EUV Reticle Capping Layer Sidewall Design
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Solution Overview
Problem
In extreme ultraviolet (EUV) exposure processes, reticles often suffer from electrical arcing due to uneven capping layer sidewalls, leading to defects and reduced durability, especially during cleaning processes where the capping layer can be partially removed or lifted off.
Innovation Solution
A reticle design featuring a multi-layer structure with a capping layer and an absorber layer, where the absorber layer covers the entire upper surface and sidewall of the capping layer, ensuring a vertical sidewall slope and preventing electrical arcing, and the absorber layer's thickness protects the capping layer during cleaning, enhancing reticle durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capping layer is formed with a conventional process, then the manufacturing process is simple, but the sidewall becomes uneven and protruding, causing electrical arcing and reduced reticle durability
Solution Approach 1:
The reticle structure is segmented into distinct functional layers: a capping layer for protection and an absorber layer for pattern definition. This segmentation allows each layer to be optimized independently - the capping layer can be designed with vertical sidewalls to prevent arcing, while the absorber layer provides the necessary optical absorption, thereby improving reliability without excessive complexity
Solution Approach 2:
The solution transitions from a conventional single-layer capping structure to a stacked two-layer structure (capping layer + absorber layer) with vertical sidewalls. This dimensional change in structure architecture enables the capping layer to maintain uniform thickness and vertical profiles, preventing the uneven sidewalls that cause electrical arcing, while the added absorber layer ensures proper optical function
2Reliability
If the capping layer sidewall is not vertical and protrudes, then the manufacturing process is simpler, but electrical arcing occurs during EUV exposure
Solution Approach 1:
The sidewall angle parameter is changed from conventional sloped profiles to vertical (90-degree) sidewalls. This parameter change in the capping layer geometry eliminates protruding edges that concentrate electrical fields, thereby preventing electrical arcing during EUV exposure while maintaining manufacturing feasibility through controlled deposition processes
3Reliability
If the capping layer is exposed during cleaning, then cleaning access is improved, but the capping layer is partially removed or lifted off, reducing durability
Solution Approach 1:
The absorber layer is formed as a preliminary protective structure over the capping layer before the reticle undergoes cleaning processes. This preliminary protective layer prevents direct exposure and potential damage to the capping layer during cleaning, thereby maintaining capping layer integrity and durability without complicating the manufacturing process
4Manufacturing precision
If the absorber layer covers the entire upper surface and sidewall of the capping layer, then pattern integrity is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
The absorber layer is applied with local quality differentiation - it completely covers the upper surface of the capping layer for optimal pattern definition, while also extending to cover the sidewall region. This localized variation in coverage ensures pattern integrity in critical areas without unnecessarily complicating the overall manufacturing process
Data Source
AI summary
A reticle for an apparatus for EUV exposure and a method of manufacturing a reticle, the reticle including a substrate including an edge region and a main region; a multi-layer structure on the main region and the edge region, a sidewall of the multi-layer structure overlying the edge region; a capping layer covering an upper surface and the sidewall of the multi-layer structure and at least a portion of the edge region of the substrate; and an absorber layer on the capping layer, the absorber layer covering an entire upper surface of the capping layer on the edge region of the substrate, wherein a stacked structure of the capping layer and the absorber layer is on an upper surface of the edge region of the substrate, and a sidewall of the stacked structure of the capping layer and the absorber layer is perpendicular to an upper surface of the substrate.