EUV Source-Collector Module Debris Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional laser-produced plasma (LPP) source-collector modules for extreme ultraviolet (EUV) lithography face issues with the vulnerability of multilayer coated collector mirrors due to ion deposition and reduced EUV radiation delivery efficiency, along with significant reflected laser light causing downstream optics and lithography component damage.
Innovation Solution
Incorporating a debris mitigation device to minimize tin vapor deposition on the collector mirror, optimizing the laser target configuration for enhanced EUV production with reduced reflected laser light, and employing a double-sided collection system with a spherical multilayer coated collector to maximize EUV radiation delivery while mitigating infrared radiation interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer coated collector (MCC) is used to reflect 13.5-nm light at normal incidence, then EUV radiation collection efficiency is improved, but the MCC becomes vulnerable to degradation from fast ions and tin vapor deposition, reducing reliability
Solution Approach 1:
A debris mitigation device is introduced as an intermediary component between the LPP source and the GIC mirror. This device intercepts and removes tin vapor and fast ions before they can deposit on the collector mirror surface, thereby protecting the mirror from degradation while maintaining high EUV collection efficiency
Solution Approach 2:
The harmful elements (tin vapor and fast ions) are extracted from the optical path before they can reach and damage the collector mirror. The debris mitigation device selectively removes these harmful components while allowing the desired EUV radiation to pass through and be collected
2Power
If LPP source power is increased to deliver high power EUV radiation to the intermediate focus, then EUV radiation delivery efficiency is improved, but reflected laser infrared radiation increases, causing damage to downstream optics
Solution Approach 1:
The debris mitigation device is designed to selectively interact with different types of radiation based on their properties. It allows the desired EUV radiation to pass through while blocking the harmful infrared radiation, effectively converting the harmful reflected laser light into a blocked component that cannot reach downstream optics
3Reliability
If a grazing-incidence collector (GIC) is used instead of MCC to avoid multilayer coating vulnerability, then reliability is improved, but EUV radiation collection efficiency decreases
Solution Approach 1:
The patent merges the advantages of both GIC and MCC approaches by using a GIC mirror with a debris mitigation device. This combination achieves the reliability of a GIC (no vulnerable multilayer coatings) while improving the EUV collection efficiency through selective debris removal, effectively combining the benefits of both collector types
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 significantly extends the operational lifespan of the collector mirrors, enhances EUV radiation delivery efficiency, and reduces the impact of reflected laser light on downstream components, enabling high-throughput and reliable EUV lithography operations.
Implementation Method 1
at least a first laser operably arranged to generate at least a first light pulse of first infrared (IR) radiation to a location to irradiate the tin droplet target to vaporize and ionize the tin droplet target to form plasma
Implementation Method 2
irradiate the initial plasma to form a final plasma that substantially isotropically emits EUV radiation
Implementation Method 3
a grazing-incidence collector having an optical axis, an input end and an output end... a grazing-incidence collector (GIC) to minimize the deposition of Sn vapor from the LPP onto the surface of the GIC
Implementation Method 4
Incorporating a debris mitigation device to minimize tin vapor deposition on the collector mirror
Implementation Method 5
employing a double-sided collection system with a spherical multilayer coated collector to maximize EUV radiation delivery
Data Source
AI summary
Source-collector modules for use with EUV lithography systems are disclosed, wherein the source-collector modules employ a laser-produced plasma EUV radiation source and a grazing-incidence collector. The EUV radiation source is generated by first forming an under-dense plasma, and then irradiating the under-dense plasma with infrared radiation of sufficient intensity to create a final EUV-emitting plasma. The grazing incidence collector can include a grating configured to prevent infrared radiation from reaching the intermediate focus. Use of debris mitigation devices preserves the longevity of operation of the source-collector modules.