EUV Photo Mask Multilayer Absorber Structure for Neighboring Effect
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Solution Overview
Problem
In extreme ultraviolet (EUV) lithography, the neighboring effect causes corner portions of exposure areas to be over-exposed, leading to manufacturing challenges in creating precise patterns on semiconductor wafers.
Innovation Solution
A reflective EUV photo mask is manufactured with multiple absorption layers and adjust layers, including Mo/Si film pairs, to control light interference and absorption, reducing over-exposure by incorporating a black border pattern that reduces reflectivity and minimizes the neighboring effect during the EUV lithography process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional reflective mask is used in EUV lithography, then the mask structure is simple, but corner portions of exposure areas are over-exposed due to the neighboring effect
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a first absorber layer, a first adjust layer, a second absorber layer, and a second adjust layer. Each layer serves a specific function in controlling light interference and absorption, allowing precise compensation for the neighboring effect while maintaining overall structural organization.
Solution Approach 2:
Different layers are assigned different material compositions and optical properties to address specific local requirements. The absorber layers provide strong light absorption, while the adjust layers fine-tune the optical characteristics to eliminate over-exposure at corner portions, creating locally optimized properties throughout the mask structure.
2Manufacturing precision
If multiple absorption layers and adjust layers are incorporated to reduce the neighboring effect, then pattern transfer precision is improved, but the mask manufacturing process becomes more complex
Solution Approach 1:
The mask structure is designed with pre-calculated layer thicknesses and material compositions that are deposited in sequence during manufacturing. The first absorber layer, first adjust layer, second absorber layer, and second adjust layer are formed with specific parameters beforehand to achieve the desired optical compensation, simplifying the manufacturing process by eliminating the need for complex post-processing adjustments.
Solution Approach 2:
The optical properties of each layer are precisely controlled by adjusting parameters such as layer thickness, material composition, and refractive index. The first and second absorber layers have different optical densities, and the adjust layers are tuned to specific thicknesses to achieve constructive and destructive interference patterns that cancel the neighboring effect, allowing precise pattern transfer through parameter optimization rather than complex structural design.
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 the neighboring effect, allowing for more precise pattern transfer and improved manufacturing accuracy in EUV lithography, enhancing the production of semiconductor wafers with complex circuit designs.
Implementation Method 1
A reflective EUV photo mask is manufactured with multiple absorption layers and adjust layers, including Mo/Si film pairs, to control light interference and absorption
Implementation Method 2
A reflective EUV photo mask is manufactured with multiple absorption layers and adjust layers, including Mo/Si film pairs, to control light interference and absorption, reducing over-exposure by incorporating a black border pattern that reduces reflectivity
Data Source
AI summary
A reflective mask includes a substrate, a reflective multilayer disposed on the substrate, a capping layer disposed on the reflective multilayer, a first absorber layer disposed on the capping layer, a first multilayer disposed over the first absorber layer, a second absorber layer disposed on the first multilayer layer, and a second multilayer, which is an uppermost layer of the reflective mask, disposed over the second absorber layer.