PAG-Immobilized Acid-Generating Layer for Lithography
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Solution Overview
Problem
As feature sizes in photolithography reduce, anisotropic acid diffusion leads to broadened feature size and line edge roughness, necessitating improved photoresists to enhance feature fidelity.
Innovation Solution
A method involving a substrate with an acid-generating layer comprising a polymer with recurring monomers and a surface adhesion group, and an acid-sensitive layer with minimal acid content, where the acid-generating layer is exposed to radiation to form a pattern, reducing line edge roughness and line width roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photoresist with blended PAG is used, then the method is simple to implement, but anisotropic acid diffusion causes broadened feature size and line edge roughness
Solution Approach 1:
The patent divides the traditional blended photoresist system into two separate functional layers: an acid-generating layer containing PAG-immobilized polymer and an acid-sensitive layer containing the polymer matrix. This segmentation allows each layer to perform its specific function independently, preventing anisotropic acid diffusion while maintaining manufacturing feasibility through sequential application and processing.
Solution Approach 2:
The acid-generating layer acts as an intermediary between the incident radiation and the acid-sensitive layer. It absorbs the radiation and generates acid in a controlled manner, which then diffuses uniformly into the acid-sensitive layer without the anisotropic diffusion problems of traditional blended systems. This intermediary structure enables precise pattern transfer while reducing line edge roughness.
2Productivity
If feature size is reduced, then higher density integration is achieved, but line edge roughness and feature broadening increase
Solution Approach 1:
The patent changes the physical and chemical parameters of the acid generation and diffusion process by using immobilized PAG in a separate layer. This results in more uniform acid concentration distribution and reduced anisotropic diffusion, enabling smaller feature sizes to be formed with acceptable line edge roughness and maintaining integration density improvements.
3Manufacturing precision
If additional photoresist layers are added to improve pattern transfer, then feature fidelity increases, but process complexity increases
Solution Approach 1:
The two-layer structure combines multiple functions into a unified system: the acid-generating layer provides both radiation absorption and acid generation, while the acid-sensitive layer provides both the polymer matrix and pattern definition capability. This multi-functional integration achieves superior pattern transfer without requiring additional separate photoresist layers or process steps.
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 allows for high-density PAG immobilization, mitigating anisotropic acid diffusion, achieving higher feature fidelity and conformal coatings on complex structures without the need for additional photoresist layers, thus improving pattern transfer and reducing process complexity.
Implementation Method 1
The acid-generating composition is heated to form an acid-generating layer
Implementation Method 2
at least a portion of the acid-sensitive layer is exposed to radiation
Data Source
AI summary
Materials and methods to immobilize photoacid generators on semiconducting substrates are provided. PAG-containing monomers are copolymerized with monomers to allow the polymer to bind to a surface, and optionally copolymerized with monomers to enhance solubility to generate PAG-containing polymers. The PAG-containing monomers can be coated onto a surface, where the immobilized PAGs can then be used to pattern materials coated on top of the immobilized PAGs, allowing direct patterning without the use of a photoresist, thereby reducing process steps and cost. The disclosed materials and processes can be used to produce conformal coatings of controlled thicknesses.