EUV Mirror Reflectance via Cyano-Terminated Silicon
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Solution Overview
Problem
Existing extreme ultraviolet light condensation mirrors experience a decrease in reflectance due to blister formation between the multi-layer reflective film and the protective film, primarily caused by hydrogen radicals accumulating and forming hydrogen molecules, which reduce the mirror's ability to reflect EUV light effectively.
Innovation Solution
The use of an amorphous silicon layer with silicon atoms bonded to cyano radicals in the multi-layer reflective film, which terminates dangling bonds and prevents hydrogen radicals from forming blisters by increasing the binding energy, thereby maintaining reflectance and preventing blister generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional multi-layer reflective film is used, then the mirror can reflect EUV light, but blisters form between the reflective film and protective film due to hydrogen radical accumulation, causing reflectance to decrease
Solution Approach 1:
The patent converts the harmful effect of hydrogen radicals (which cause blistering) into a beneficial effect by using cyano radicals to terminate silicon dangling bonds. This prevents hydrogen radical accumulation and blister formation, thereby maintaining reflectance and converting a potential failure mode into a protective mechanism
Solution Approach 2:
The patent changes the chemical composition parameter of the amorphous silicon layer by introducing cyano radicals bonded to silicon atoms. This parameter change increases binding energy and prevents hydrogen radical accumulation, thereby eliminating blister formation while maintaining the reflective function
2Reliability
If the amorphous silicon layer contains silicon atoms with cyano radicals, then blister formation is prevented and reflectance is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by forming the cyano radical-modified amorphous silicon layer as the topmost layer of the multi-layer reflective film during the initial fabrication process. This preliminary modification of silicon dangling bonds prevents subsequent hydrogen radical accumulation and blister formation, eliminating the need for additional protective measures
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 reduces blister formation and maintains the reflectance of the EUV light condensation mirror by ensuring that hydrogen radicals are discharged rather than accumulating, thus enhancing the mirror's performance in reflecting extreme ultraviolet light.
Implementation Method 1
a layer on a most surface side in the multi-layer reflective film being the amorphous silicon layer containing a silicon atom bonded with a cyano radical
Implementation Method 2
a multi-layer reflective film provided on the substrate, formed by alternately stacking an amorphous silicon layer and a layer having a refractive index different from a refractive index of the amorphous silicon layer, and configured to reflect extreme ultraviolet light
Data Source
AI summary
An extreme ultraviolet light condensation mirror includes a substrate, and a multi-layer reflective film provided on the substrate, formed by alternately stacking an amorphous silicon layer and a layer having a refractive index different from a refractive index of the amorphous silicon layer, and configured to reflect extreme ultraviolet light, a layer on a most surface side in the multi-layer reflective film being the amorphous silicon layer containing a silicon atom bonded with a cyano radical.