Silicon Resist Underlayer Composition for Ultrafine Pattern Etching
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Solution Overview
Problem
Existing photoresist compositions face challenges in achieving high resolution and etching resistance while maintaining pattern integrity, particularly in ultrafine patterns, leading to issues like pattern collapse and poor edge roughness (LWR) and dimension uniformity (CDU) during substrate processing.
Innovation Solution
A silicon-containing sulfonium salt compound is used as a curing catalyst in a composition for forming a silicon-containing resist underlayer film, which enhances etching selectivity and suppresses diffusion into the upper resist layer, improving LWR and CDU, and is combined with a thermally crosslinkable polysiloxane to achieve appropriate etching rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photoresist film thickness is reduced to maintain pattern integrity during miniaturization, then pattern collapse is prevented, but etching resistance deteriorates
Solution Approach 1:
The invention 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 pattern definition with high resolution, while the lower resist layer (thickness: 50-200 nm) provides etching resistance. This segmentation allows each layer to be optimized for its specific function, resolving the contradiction between maintaining pattern integrity and ensuring sufficient etching resistance during miniaturization.
Solution Approach 2:
The invention transitions from a single-dimensional (single-layer) resist structure to a multi-dimensional (multilayer) resist structure. By adding the vertical dimension of layering, the system can simultaneously achieve thin upper layer for high-resolution patterning and thick lower layer for adequate etching resistance, effectively resolving the contradiction that cannot be solved within a single-layer constraint.
2Measurement precision
If a resin with small light absorption is used to improve resolution, then resolution performance is improved, but etching resistance becomes weak
Solution Approach 1:
The invention applies different material properties to different layers: 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, while the lower resist layer uses a silicon-containing resin to provide strong etching resistance. This local differentiation of material properties allows each layer to excel at its primary function, resolving the contradiction between resolution and etching resistance.
Solution Approach 2:
The invention creates a composite multilayer resist structure combining different resin materials with complementary properties. The upper layer uses organic resins optimized for light exposure and resolution, while the lower layer uses silicon-containing resins optimized for etching resistance. This composite approach allows the system to simultaneously achieve high resolution and strong etching resistance, which cannot be achieved with a single material.
3Manufacturing precision
If a silicon-containing resist middle layer film is used to provide etching resistance, then etching resistance is improved, but removal difficulty increases
Solution Approach 1:
The invention carefully controls the thickness parameter of the silicon-containing lower resist layer to be 50-200 nm, which is sufficient to provide the required etching resistance but thin enough to allow complete removal without excessive processing time. Additionally, the invention selects silicon-containing resins with specific chemical properties that enable effective removal by fluorine-based or alkaline etching liquids, thus resolving the contradiction between providing adequate etching resistance and enabling easy removal.
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 composition allows for the formation of ultrafine patterns with improved LWR and CDU, enabling high-yield pattern transfer to substrates with minimal residue and defect formation, particularly suitable for semiconductor devices.
Implementation Method 1
A silicon-containing sulfonium salt compound is used as a curing catalyst in a composition for forming a silicon-containing resist underlayer film
Implementation Method 2
combined with a thermally crosslinkable polysiloxane to achieve appropriate etching rates
Implementation Method 3
combined with a thermally crosslinkable polysiloxane to achieve appropriate etching rates
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.