Silver Interconnect Patterning with Gamma-Ray Seed Formation
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Solution Overview
Problem
Current photolithography processes using extreme ultraviolet (EUV) light face challenges with non-uniform illumination due to unstable high power sources, leading to size variations in patterned features, and the use of copper in interconnects limits further reduction in feature size due to its grain size.
Innovation Solution
The method employs gamma ray radiation to lithographically pattern a light-sensitive silver precursor layer, reducing silver ions to silver metal and forming silver seed structures, which can be used as metal electrodes or etch masks, offering better resolution and uniformity compared to EUV lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EUV light is used for photolithography, then resolution is improved, but illumination uniformity deteriorates due to unstable high power sources
Solution Approach 1:
The patent replaces the mechanical/optical EUV light source system with a gamma ray radiation source. This substitution eliminates the illumination uniformity problems associated with EUV sources while maintaining or improving resolution capability for patterning the silver precursor layer.
Solution Approach 2:
The patent changes the wavelength parameter of the radiation source from EUV range to gamma ray range. This parameter change enables both high resolution patterning and stable, uniform illumination since gamma ray sources do not suffer from the same stability issues as high power EUV sources.
2Reliability
If copper is used in interconnects, then electrical conductivity is improved, but feature size reduction is limited due to grain size
Solution Approach 1:
The patent changes the material parameter from copper to silver in the interconnect structures. Silver has both superior electrical conductivity and the ability to be patterned at smaller dimensions, thus resolving the contradiction between maintaining good conductivity and enabling further feature size reduction.
3Productivity
If feature size is reduced, then integration density is improved, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent replaces the EUV photolithography system with gamma ray lithography. This substitution enables precise patterning at smaller feature sizes with better uniformity, thus allowing higher integration density to be achieved while maintaining manufacturing precision.
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
This approach improves the resolution and uniformity of patterned features, allowing for further reduction in feature sizes and enhancing the integration density of semiconductor devices, while also providing a more stable and efficient light source.
Implementation Method 1
exposing portions of the silver precursor layer to a radiation. The radiation causes a reduction of silver ions in the irradiated portions of the silver precursor layer
Data Source
AI summary
A method for forming a semiconductor structure is provided. The method includes depositing a hard mask layer over a substrate. The method further includes depositing a silver precursor layer over the hard mask layer. The method further includes exposing portions of the silver precursor layer to a radiation, the radiation causing a reduction of silver ions in the irradiated portions of the silver precursor layer. The method further includes removing non-irradiated portions of the silver precursor layer, resulting in a plurality of silver seed structures.