Silicon Resist Underlayer Composition for Low-LWR Fine Patterning
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Solution Overview
Problem
The challenge lies in forming ultrafine patterns with improved LWR and CDU while maintaining appropriate etching rates in multilayer resist methods, as existing photoresist compositions face issues with resolution, pattern collapse, and incomplete etching selectivity, particularly in advanced lithography techniques like ArF immersion and EUV lithography.
Innovation Solution
A silicon-containing sulfonium salt compound, represented by a specific general formula, is added to a composition for forming a silicon-containing resist underlayer film, acting as a curing catalyst and enhancing the affinity with silicon polymers to suppress diffusion, thereby improving LWR and CDU, and providing a suitable etching rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the photoresist film is thinned to improve resolution for miniaturized patterns, then resolution performance is improved, but etching resistance deteriorates
Solution Approach 1:
The patent divides the single-layer resist system into a multilayer resist system consisting of an upper resist layer and a lower resist layer. The upper resist layer (thickness: 5-50 nm) provides resolution for miniaturized patterns, while the lower resist layer (thickness: 50-200 nm) provides etching resistance. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent adds a vertical dimension by introducing a lower resist layer beneath the upper resist layer. This creates a layered structure where the upper layer handles pattern formation and the lower layer handles etching protection, effectively adding a new dimension to the resist system architecture to simultaneously achieve high resolution and high etching resistance.
2Manufacturing precision
If the photoresist film thickness is reduced to improve resolution, then resolution is improved, but pattern collapse occurs during development
Solution Approach 1:
The patent segments the resist film into an upper resist layer (5-50 nm) and a lower resist layer (50-200 nm). The upper layer provides the necessary resolution for miniaturized patterns while the lower layer provides mechanical support during development, preventing pattern collapse. This segmentation allows the thin upper layer to achieve high resolution while the thicker lower layer maintains structural integrity.
3Manufacturing precision
If a resin with small light absorption is selected to improve resolution at shorter wavelengths, then resolution is improved, but etching rate becomes too high
Solution Approach 1:
The patent segments the resist system into two layers with different material compositions and functions. The upper resist layer uses a resin with small light absorption (e.g., novolac resin, polyhydroxystyrene, or aliphatic polycyclic skeleton resin) to achieve high resolution. The lower resist layer uses a different resin composition optimized for appropriate etching rate control. This segmentation allows independent optimization of optical properties and etching properties.
Solution Approach 2:
The patent applies local quality by using different resin compositions in different regions (layers) of the resist system. The upper layer uses resins optimized for optical performance (small light absorption), while the lower layer uses resins optimized for etching performance (controlled etching rate). Each layer has locally optimized properties suitable for its specific function.
4Strength
If a silicon-containing resist middle layer film is used to provide etching resistance, then etching resistance is improved, but incomplete removal causes residues that defect the substrate
Solution Approach 1:
The patent carefully controls the thickness parameter of the lower resist layer (50-200 nm) and adjusts the etching conditions to achieve complete removal without residues. The silicon-containing lower resist layer provides sufficient etching resistance during substrate processing, and by optimizing the thickness and etching parameters, complete removal is achieved without causing pattern transfer defects.
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 silicon-containing resist underlayer film exhibits excellent dry etching selectivity, reduces pattern collapse, and facilitates precise pattern transfer with minimal residue, enabling high-yield formation of fine patterns on semiconductor devices.
Implementation Method 1
A silicon-containing sulfonium salt compound... acting as a curing catalyst
Implementation Method 2
enhancing the affinity with silicon polymers to suppress diffusion
Data Source
AI summary
The present invention is a silicon-containing sulfonium salt compound represented by the following general formula (A-1). The present invention provides: a composition for forming a silicon-containing resist underlayer film capable of forming a silicon-containing resist underlayer film that has an appropriate etching rate in multilayer resist method and can improve LWR and CDU of an ultrafine pattern; a silicon-containing sulfonium salt compound contained in the composition; and a patterning process using the composition.