Isocyanurate Anti-Reflective Coating for Photolithography
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Solution Overview
Problem
Conventional organic anti-reflective coating layers used in photolithography processes are unstable at high temperatures and suffer from issues like undercutting and notching due to optical interference effects, especially when using short-wavelength exposure light sources like ArF excimer lasers.
Innovation Solution
An isocyanurate compound with capped thiol groups and nitrogen, sulfur, and oxygen atoms is developed, which forms a stable organic anti-reflective coating layer with a high refractive index and superior etch rate, preventing undercutting and notching by controlling the extinction coefficient through capping materials, and is used in a composition including a crosslinking agent and acid generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isocyanurate compound with thiol groups is used to form an organic anti-reflective coating layer, then the coating layer achieves high refractive index and good etch rate, but the compound becomes unstable at room temperature or above due to disulfide bond formation
Solution Approach 1:
The harmful thiol groups (—SH) that cause instability through disulfide bond formation are removed from the isocyanurate compound structure. This extraction of the problematic functional group eliminates the source of compositional instability while preserving the beneficial optical and etching properties of the isocyanurate core structure.
Solution Approach 2:
The chemical structure of the isocyanurate compound is modified by changing the functional groups attached to the isocyanurate core. Instead of using thiol groups that form unstable disulfide bonds, the invention employs alternative functional groups that maintain high refractive index and etch rate while providing thermal stability at room temperature and above.
2Manufacturing precision
If short-wavelength exposure light (ArF 193 nm) is used to improve marginal resolution, then pattern resolution is enhanced, but optical interference effects increase causing undercutting and notching
Solution Approach 1:
The organic anti-reflective coating layer serves as an intermediary between the photoresist layer and the etching layer. This intermediate layer absorbs reflected exposure light through its high refractive index and appropriate thickness, preventing optical interference from reaching the photoresist pattern and causing undercutting or notching, while allowing the benefits of short-wavelength exposure to be realized.
3Reliability
If inorganic anti-reflective coating materials are used, then high absorptivity and etch rate are achieved, but complex and expensive apparatus such as vacuum evaporator or sputter device is required
Solution Approach 1:
The invention replaces expensive inorganic anti-reflective coating materials that require complex vacuum deposition equipment with an organic polymer-based coating that can be applied using simple spin-coating technology. The organic isocyanurate compound formulation achieves comparable or superior performance in absorptivity and etch rate while eliminating the need for costly vacuum evaporators, sputter devices, and other complex coating apparatus.
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 isocyanurate compound provides a stable and high-performance organic anti-reflective coating layer that maintains stability at high temperatures, improves pattern profiles, and enhances etch rates, effectively addressing the challenges of undercutting and notching in photolithography processes.
Implementation Method 1
a bottom anti-reflective coating layer (bottom anti-reflective coatings: BARCs) is conventionally formed between the etching layer and the photoresist layer to absorb the exposure light (reflected light)
Implementation Method 2
0.01 to 0.25 weight % of an acid generator
Data Source
AI summary
An isocyanurate compound for forming an organic anti-reflective coating layer, which has superior stability and etch rate at a high temperature, and which has a high refractive index, is represented by following Formula 1.In Formula 1, R is independently a hydrogen atom or a methyl group, R1 is independently a chain type or ring type saturated or unsaturated hydrocarbyl group of 1 to 15 carbon atoms containing 0 to 6 of hetero atoms, and R2 independently a chain type or ring type saturated or unsaturated hydrocarbyl group of 1 to 15 carbon atoms containing 0 to 15 of hetero atoms, wherein, R1 can have at least two bonding parts, and in the case that R1 has at least two bonding parts, the rest parts except R1 of the compounds represented by Formula 1 can connect to the R1 to form a polymer structure.