EUV Light Source Buffer Gas Flow for Target Material Attenuation
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Solution Overview
Problem
EUV light sources face significant attenuation due to target materials like xenon and tin in the light path, leading to increased power generation and operational costs, as well as challenges in removing these materials from the vacuum chamber.
Innovation Solution
A system and method utilizing an exclusionary buffer gas flow, injected through strategically placed injectors within the vacuum chamber, to prevent target material from entering the EUV light path and a vacuum pump to remove both the buffer gas and target material, effectively managing 'stagnation zones' and reducing attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If target material is injected into the vacuum chamber for plasma generation, then EUV light can be produced, but target material accumulates in the chamber including in the EUV light path causing strong attenuation
Solution Approach 1:
A buffer gas (such as helium or argon) is introduced as an intermediary substance that flows through the vacuum chamber and physically separates the target material from the EUV light path. The buffer gas creates a flow field that prevents target material atoms from entering the light path while still allowing plasma generation to occur, thereby reducing attenuation without sacrificing EUV production
Solution Approach 2:
The harmful target material is extracted from the EUV light path by using buffer gas flow to directed transport it toward the exhaust port. The buffer gas creates a flow field that carries target material away from the light path and into the exhaust region where it is removed by the vacuum pump, effectively separating the useful EUV generation function from the harmful material accumulation
2Object-affected harmful factors
If buffer gas is injected to prevent target material from entering the light path, then attenuation is reduced, but additional gas must be removed by the vacuum pump increasing system complexity
Solution Approach 1:
The buffer gas serves multiple functions simultaneously: it acts as a flow medium to prevent target material from entering the light path, it creates a transport field to carry target material to the exhaust port, and it helps maintain vacuum chamber pressure. The vacuum pump removes both the buffer gas and target material together, so the additional complexity of adding buffer gas is offset by the multi-functionality it provides
3Object-affected harmful factors
If vacuum pump removes target material, then attenuation is reduced, but target material accumulates in stagnation zones due to limited interaction with buffer gas flow
Solution Approach 1:
The buffer gas flow is made dynamic and adjustable, with flow rate and direction controlled to adapt to different operating conditions. The flow field is designed to be vigorous enough to prevent stagnation zones but controlled to maintain efficient target material transport to the exhaust port, allowing the system to operate effectively across varying plasma generation rates
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 effectively prevents target material from entering the EUV light path, reducing attenuation and maintaining the integrity of the EUV light source, thereby optimizing power usage and system efficiency while ensuring effective removal of target material from the chamber.
Implementation Method 1
advecting a target material away from a light path using a flow of the buffer gas
Implementation Method 2
a vacuum pump arranged to remove the buffer gas and the target material from the vacuum chamber
Implementation Method 3
using a laser to transform a target material, such as xenon or tin, into plasma
Implementation Method 4
which plasma then emits radiation in the EUV portion of electromagnetic spectrum
Implementation Method 5
EUV light is strongly absorbed by many substances, including xenon and tin
Data Source
AI summary
A system for producing an exclusionary buffer gas flow in an EUV light source, comprising a vacuum chamber, a light path, a plasma generation region, at least one shield, at least one through-bore arranged in the at least one shield, at least one buffer gas injector arranged within the at least one through-bore to inject a buffer gas into the light path substantially towards the plasma generation region to prevent a flow of a target material into the light path, and a vacuum pump arranged to remove the buffer gas and the target material from the vacuum chamber.