimen comprising a particle source for providing a beam of charged particles, an optical device for directing the beam of charged particles onto the specimen, a detector and a gas unit for reducing the charging and/or contamination of the detector. The gas unit comprises a supply of gas and a detector nozzle unit for directing a gas flow to the detector. Further, the present invention provides methods for operating charged particle beam devices according to the present invention.