EUV Optical Sensor for Hydrogen Plasma Etching Control
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Solution Overview
Problem
In EUV lithography and mask inspection systems, hydrogen plasma causes etching and contamination of silicon-containing materials, leading to undesired deposition on optical surfaces, which impairs transmission properties, and existing methods struggle to effectively detect and control the composition of the residual gas atmosphere to prevent these issues.
Innovation Solution
A method involving a structural element subjected to chemical etching, with a sensor unit detecting the suppression extent of etching processes using a sensor material that varies under the influence of a suppressing gas component like oxygen or water, allowing for controlled feeding of these gases to reduce etching and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If oxygen is fed into the residual gas atmosphere to reduce etching and dissolution of silicon, then etching suppression is improved, but undesired oxidations increase
Solution Approach 1:
A sensor unit continuously monitors the residual gas atmosphere composition and provides feedback to a control unit, which adjusts the oxygen feed rate in real-time. This closed-loop control ensures etching suppression while preventing excessive oxidation by dynamically balancing oxygen concentration based on actual plasma conditions and gas composition.
Solution Approach 2:
The system dynamically changes the concentration parameter of oxygen in the residual gas atmosphere based on detected plasma conditions and etching rates. By adjusting oxygen partial pressure within optimal ranges, the system achieves effective etching suppression while avoiding harmful oxidations of silicon components.
2Ease of manufacture
If hydrogen plasma is used for cleaning effect, then cleaning performance is improved, but material damage and contamination increase
Solution Approach 1:
The system applies hydrogen plasma cleaning in periodic cycles rather than continuously, alternating between cleaning phases and operation phases. This periodic application provides sufficient cleaning effect while limiting cumulative material damage and contamination buildup on optical surfaces and structural elements.
Solution Approach 2:
The system uses controlled, partial application of hydrogen plasma rather than excessive continuous exposure. By providing just enough plasma exposure to achieve cleaning effects on optical surfaces while avoiding over-exposure that would cause material damage, the system optimizes the balance between cleaning performance and component protection.
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 approach effectively reduces the etching of silicon-containing materials by hydrogen plasma, minimizing contamination on optical surfaces and maintaining optimal transmission properties by precisely metering suppressing gases based on real-time sensor data.
Implementation Method 1
a sensor material section (211) which is composed of a sensor material and which has a sensor section property that can be measured and that can change as a result of a reduction process or an oxidation process
Implementation Method 2
a sensor material section (211) which is composed of a sensor material and which has a sensor section property that can be measured and that can change as a result of a reduction process or an oxidation process
Implementation Method 3
a structural element (201) which is formed at least partly from an element material (203) which is subjected to a chemical etching process, in particular a reduction process as precursor stage to the actual etching process, with a plasma component (PK)
Data Source
AI summary
A method for operating an optical apparatus (100A, 100B, 200), having a structural element (201) which is arranged in a residual gas atmosphere (RGA) of the apparatus and which is formed at least partly from an element material subjected to a chemical reduction process and/or an etching process with a plasma component (PK) present in the residual gas atmosphere includes: feeding (S2) a gas component (GK) that at least partly suppresses the reduction process depending on a detected suppression extent (UM) for a suppression of the etching process and/or reduction process by the suppressing gas component in the residual gas atmosphere; and detecting (S1) the suppression extent with a sensor unit (208) arranged in the residual gas atmosphere. The sensor unit includes a sensor material section (211) composed of a sensor material and exhibiting a sensor section property that is measurable under the influence of the suppressing gas component.