GaN Layer for EUV Mirror Substrate Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
EUV mirrors in microlithographic projection exposure apparatuses face radiation-induced structural alterations and impaired reflection properties due to the lack of suitable light-transmissive refractive materials, leading to geometric changes and aging effects in metallic and amorphous mirror substrates.
Innovation Solution
Incorporating a layer of gallium nitride (GaN), aluminum nitride (AlN), or aluminum gallium nitride (AlGaN) between the mirror substrate and the reflection layer stack, which acts as both a polishing and protection layer, utilizing nitrogen ion-assisted vapor deposition to maintain amorphous structure and high radiation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional polishing layers (e.g., amorphous silicon) are applied to improve polishing precision, then manufacturing precision is improved, but the layer construction becomes more complex and susceptible to radiation-induced structural alterations
Solution Approach 1:
The invention extracts and eliminates the need for additional polishing layers by endowing the protection layer with polishing capabilities. The protection layer is configured with specific physical properties (amorphous structure, controlled thickness, appropriate material composition) that enable it to serve dual functions: protecting the mirror substrate from radiation and providing a polishable surface, thereby removing the need for separate polishing layers.
Solution Approach 2:
The protection layer is designed to perform multiple functions simultaneously: it protects the mirror substrate from EUV radiation, provides a surface suitable for polishing to achieve required optical precision, and maintains structural stability under radiation loading. This multi-functionality eliminates the need for separate polishing layers and simplifies the overall layer construction.
2Reliability
If protection layers are added to protect mirror substrate from radiation, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the protection function and polishing function into a single integrated layer. The protection layer is designed with specific characteristics (amorphous structure, controlled thickness, appropriate material composition) that enable it to simultaneously provide radiation protection and serve as a polishing surface, thereby combining multiple functions into one layer and reducing overall structural complexity.
3Manufacturing precision
If multiple layers are used to achieve precise polishing, then manufacturing precision is improved, but the number of layers increases and structural stability under radiation decreases
Solution Approach 1:
The invention extracts and eliminates the need for additional polishing layers by endowing the protection layer with polishing capabilities. The protection layer is configured with specific physical properties (amorphous structure, controlled thickness, appropriate material composition) that enable it to serve dual functions: protecting the mirror substrate from radiation and providing a polishable surface, thereby removing the need for separate polishing layers.
Solution Approach 2:
The protection layer is designed to perform multiple functions simultaneously: it protects the mirror substrate from EUV radiation, provides a surface suitable for polishing to achieve required optical precision, and maintains structural stability under radiation loading. This multi-functionality eliminates the need for separate polishing layers and simplifies the overall layer construction.
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 gallium nitride layer effectively prevents radiation-induced structural changes, maintains reflection properties, and reduces thermal expansion differences, allowing for precise polishing and protection of the mirror substrate, potentially eliminating the need for additional polishing layers.
Implementation Method 1
the use of protection layers (for short: SPL="Substrate Protection Layer") has proved to be expedient, which can be produced from a material that absorbs the EUV light to a comparatively great extent
Implementation Method 2
mirrors are used as optical components for the imaging process. Such EUV mirrors have a mirror substrate and a reflection layer stack—constructed from a multiplicity of layer packets—for reflecting the electromagnetic radiation impinging on the optical effective surface
Implementation Method 3
utilizing nitrogen ion-assisted vapor deposition to maintain amorphous structure and high radiation resistance
Data Source
AI summary
A mirror (10, 20, 30, 40), more particularly for a microlithographic projection exposure apparatus, has an optical effective surface (10a, 20a, 30a, 40a), a mirror substrate (11, 21, 31, 41) and a reflection layer stack (14, 24, 34, 44) for reflecting electromagnetic radiation impinging on the optical effective surface (10a, 20a, 30a, 40a), wherein a layer (13, 23, 33, 43) composed of a group III nitride is arranged between the mirror substrate (11, 21, 31, 41) and the reflection layer stack (14, 24, 34, 44), wherein the group III nitride is selected from the group containing gallium nitride (GaN), aluminum nitride (AlN) and aluminum gallium nitride (AlGaN).