EUV Optical Plate Protection via Rotating Mask
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Solution Overview
Problem
Optical components in EUV sources, such as coupling-in and diagnostics windows, suffer from fouling due to metal vaporization, leading to reduced transparency and frequent maintenance needs, as existing foil traps are inadequate in capturing all metal vapor and protecting these components effectively.
Innovation Solution
An arrangement featuring a movable and rotatable optical plate with an orificed mask that exposes different regions of its surface to the beam path, distributing fouling over a larger area, combined with gas flow and cleaning gases to prevent fouling, and a gas discharge for immediate surface cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a foil trap is used to reduce metal vapor diffusion, then some metal vapor is captured, but it cannot capture all metal vapor and optical components still become fouled
Solution Approach 1:
The optical plate is divided into multiple functional zones: a fouled region that captures metal vapor deposits and a clean region that remains transparent for optical purposes. This segmentation allows the plate to simultaneously handle both the harmful vapor deposition and maintain optical functionality.
Solution Approach 2:
The optical plate is made rotatable, transforming it from a static component to a dynamic one. By rotating the plate, the system can periodically expose a clean surface to the optical path while the opposite side accumulates fouling, thereby extending operational life without compromising optical performance.
2Reliability
If optical components are protected from metal vapor, then transparency is maintained, but the components require complex protection mechanisms
Solution Approach 1:
The system uses the inherent metal vapor flow pattern to automatically direct fouling away from the optical path. The geometry of the process chamber and vapor source creates a natural flow that deposits metal on the optical plate in a predictable pattern, requiring no active control or complex protection mechanisms.
Solution Approach 2:
The optical plate serves dual functions: it acts as both an optical window for laser coupling and diagnostics, and simultaneously as a sacrificial fouling surface. This multi-functionality eliminates the need for separate protection components.
3Illumination intensity
If the optical plate surface is exposed to the beam path, then optical radiation passes through, but fouling reduces transparency over time
Solution Approach 1:
The optical plate is made rotatable, transforming it from a static component to a dynamic one. By rotating the plate, the system can periodically expose a clean surface to the optical path while the opposite side accumulates fouling, thereby extending operational life without compromising optical performance.
Solution Approach 2:
The system employs periodic rotation of the optical plate to alternate between clean and fouled surfaces. This periodic action allows the optical path to consistently receive high-quality transmission while the fouling accumulates on alternative surfaces that are later replaced or cleaned.
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 solution significantly extends the operational life of EUV sources by reducing absorption of laser pulses, allowing lower-energy lasers and minimizing interference with diagnostics, while maintaining stable EUV source operation and reducing maintenance intervals.
Implementation Method 1
different regions of the surface are exposed in succession through the orifice of the orificed mask as a result of continuous or step-by-step movement of the optical plate
Implementation Method 2
combined with gas flow and cleaning gases to prevent fouling
Implementation Method 3
a gas discharge for immediate surface cleaning
Implementation Method 4
an orificed mask that is arranged in front of the optical plate and that has an orifice through which a region of the surface of the optical plate is exposed
Data Source
Figure 1~2
Figure 3
AI summary
An arrangement and a method for protecting an optical component (27) in or on a process chamber, through which component optical radiation passes or by which optical component optical radiation is produced or reflected. The arrangement comprises an optical plate (28) that is arranged in front of the optical component and an orificed mask (29) that is arranged in front of the optical plate and that has an orifice through which a region of the surface of the optical plate is exposed on a preset axis of the beam of optical radiation. Remaining regions of the surface of the optical plate are covered, on the orificed-mask side, by the orificed mask and/or by other screening elements for protecting against fouling. The optical plate is so moved in translation and/or rotation that different regions of the surface are exposed in succession through the orifice of the orificed mask. The present arrangement and the associated method produce a lengthening of the life of the optical component and hence of the interval between two maintenance operations.