EUV Collector Mirror Gas Ejection Timing for Debris Control
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Solution Overview
Problem
Current extreme ultraviolet (EUV) light generation systems for semiconductor microfabrication face challenges in maintaining the reflectivity of EUV light collector mirrors due to debris deposition, which affects the intensity distribution of outputted EUV light, particularly at feature sizes below 32 nm.
Innovation Solution
An EUV light generation apparatus with a gas ejection device positioned to ensure etching gas reaches the reflective surface after the EUV light emission cycle, maintaining a cleaning unnecessary distance from the gas ejection opening to the effective reflective area, and determining the gas ejection opening position based on the time required for the etching gas to travel this distance, ensuring continuous and effective etching of debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas ejection device is positioned close to the reflective surface, then the etching gas can quickly reach the surface for effective debris removal, but the gas may interfere with the EUV light emission process and reach the reflective surface during the emission cycle causing contamination
Solution Approach 1:
The gas ejection device is positioned at a calculated distance from the reflective surface so that the etching gas reaches the surface only after the EUV light emission cycle is complete. This timing ensures that gas ejection does not interfere with light generation while still providing timely debris removal in the subsequent cycle.
Solution Approach 2:
The system dynamically coordinates the gas ejection timing with the pulsed laser emission cycle. By controlling when gas is ejected relative to when laser pulses occur, the system adapts the cleaning process to avoid interfering with light generation while maintaining effective debris removal.
2Reliability
If the gas ejection opening is positioned far from the reflective surface, then the EUV light emission is not interfered with, but the etching gas takes longer to reach the surface reducing cleaning effectiveness
Solution Approach 1:
The system optimizes the gas ejection opening position by calculating the precise distance that allows gas to reach the reflective surface in a time longer than the emission cycle. This parameter optimization balances non-interference with light emission while maintaining effective cleaning speed.
3Productivity
If continuous gas ejection is used to maintain constant cleaning, then debris removal is effective, but the gas flow may accumulate and interfere with subsequent EUV light emission cycles
Solution Approach 1:
The gas ejection device operates in periodic cycles synchronized with the laser emission cycles. Gas is ejected during intervals between laser pulses rather than continuously, ensuring debris removal effectiveness while preventing gas accumulation that would interfere with light emission.
Solution Approach 2:
The system maintains continuous debris removal effectiveness through coordinated periodic gas ejection cycles, while ensuring that gas flow does not accumulate to harmful levels by timing ejection to complete before the next emission cycle begins.
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 configuration maintains the reflectivity of the EUV light collector mirror by ensuring continuous etching of debris, preventing debris adhesion and maintaining suitable intensity distribution for exposure applications, even at smaller feature sizes.
Implementation Method 1
a reflective surface configured to reflect and collect extreme ultraviolet light generated at a predetermined emission cycle because of irradiation of the successively supplied targets with a laser beam
Implementation Method 2
a gas ejection device disposed in the through-hole to jut out from the reflective surface and have a gas ejection opening to eject etching gas for debris onto the reflective surface
Data Source
AI summary
An extreme ultraviolet light generation apparatus may include a chamber, a target supply device configured to successively supply targets into the chamber, and an extreme ultraviolet light collector mirror including a reflective surface having a through-hole at the center thereof. The reflective surface may reflect and collect extreme ultraviolet light generated at a predetermined emission cycle because of irradiation of the successively supplied targets with a laser beam. A gas ejection device may be disposed in the through-hole to jut out from the reflective surface and have a gas ejection opening to eject etching gas for debris onto the reflective surface. The gas ejection device may be configured so that the etching gas takes a longer time than the predetermined emission cycle to reach the through-hole-side end of effective reflective area of the reflective surface after being ejected from the gas ejection opening.