EUV Mask Multilayer Structure for Reduced Wafer Neighboring Effects
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, existing masks face challenges with wafer neighboring effects due to damage and contamination, which affect the cleanliness and defectivity of the masks, leading to reduced manufacturing efficiency and quality.
Innovation Solution
The development of an EUV mask with a specific absorption composite structure and additional reflective multilayers, including a first and second reflective multilayer configuration, to minimize wafer neighboring effects by reducing reflection and enhancing image quality, and a method for manufacturing this mask involving multiple layer deposition and patterning processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reflective mask is used in EUV lithography, then the mask can be used for advanced lithography patterning, but the mask suffers from damage and contamination leading to wafer neighboring effects
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a substrate layer, a first reflective multilayer, an absorption layer, and a second reflective multilayer. Each layer performs a specific function, with the absorption layer positioned to prevent damage propagation to the substrate while the reflective multilayers maintain optical performance. This segmentation isolates the damage-prone absorption layer from the critical substrate, reducing wafer neighboring effects.
Solution Approach 2:
The mask employs composite material structures including alternating layers of high-refractive-index materials (e.g., molybdenum) and low-refractive-index materials (e.g., silicon) in the reflective multilayers, and composite absorption materials (e.g., tantalum boron nitride or tantalum boron oxynitride). These composite structures optimize both optical reflectivity and damage resistance, maintaining mask cleanliness while enabling advanced lithography patterning.
2Manufacturing precision
If the absorption layer is made thicker to improve pattern definition, then the absorption performance is enhanced, but the mask becomes more susceptible to damage and contamination
Solution Approach 1:
The first reflective multilayer acts as an intermediary between the substrate and the absorption layer, providing mechanical support and optical functionality while protecting the substrate from damage. The second reflective multilayer serves as an intermediary between the absorption layer and the wafer, preventing damage propagation to subsequent wafers. This intermediary structure allows for optimized absorption layer thickness without compromising mask durability.
Solution Approach 2:
The absorption layer thickness is optimized within a specific range (e.g., 5-50 nm) to achieve sufficient absorption performance while minimizing damage susceptibility. The composition parameters of the absorption material (e.g., stoichiometry of tantalum boron nitride) are adjusted to balance absorption efficiency and mechanical strength, reducing contamination and damage without sacrificing pattern definition.
3Reliability
If additional reflective multilayers are added to reduce wafer neighboring effects, then the mask cleanliness is improved, but the device complexity increases
Solution Approach 1:
The second reflective multilayer serves multiple functions simultaneously: it acts as a protective barrier against damage propagation to wafers, provides additional optical reflection to enhance pattern contrast, and serves as a structural support layer. This multi-functionality reduces the need for separate protective layers, managing device complexity while improving mask cleanliness and reducing wafer neighboring effects.
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 wafer neighboring effects, improves mask cleanliness, and enhances the manufacturing process efficiency by minimizing damage and contamination, resulting in higher-quality EUV masks for advanced lithography applications.
Implementation Method 1
forming a first reflective multilayer over a mask substrate... depositing a first absorption layer over the first reflective ML
Implementation Method 2
depositing a first absorption layer over the first reflective ML... the first absorption layer configured to reduce reflection
Implementation Method 3
forming an etch stop layer over the first absorption layer... the etch stop layer configured to prevent over-etching during patterning
Data Source
AI summary
A method for manufacturing a reticle is provided. The method includes forming a first reflective multilayer over a mask substrate. The method also includes forming a capping layer over the first reflective ML. The method further includes depositing a first absorption layer over the capping layer. In addition, the method includes depositing an etch stop layer over the first absorption layer. The method also includes forming a second reflective multilayer (ML) over the etch stop layer. The method further includes forming a second absorption layer over the second reflective ML. In addition, the method includes forming an opening through the second absorption layer and the second reflective ML until the etch stop layer is exposed. The method also includes etching the etch stop layer and the first absorption layer through the opening until the capping layer is exposed.