EUV Droplet Catcher Gutter for Collector Contamination
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Solution Overview
Problem
Existing EUV lithography systems face contamination issues due to unused target droplets hitting the collector's reflective surface, leading to reduced reflectivity and a shorter usable lifetime, as these droplets accumulate and cause debris on the reflective optics.
Innovation Solution
A droplet catcher with a gutter system on its inner bottom surface is designed to collect and redirect unused target droplets under gravity, preventing them from hitting the collector and promoting recycling, thereby reducing contamination and extending the collector's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional droplet catcher without a gutter system is used, then the structure is simple, but unused target droplets accumulate on the inner surface causing contamination and reducing collector lifespan
Solution Approach 1:
The droplet catcher is segmented into distinct functional zones: an upper collection region and a lower gutter system. The gutter acts as a separate drainage channel that collects and redirects droplets away from the collector, preventing accumulation while maintaining structural integrity. This segmentation allows the droplet catcher to perform multiple functions (collection and redirection) without requiring a completely new design.
Solution Approach 2:
The gutter system serves as an intermediary element between the droplet entry point and the collector. Instead of droplets directly contacting the collector or accumulating on horizontal surfaces, the gutter provides an intermediate pathway that channels droplets to a designated exit or collection point, thereby protecting the collector from contamination.
2Object-affected harmful factors
If droplets are allowed to accumulate on the inner surface of the droplet catcher, then no additional structures are needed, but contamination occurs and reflectivity decreases
Solution Approach 1:
The harmful accumulation of droplets on horizontal surfaces is extracted and redirected into the gutter system. The gutter acts as a dedicated drainage pathway that removes droplets from the problematic accumulation zones and transports them to a safe discharge point, effectively separating the contamination source from the collector surface.
Solution Approach 2:
The solution introduces a vertical dimension to droplet management by incorporating a sloped gutter that directs droplets downward. Instead of allowing droplets to spread horizontally across surfaces where they cause contamination, the gutter utilizes gravity to channel them vertically to a collection point below, changing the dimension of droplet transport.
3Productivity
If the inner bottom surface is made horizontal, then manufacturing is simple, but droplets do not drain effectively and backsplash occurs
Solution Approach 1:
The gutter system introduces asymmetry into the otherwise symmetric cylindrical droplet catcher. By creating a localized depression or channel with a specific slope, the design breaks the symmetry to enable effective drainage. This asymmetric feature is minimal and can be manufactured through standard processes like machining or molding, while dramatically improving droplet redirection and recycling efficiency.
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 gutter system effectively minimizes backsplash and enhances the recycling rate of unused target droplets, reducing contamination on the collector's surface and prolonging its operational life by directing them towards a reservoir for reuse.
Implementation Method 1
the sloped gutter directs the flow of the collected unused target droplets under the influence of gravity
Implementation Method 2
The droplet catcher may further include a heating element thermally coupled to the first pipe wall portion to heat the first pipe wall portion
Implementation Method 3
so that the micro particles or puddles accumulated on its inner surface will be melted to return to the liquid or droplet state
Data Source
AI summary
An extreme ultraviolet radiation source is provided, including a droplet generator and a droplet catcher. The droplet generator is configured to output a plurality of target droplets along a target droplet path that is parallel to a horizontal direction. The droplet catcher includes an open end substantially aligned with the target droplet path, and an enclosed end that is opposite to the open end. The droplet catcher also includes a pipe wall disposed between the open end the enclosed end. The pipe wall includes a first pipe wall portion having an inner top surface parallel to the horizontal direction and an inner bottom surface inclined relative to the inner top surface. In addition, the droplet catcher includes at least one gutter formed on the inner bottom surface and having a long axis extending along the horizontal direction.