Vacuum Actuator Containment for EUV Particle Mitigation
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Solution Overview
Problem
Current particle control methods in EUV reticle inspection tools are inadequate for eliminating particles down to 10 nm in diameter, especially since cleaning is not allowed after inspection, and existing solutions cause vibrations detrimental to precision optics.
Innovation Solution
A system with a sealed actuator compartment and a filter assembly comprising multiple particle filters and a purifier medium, positioned between the actuator compartment and the vacuum chamber, effectively captures particles and VOCs, preventing them from reaching the optical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particle control methods are used in EUV reticle inspection tools, then particle removal capability is improved, but cleaning after inspection is not allowed and existing methods cannot eliminate particles down to 10 nm in diameter
Solution Approach 1:
The vacuum chamber is divided into two separate chambers: a first vacuum chamber housing the actuator and a second vacuum chamber housing the optical components. This segmentation isolates the particle-generating actuator from the particle-sensitive optics, allowing particle control without compromising the ability to eliminate small particles down to 10 nm in the optical path.
Solution Approach 2:
A vacuum barrier (bellows) is introduced as an intermediary element between the actuator chamber and the optical chamber. This bellows provides a sealed connection that maintains vacuum isolation while allowing mechanical actuation to pass through, effectively mediating between the particle-generating actuator and the particle-free optical environment.
2Reliability
If vacuum pumping is used to control particles, then particle reduction is improved, but vibrations are generated that are detrimental to precision aligned optics
Solution Approach 1:
The vacuum system is segmented into two independently pumped chambers. The first vacuum chamber containing the actuator is pumped separately from the second vacuum chamber containing the optics. This allows the pump serving the actuator chamber to operate without transmitting vibrations to the precision optics in the isolated optical chamber.
Solution Approach 2:
The vacuum barrier (bellows) acts as a vibration-isolating intermediary between the two vacuum chambers. While maintaining vacuum continuity, the bellows structure prevents vibration transmission from the actuator chamber pump to the sensitive optical components.
3Measurement precision
If actuators are used to move optics in vacuum, then alignment precision is improved, but particles and VOCs are generated that contaminate optical surfaces
Solution Approach 1:
The system is segmented into an actuator chamber and an optical chamber, with the actuator and its particle-generating components confined to the first vacuum chamber. The optical components reside in the second vacuum chamber, isolated from actuator-generated contaminants. This allows precise actuation to occur without contaminating the optical surfaces.
Solution Approach 2:
The vacuum barrier serves as a protective intermediary that blocks particles and VOCs generated by the actuator from reaching the optical components. It maintains the vacuum environment needed for precise actuation while preventing contaminant migration to the optical chamber.
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 system achieves more than 90% capture efficiency for particles 3 nm or larger, reducing contamination and minimizing vibrations, thereby enhancing the precision and reliability of EUV semiconductor inspection tools.
Implementation Method 1
The bellows provides a seal between the base and the optic mount
Implementation Method 2
Gas evacuated from the actuator compartment passes through a filter assembly between the actuator compartment and the vacuum chamber
Implementation Method 3
The filter assembly includes a first particle filter, a second particle filter, and a purifier medium disposed between the first particle filter and the second particle filter
Data Source
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AI summary
An actuator for an optic mount in a vacuum environment includes a bellows around an actuator compartment. The bellows provides a seal around the actuator. A filter assembly is positioned between the actuator compartment and an interior of a vacuum chamber. The filter assembly includes a first particle filter, a second particle filter, and a purifier medium between the first particle filter and the second particle filter. Vacuum conditions in the actuator compartment can be achieved with a pump for the vacuum chamber, but particles and contaminants from the actuator or actuator compartment are captured by the filter assembly.