Antireflective Coating Composition for Photolithography
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Solution Overview
Problem
Current antireflective coatings (ARCs) used in photolithography for semiconductor fabrication are inadequate in preventing exposure light reflection, especially at higher numerical apertures, leading to reduced resolution and pattern distortion due to insufficient absorption and intermixing with resist films.
Innovation Solution
A composition comprising polymers with specific recurring units and aromatic rings, applied as a bi-layer or graded coating to segregate vertically and achieve optimal absorption, reducing reflection and enhancing dry etching rates, thereby preventing pattern deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional single-layer ARC is used, then the coating process is simple, but reflection of exposure light cannot be fully suppressed especially at high NA
Solution Approach 1:
The patent divides the single-layer ARC into a multi-layer structure with a first layer (lower extinction coefficient) and a second layer (higher extinction coefficient). This segmentation allows each layer to perform different functions: the first layer provides base absorption while the second layer enhances reflection suppression at high NA conditions, resolving the contradiction between process simplicity and reflection control effectiveness.
Solution Approach 2:
The patent applies local quality by assigning different extinction coefficients to different layers: the first layer has a lower extinction coefficient (0.05-0.3) and the second layer has a higher extinction coefficient (0.1-0.5). This localized property differentiation optimizes light absorption at different depths, enabling effective reflection suppression at high numerical apertures while maintaining a manageable multi-layer structure.
2Object-affected harmful factors
If inorganic ARC materials are used, then reflection suppression is effective, but deposition equipment and complex processes are required
Solution Approach 1:
The patent replaces inorganic ARC materials (which require vacuum deposition equipment) with organic polymer-based ARC materials that can be applied using conventional spin-coating processes. This substitution eliminates the need for complex deposition equipment while achieving effective reflection suppression through the multi-layer polymer structure with controlled extinction coefficients.
Solution Approach 2:
The patent changes the material parameter from inorganic to organic polymer materials, which fundamentally alters the deposition method from vacuum-based physical vapor deposition to solution-based spin-coating. This parameter change enables the use of standard semiconductor fabrication equipment while maintaining effective reflection control through optimized polymer layer structures.
3Object-affected harmful factors
If organic ARC with high absorption is used, then reflection is reduced, but intermixing with resist film and diffusion occur
Solution Approach 1:
The patent applies local quality by positioning the high-absorption second layer adjacent to the resist film while the first layer with lower absorption is farther from the resist. This spatial arrangement ensures that the region closest to the resist has gentler absorption properties, reducing intermixing and diffusion, while the second layer provides the necessary reflection suppression at the substrate interface.
Solution Approach 2:
The patent uses composite material strategy by combining two different polymer materials with complementary properties: the first polymer provides a stable interface with the resist film and base absorption, while the second polymer provides enhanced absorption for reflection suppression. This composite structure achieves both reflection reduction and compositional stability by leveraging the strengths of each material in its optimal position.
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 solution effectively reduces substrate reflection and enhances dry etching rates, ensuring high-resolution pattern formation and preventing resist film slimming during etching.
Implementation Method 1
The invention provides a composition for forming an ARC... effective in preventing reflection of exposure light... comprising (A) at least one polymer... having an extinction coefficient... and (B) at least one polymer containing an aromatic ring and having an extinction coefficient
Implementation Method 2
A composition comprising polymers with specific recurring units and aromatic rings, applied as a bi-layer or graded coating to segregate vertically and achieve optimal absorption
Data Source
AI summary
A composition comprising (A) a polymer having an alcohol structure with plural fluorine atoms substituted at α- and α′-positions and having k=0.01-0.4 and (B) an aromatic ring-containing polymer having k=0.3-1.2 is used to form an antireflective coating. The ARC-forming composition can be deposited by the same process as prior art ARCs. The resulting ARC is effective in preventing reflection of exposure light in photolithography and has an acceptable dry etching rate.