Charged Particle Optical Element Vent Holes for Aperture Cleaning
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Solution Overview
Problem
Charged particle beam systems, such as lithography and electron microscopes, face contamination issues due to the accumulation of deposits on optical components, which affects beam accuracy and reliability, particularly in areas with high hydrocarbon partial pressures and beam current densities, limiting the efficiency of existing cleaning methods.
Innovation Solution
Incorporating vent holes with larger cross sections than the charged particle transmitting apertures in the optical elements, along with a cleaning agent source to facilitate the removal of contaminants, reduces pressure and prevents contamination growth, while allowing for efficient cleaning during system operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used in charged particle beam systems, then some contamination removal is achieved, but the cleaning efficiency is limited and contamination accumulates on optical components
Solution Approach 1:
The patent introduces a cleaning gas flow through conduits before the charged particle beam reaches the optical components, performing preliminary cleaning action to prevent contamination accumulation. The cleaning gas is delivered through a network of conduits positioned to reach critical optical elements, creating a protective atmosphere that prevents contaminant deposition before it can occur.
Solution Approach 2:
The patent uses cleaning gas (such as oxygen or plasma) as an intermediary substance between the charged particle beam and the optical components. This intermediary cleaning gas reacts with or removes contaminants on the optical surfaces, protecting the beam path without interfering with the charged particle beam operation. The gas acts as a mediator that maintains optical component cleanliness while allowing continuous beam operation.
2Object-affected harmful factors
If the vacuum chamber maintains high vacuum to prevent contamination, then contaminant accumulation is reduced, but cleaning of existing deposits becomes difficult
Solution Approach 1:
The system performs preliminary cleaning by introducing reactive cleaning gases (such as oxygen plasma or chemical vapor) that react with and remove accumulated hydrocarbon deposits on optical components. This preliminary chemical cleaning action occurs in-situ within the vacuum chamber, converting difficult-to-remove carbon-based contaminants into volatile compounds that can be pumped away, thereby maintaining optical surface quality without requiring chamber breakage for cleaning.
Solution Approach 2:
The patent employs strong oxidizing agents such as oxygen plasma or ozone to accelerate the removal of organic contaminant deposits. The oxidizing environment converts non-volatile hydrocarbon deposits into volatile oxidation products (CO, CO2, H2O) that can be efficiently removed by the vacuum pumping system, thereby enabling effective cleaning of optical components while maintaining high vacuum conditions.
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 solution effectively reduces contamination on charged particle optical elements, maintaining beam properties and stability by continuously removing contaminants at a rate higher than their accumulation, preventing the formation of contamination layers and ensuring consistent system performance.
Implementation Method 1
vent hole for providing a flow path between a first side and a second side of the charged particle optical element... reduces pressure and prevents contamination growth
Implementation Method 2
source for providing a cleaning agent... facilitates the removal of contaminants
Data Source
AI summary
A charged particle beam system is disclosed, comprising:a charged particle beam generator for generating a beam of charged particles;a charged particle optical column arranged in a vacuum chamber, wherein the charged particle optical column is arranged for projecting the beam of charged particles onto a target, and wherein the charged particle optical column comprises a charged particle optical element for influencing the beam of charged particles;a source for providing a cleaning agent;a conduit connected to the source and arranged for introducing the cleaning agent towards the charged particle optical element;wherein the charged particle optical element comprises:a charged particle transmitting aperture for transmitting and/or influencing the beam of charged particles, andat least one vent hole for providing a flow path between a first side and a second side of the charged particle optical element,wherein the vent hole has a cross section which is larger than a cross section of the charged particle transmitting aperture.Further, a method for preventing or removing contamination in the charged particle transmitting apertures is disclosed, comprising the step of introducing the cleaning agent while the beam generator is active.