Multilayer Underlayer Composition for Swelling-Resistant Lithography
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Solution Overview
Problem
In semiconductor IC device manufacturing, the bi-layer and tri-layer structures used in photolithography patterning processes face issues with materials penetrating the bottom layer, causing swelling and stress, which leads to delamination and deformation, negatively impacting the reproducibility and critical dimensions of patterned features.
Innovation Solution
The bottom layer is modified by incorporating polymers and cross-linking agents, with a higher concentration of cross-linking agents in the upper section to inhibit penetration by etching agents, and the use of specific monomers and catalysts to enhance cross-linking density, reducing swelling and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bottom layer is made thinner to improve resolution, then manufacturing precision improves, but the layer becomes more susceptible to penetration by etching agents causing swelling and delamination
Solution Approach 1:
The patent applies local quality by creating a gradient in cross-linking density within the bottom layer. The upper section has higher cross-linking density to resist etching agent penetration, while the lower section has lower density for better adhesion. This spatial variation in material properties allows the thin layer to maintain both resolution and stability.
Solution Approach 2:
The patent uses composite materials by combining polymers with cross-linking agents in a multi-component system. The cross-linked polymer network creates a composite structure that provides both mechanical stability and resistance to chemical penetration, enabling the bottom layer to function effectively at reduced thickness.
2Reliability
If cross-linking density is increased to reduce swelling, then layer stability improves, but the layer becomes more rigid and less adaptable to processing variations
Solution Approach 1:
The patent resolves this contradiction by applying different cross-linking densities to different regions. The upper section has high cross-linking density for swelling resistance, while the lower section maintains lower density for flexibility and adhesion. This local differentiation allows the layer to exhibit both stability and adaptability simultaneously.
Solution Approach 2:
The patent introduces dynamic adaptability through the gradient structure that can respond differently to various processing conditions. The less cross-linked lower section provides flexibility for processing variations, while the highly cross-linked upper section maintains dimensional stability during patterning operations.
3Ease of manufacture
If uniform cross-linking is applied throughout the bottom layer, then manufacturing simplicity is maintained, but penetration resistance is insufficient due to material homogeneity
Solution Approach 1:
The patent overcomes the limitation of uniform cross-linking by implementing spatially varying cross-linking density. The gradient from lower density at the bottom to higher density at the top provides enhanced penetration resistance where needed while maintaining manufacturing feasibility through controlled formulation and processing.
Solution Approach 2:
The patent applies parameter changes by varying the cross-linking density parameter throughout the layer thickness. This is achieved through controlled addition of cross-linking agents and processing conditions that create the gradient, transforming a uniform structure into a functionally optimized non-uniform structure.
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 modification improves the quality of the bottom layer during lithography patterning by reducing unwanted swelling and stress, enhancing the reproducibility and accuracy of patterned features.
Implementation Method 1
The bottom layer includes a polymer and a cross-linking agent. The cross-linking agent cross-links the polymer of the bottom layer.
Implementation Method 2
the modified cross-linking agent to rise within the uncrosslinked bottom layer such that the concentration gradient of the modified cross-linking agent within the bottom layer increases from a lower section of the bottom layer to an upper section of the bottom layer
Data Source
AI summary
A method includes providing a layered structure on a substrate, the layered structure including a bottom layer formed over the substrate and a photoresist layer formed over the bottom layer, exposing the photoresist layer to a radiation source, developing the photoresist layer, patterning the bottom layer and removing portions of the substrate through openings in the patterned bottom layer. In some embodiments, a middle layer is provided between the bottom layer and the photoresist layer. The material of the bottom layer includes at least one cross-linking agent that has been functionalized to decrease its affinity to other materials in the bottom layer.