Permeable Oxygen Dispensing for Low-Pressure EUV Lithography
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Solution Overview
Problem
Existing fluid dispensing systems in lithographic apparatuses, particularly those using EUV radiation, face challenges in providing small amounts of fluids like oxygen without diluting with a carrier gas, which is undesirable in low-pressure environments, leading to contamination issues such as silane formation and oxidation of optical elements.
Innovation Solution
A fluid dispensing system with a permeable surface and a controller to regulate fluid permeation by controlling pressure and exposed surface area, allowing precise delivery of fluids like oxygen directly into the apparatus without the need for carrier gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If mass flow controller is used to provide oxygen, then fluid delivery is controlled, but the amount required is below operating parameters
Solution Approach 1:
The patent introduces an intermediary approach by using a carrier gas (typically hydrogen or a mixture) through which trace amounts of oxygen are delivered. This allows the use of standard mass flow controllers designed for larger flow rates, while the actual oxygen concentration is controlled at very low levels (parts per million range). The carrier gas acts as a medium to transport the small required amounts of oxygen effectively.
Solution Approach 2:
The system changes the parameter of oxygen delivery from direct high-precision control of absolute flow rates to control of oxygen concentration or partial pressure within the carrier gas. This parameter transformation allows standard mass flow controllers to operate within their optimal ranges while achieving the required trace oxygen delivery.
2Quantity of substance
If oxygen is diluted with carrier gas, then small amounts of oxygen can be provided, but additional gas provision is undesirable in low pressure systems
Solution Approach 1:
The patent applies partial action by providing oxygen at concentrations just sufficient to achieve the desired effect of suppressing silane formation. Rather than maintaining high oxygen levels, the system uses minimal oxygen concentrations (at the threshold of effectiveness), thereby minimizing the total gas load in the low-pressure environment while still achieving the protective effect.
3Reliability
If hydrogen plasma is present, then cooling and cleaning functions are provided, but contamination of optical elements occurs
Solution Approach 1:
The patent converts the harmful interaction between hydrogen plasma and silicon into a beneficial process by carefully controlling oxygen levels. The presence of controlled oxygen suppresses silane formation from hydrogen-silicon reactions, while the hydrogen plasma continues to provide cooling and cleaning functions. The system transforms the potential contamination pathway into a controlled chemical environment where oxygen acts as a protective agent.
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
Enables controlled delivery of small amounts of fluids to mitigate contamination, reducing the need for carrier gases and minimizing damage to optical elements, thus enhancing apparatus throughput and efficiency.
Implementation Method 1
a fluid-permeable surface having a pre-defined permeability to allow permeation of a fluid
Data Source
AI summary
A fluid dispensing system including a fluid-permeable surface having a pre-defined permeability to allow permeation of a fluid, and a controller configured to control the rate of permeation of the fluid into a volume by controlling one or both of a pressure of the fluid and an exposed surface area of the fluid-permeable surface. Also provided is a method of controlling the dispensing of a fluid, a plasma-generating apparatus including such a fluid dispensing system as well as the use of such a system, method, or apparatus in a lithographic apparatus or process.