EUV Collector Protection Vanes Deflect Source Material
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Solution Overview
Problem
Optical elements in EUV light generation systems face contamination and physical damage from source materials, leading to reduced reflectivity and lifetime, despite existing protective measures, as source material accumulates and detaches from interior surfaces within the vacuum chamber.
Innovation Solution
The use of vane structures made from corrosion-resistant materials like molybdenum or stainless steel, coated with inert materials like gold, positioned on the interior walls of the vacuum chamber to deflect and collect contaminating source material, with heating elements and mesh surfaces to prevent accumulation and direct material to a collection vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanes are used to protect the collector from micro-droplets of source material, then the collector is protected from contamination, but source material accumulates on the vanes which may detach and impinge on the collector surface
Solution Approach 1:
The protective function is divided between multiple components: vanes for primary protection and a mesh screen for secondary protection. The mesh screen is positioned downstream of the vanes to catch any source material that passes through or detaches from the vanes, creating a segmented defense system that addresses the accumulation problem
Solution Approach 2:
The mesh screen acts as an intermediary protective layer between the source material and the collector. It is positioned in the path of source material flow to intercept and retain material before it can reach the collector, preventing both direct contamination and detachment issues
2Reliability
If the collector is heated to elevated temperature to evaporate debris, then surface contamination is reduced, but energy consumption increases and thermal stability becomes challenging
Solution Approach 1:
The mesh screen performs preliminary protection by intercepting source material before it reaches the collector surface. This preventive action reduces the amount of contamination that would otherwise require thermal evaporation, thereby reducing the energy needed for cleaning
Solution Approach 2:
The system converts the harmful source material into a manageable form by having it accumulate on the mesh screen instead of the collector. The mesh screen captures and concentrates the contaminant in a controlled location where it can be managed without requiring high-energy evaporation processes
3Duration of action of stationary object
If protective layers are used to isolate the MLM layers from the environment, then optical element lifetime is extended, but device complexity increases
Solution Approach 1:
The mesh screen serves as a disposable or easily replaceable protective component that absorbs the brunt of source material exposure. Instead of complex multi-layer protective coatings on the expensive collector, a simpler, less expensive mesh screen is used as a sacrificial protective element
Solution Approach 2:
The mesh screen functions as a thin film structure that provides effective protection without adding significant complexity. It is a simple geometric structure that can be easily installed and maintained, contrasting with complex multi-layer protective coatings
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
Extends the lifetime of optical elements by effectively preventing source material from reaching and accumulating on the collector surfaces, reducing contamination and physical damage, and maintaining reflectivity through targeted heating and mesh-directed collection.
Implementation Method 1
a vane having a first surface which is oriented along a direction between the vane and the region and a second surface adjacent the first surface which is oriented to deflect the contaminating material striking the second surface away from the region
Implementation Method 2
The vane may be heated, and may be heated at least to a melting point of the contaminating material
Implementation Method 3
The collector may be heated to an elevated temperature of, e.g., up to 500° C., to evaporate debris from its surface
Implementation Method 4
At least part of each of the vanes may be covered with a mesh... The mesh may be arranged to direct liquid contaminating material to the vessel
Data Source
AI summary
Apparatus having a chamber with an interior wall and a region within the chamber from which a contaminating material emanates when the apparatus is in operation. A plurality of vanes is positioned on a portion of the interior wall, each of the vanes having a first surface which is oriented along a direction between the vane and the region and a second surface adjacent the first surface which is oriented to deflect the contaminating material striking the second surface away from the region, the second surfaces being dimensioned and juxtaposed with respect to one another such that the second surfaces substantially prevent the contaminating material from striking the portion of the interior wall. At least part of each of the vanes may be covered with a mesh. The vanes may be heated, and may be heated at least to a melting point of the contaminating material. The apparatus is especially applicable to protecting multilayer mirrors serving as collectors in systems for generating EUV light for use in semiconductor photolithography.