Wet-Dry Bilayer Resist for Self-Aligned EUV Patterning
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Solution Overview
Problem
Conventional lithographic techniques face challenges in achieving accurate and reliable patterning, particularly with extreme ultraviolet (EUV) lithography, due to issues like image fidelity, line end variability, and the limitations of single-species photoresist films.
Innovation Solution
The use of a multilayer photoresist stack comprising a dry resist film deposited by vapor deposition and a wet resist film deposited by spin-on deposition, where the wet resist film is sensitive to EUV or UV radiation, enabling accurate and reliable EUV lithography by forming a self-aligned cut process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-species photoresist film is used for EUV lithography, then the process is simple, but image fidelity and line end accuracy deteriorate due to fuzzy ends and variability
Solution Approach 1:
The patent divides the photoresist system into two separate layers: a wet photoresist layer deposited by spin-on deposition and a dry photoresist layer deposited by vapor deposition. This segmentation allows each layer to perform specific functions - the wet layer provides good imaging and the dry layer provides sharp line ends - thereby resolving the contradiction between structural simplicity and manufacturing precision
Solution Approach 2:
The patent employs a composite photoresist structure combining two different photoresist materials with distinct properties. The wet photoresist and dry photoresist are layered together to create a composite system that leverages the advantages of both materials, achieving high image fidelity while eliminating fuzzy line ends, thus resolving the contradiction between device complexity and manufacturing precision
2Device complexity
If conventional single-layer photoresist is used, then the process is straightforward, but image fidelity deteriorates due to radiation sensitivity limitations
Solution Approach 1:
The patent segments the photoresist into two functional layers with different radiation sensitivities. The wet photoresist layer is optimized for UV or extreme UV exposure providing high image fidelity, while the dry photoresist layer provides additional radiation sensitivity enhancement. This segmentation resolves the contradiction by allowing each layer to contribute to image fidelity without requiring a single complex material
Solution Approach 2:
The composite photoresist structure combines two photoresist materials that respond differently to radiation. This composite approach enhances overall image fidelity by leveraging the radiation sensitivity characteristics of both materials, resolving the contradiction between maintaining simple processing and achieving high manufacturing precision
3Manufacturing precision
If a multilayer photoresist stack with wet and dry layers is used, then patterning accuracy improves, but process complexity increases
Solution Approach 1:
The patent uses segmentation to divide the photoresist into two distinct layers deposited by different methods (spin-on and vapor deposition). This segmentation enables independent optimization of each layer for specific patterning functions, achieving high patterning accuracy while managing complexity through modular layer design
Solution Approach 2:
The patent transitions from a single-layer to a multilayer photoresist structure, adding a vertical dimension to the photoresist system. This dimensional change allows for enhanced patterning accuracy through the combined effects of multiple layers, while the systematic approach to layer integration keeps the process complexity manageable
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 enhances the accuracy and reliability of EUV patterning by truncating fuzzy ends and achieving self-aligned cuts, thereby improving the fidelity and precision of microfabrication processes.
Implementation Method 1
a first layer of a wet photoresist deposited by spin-on deposition... sensitive to EUV or UV radiation
Implementation Method 2
a second layer of a dry photoresist deposited by vapor deposition
Data Source
AI summary
A method of patterning a substrate includes forming a multilayer photoresist stack on a substrate. The multilayer photoresist stack includes a first layer of a wet photoresist deposited by spin-on deposition, and a second layer of a dry photoresist deposited by vapor deposition. The first layer is positioned over the second layer. A first relief pattern is formed in the first layer by exposure to a first pattern of actinic radiation of a first wavelength and development of developable portions of the first layer using a first development process. The first relief pattern uncovers portions of the second layer. A multi-color layer of the first relief pattern is formed. The multi-color layer includes the wet photoresist and a third material that is different from the wet photoresist and the dry photoresist. A selective patterning process is executed for uncovered portions of one or two of the wet photoresist, the dry photoresist and the third material.