Iodized Phenol Sulfonium Resist for Resolution and Sensitivity
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Solution Overview
Problem
As feature sizes in microelectronic devices reduce, image blurs due to acid diffusion become a significant issue, leading to challenges in achieving high sensitivity, resolution, and uniformity in pattern formation.
Innovation Solution
A positive resist composition is developed using a base polymer with repeat units having a sulfonium salt structure of an iodized phenol compound, which minimizes acid diffusion and enhances physical and dissolution contrast, thereby improving sensitivity, resolution, and dimensional uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is suppressed by reducing PEB temperature and time, then resolution is improved, but sensitivity and contrast are drastically reduced
Solution Approach 1:
The patent introduces a polymer-bound acid generator as an intermediary substance that generates acid locally at the exposure site rather than allowing bulk acid diffusion. This mediator confines the acid generation to the exposed regions, enabling resolution improvement without sacrificing sensitivity, as the acid is generated precisely where needed during the PEB process.
Solution Approach 2:
The patent changes the chemical parameters of the resist composition by incorporating a polymer with embedded acid generator groups. This parameter change transforms the acid diffusion mechanism from bulk diffusion to localized generation, allowing the system to achieve both high resolution and maintained sensitivity even with reduced PEB temperature and time.
2Manufacturing precision
If acid diffusion is suppressed to improve resolution, then edge roughness is reduced, but dissolution contrast is insufficient
Solution Approach 1:
The patent employs a composite polymer structure combining the acid generator function with specific polymer chains that provide dissolution contrast. The composite material integrates both functions: the polymer backbone provides structural integrity and dissolution characteristics, while the embedded acid generator units provide localized acid generation, achieving both low edge roughness and high dissolution contrast.
3Manufacturing precision
If a polymer-bound acid generator is used to suppress acid diffusion, then resolution is improved, but the polymer structure becomes more complex
Solution Approach 1:
The patent segments the polymer structure into functional units: repeating monomer units with embedded acid generator groups. This segmentation allows the complex function of acid generation to be distributed across multiple simple, identical units along the polymer chain, making the overall structure more manageable and easier to synthesize while maintaining the resolution-improving function.
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 resist composition achieves high sensitivity and resolution while reducing edge roughness and dimensional variation, making it suitable for small-size pattern formation in VLSIs and photomasks.
Implementation Method 1
a base polymer comprising repeat units having a sulfonium salt structure of an iodized phenol compound
Data Source
AI summary
The positive resist composition comprises a base polymer comprising repeat units (a) having a sulfonium salt structure of an iodized phenol compound. The positive resist composition comprising a base polymer comprising repeat units having a sulfonium salt structure of an iodized phenol exhibits a high sensitivity and resolution, and forms a pattern of satisfactory profile with reduced edge roughness and dimensional variation.