Positive Resist Composition with Acid-Suppressing Polymer
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Solution Overview
Problem
Current chemically amplified positive resist compositions face challenges in achieving high sensitivity, resolution, and minimal edge roughness, particularly as feature sizes reduce, due to issues with acid diffusion and sensitivity contrast, which are exacerbated by increased accelerating voltages in electron beam exposure systems.
Innovation Solution
A positive resist composition incorporating a polymer with recurring styrene units bonded to a CF3—C(OH)—R3 group, such as 1,1,1,3,3,3-hexafluoro-2-propanol, which suppresses acid diffusion by increasing the acidity of the hydroxy moiety when bonded to an ester group, thereby improving dissolution contrast and reducing edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the accelerating voltage is increased to reduce feature size, then resolution is improved, but sensitivity of the resist film decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the resist film by incorporating specific polymers with carboxyl groups and acid-labile groups, adjusting the molecular structure to optimize both sensitivity and resolution performance under high accelerating voltage conditions
Solution Approach 2:
The patent uses composite resist formulations combining multiple polymer components including poly(4-hydroxystyrene), poly(4-methoxystyrene), and copolymers with acid-labile groups, creating a composite material that balances sensitivity enhancement with resolution maintenance
2Manufacturing precision
If acid diffusion is suppressed to improve resolution, then manufacturing precision is improved, but sensitivity is reduced
Solution Approach 1:
The patent introduces acid-labile groups at specific locations within the polymer structure that selectively suppress acid diffusion in critical areas while maintaining overall sensitivity, creating localized functional zones within the resist material
Solution Approach 2:
The patent modifies the chemical parameters by incorporating carboxyl groups with specific pKa values and acid-labile groups that change the acid diffusion characteristics locally, allowing resolution improvement without sacrificing overall sensitivity
3Manufacturing precision
If post-exposure bake temperature or time is reduced to minimize acid diffusion, then resolution is improved, but sensitivity and contrast decrease drastically
Solution Approach 1:
The patent incorporates acid-labile groups that are pre-positioned in the polymer structure to suppress acid diffusion during the exposure process itself, eliminating the need for aggressive PEB condition reduction and maintaining sensitivity while achieving resolution
Solution Approach 2:
The acid-labile groups act as intermediary elements that mediate between the acid generation process and the final pattern formation, controlling acid diffusion in a way that preserves both sensitivity and contrast without requiring extreme PEB condition adjustments
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 resolution and minimal edge roughness, forming patterns of good profile and high sensitivity, making it suitable for micropatterning in VLSI and photomask fabrication.
Implementation Method 1
suppresses acid diffusion by increasing the acidity of the hydroxy moiety when bonded to an ester group
Data Source
AI summary
A positive resist composition is provided comprising a polymer comprising recurring styrene units having an ester group bonded to a CF3—C(OH)—R3 group (R3═H, CH3, or CF3) such as 1,1,1,3,3,3-hexafluoro-2-propanol and having a Mw of 1,000-500,000. The resist composition has a satisfactory effect of suppressing acid diffusion and a high resolution, and forms a pattern of good profile and minimal edge roughness after exposure.