Fluoride Optical Coating Deposition With Penning Plasma Compaction
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Solution Overview
Problem
Optical elements, particularly in the DUV/VUV wavelength range, face degradation due to fluorine depletion and high-energy particle interactions, leading to optical losses and reduced radiation stability, with existing sealing methods being complex and costly, and current compacting techniques often resulting in elevated optical losses.
Innovation Solution
A method involving a gas mixture with a noble gas and a second gas of lower ionization energy, utilizing Penning ionization to increase active energy per molecule without raising ion energy, allowing for high-degree compaction of coating materials with reduced risk of damage from high-energy ions, and using a plasma source with independently adjustable ion energy and current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma ion-assisted deposition is used to compact coating layers, then the packing density of the coating material increases, but optical losses increase due to color center formation from plasma interaction
Solution Approach 1:
The patent changes the energy parameters of the plasma by using a gas mixture where the second gas has lower ionization energy than the first gas. This allows the plasma to provide sufficient ionization for compaction while reducing the formation of color centers that cause optical losses, thereby resolving the contradiction between packing density and optical losses.
2Manufacturing precision
If high ion energy is used to increase compaction of coating material, then the packing density improves, but the risk of damage from high-energy ions increases
Solution Approach 1:
The patent changes the ionization energy parameter by introducing a second gas with lower ionization energy than the first gas in the plasma mixture. This enables effective compaction through ion bombardment while reducing the damage caused by high-energy ions, thus resolving the contradiction between packing density improvement and damage prevention.
3Reliability
If conventional sealing methods are used to protect optical elements from fluorine depletion, then radiation stability improves, but the technological complexity and cost increase
Solution Approach 1:
The patent changes the plasma process parameters by using a specific gas mixture composition where the second gas has lower ionization energy. This modifies the deposition process to inherently provide better radiation stability without requiring additional sealing layers or complex post-treatments, thus resolving the contradiction between radiation stability and technological complexity.
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 enables the deposition of coatings with high packing density and low absorption, enhancing the chemical, mechanical, and environmental stability of optical elements while minimizing damage from high-energy ions, thus improving the radiation resistance and longevity of optical components.
Implementation Method 1
The plasma is formed from a gas mixture comprising a first gas and a second gas, wherein the second gas has an ionization energy less than an ionization energy of the first gas
Data Source
AI summary
A method of forming a layer (3) on a substrate (2) made of a fluoridic material includes: depositing a coating material (9) on the substrate to form the layer and generating a plasma (12) to assist the deposition of the coating material. The plasma is formed from a gas mixture (14) containing a first gas (G) and a second gas (H), wherein the second gas has an ionization energy less than an ionization energy of the first gas, the first gas is a noble gas and the second gas is a further noble gas. An associated optical element includes: a substrate (2) composed of a fluoridic material, in particular a metal fluoride, wherein the substrate has a coating (18) having a layer (3) formed by the above method. An associated optical system, in particular for the DUV wavelength range, includes at least one such optical element.