EUV Shroud Cooling for Tin Deposition Control
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Solution Overview
Problem
In EUV light generation systems, tin deposition on reflective surfaces and shroud components occurs due to stannane gas dissociation, leading to reduced reflectance and potential obstruction of optical paths, especially at high temperatures, which complicates microfabrication at 32 nm or less.
Innovation Solution
Incorporating a cooling mechanism within the EUV chamber apparatus, including a shroud with a flow path for a cooling medium that circulates to maintain the temperature of the shroud, EUV light condensing mirror, and heat shield at a stable temperature, preventing tin deposition and maintaining reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shroud and optical components are positioned in the high-temperature region near the plasma generation zone, then they can effectively shield and condense EUV light, but tin deposition occurs on these surfaces due to stannane gas dissociation, reducing reflectance and obstructing optical paths
Solution Approach 1:
The shroud is divided into multiple sections (first shroud, second shroud, third shroud) with different functions and temperature zones. The first shroud is in the high-temperature region for shielding, the second shroud is in the medium-temperature region for transition, and the third shroud is in the low-temperature region for condensing, allowing each segment to operate optimally without tin deposition
Solution Approach 2:
A gas flow (hydrogen or nitrogen) is introduced as an intermediary medium between the plasma generation zone and the shroud components. This gas flow carries dissociated tin atoms away from the shroud and optical components before they can deposit, preventing reflectance degradation and optical path obstruction
2Manufacturing precision
If the shroud is placed close to the target to improve shielding efficiency, then optical path obstruction is reduced, but the shroud temperature increases, accelerating stannane dissociation and tin deposition
Solution Approach 1:
The shroud system is segmented into multiple parts positioned at different distances from the target. The first shroud is positioned close to the target for effective shielding, while subsequent shrouds are positioned progressively farther away, creating a temperature gradient that prevents excessive heating and tin deposition on any single component
Solution Approach 2:
A gas flow is introduced as an intermediary protective medium that flows between the hot target region and the shroud components. This gas flow physically transports tin atoms away from the shroud surfaces, preventing deposition even when shrouds are positioned close to the target for optimal shielding
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 cooling mechanism effectively prevents tin deposition and maintains the reflectance of the EUV light condensing mirror and shroud, reducing the likelihood of optical path obstruction and ensuring consistent performance in microfabrication processes.
Implementation Method 1
a shroud (8a) including a flow path (8b) for a cooling medium and surrounding at least part of the trajectory of the target (27)
Implementation Method 2
a laser apparatus configured to irradiate the target with a pulse laser beam to generate plasma from the target
Implementation Method 3
an EUV light condensing mirror disposed inside the chamber
Data Source
AI summary
An EUV chamber apparatus includes: a chamber; a target generation unit configured to output a target toward a predetermined region inside the chamber; a gas nozzle through which gas is supplied into the chamber; and a shroud including a first flow path through which a first cooling medium circulates and surrounding at least part of the trajectory of the target inside the chamber.