Acenaphthene-Substituted Positive Resist Composition for High Resolution Patterning
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Solution Overview
Problem
Current positive resist compositions face challenges in achieving high resolution, minimal edge roughness, and improved etching resistance, particularly in the context of microelectronic device manufacturing where pattern feature sizes are reducing, and high-energy radiation exposure is used, leading to issues with acid diffusion and sensitivity.
Innovation Solution
A chemically amplified positive resist composition is developed using a polymer with recurring units containing acenaphthene-substituted carboxyl groups, which suppresses acid diffusion and enhances dissolution contrast, etching resistance, and pattern profile quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the accelerating voltage is increased to improve resolution and reduce forward scattering, then the resolution and dimensional control are improved, but the sensitivity of the resist film is reduced
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, and by optimizing the ratio of basic compounds to photoacid generators. This allows the resist to maintain higher sensitivity even at increased accelerating voltages (50-100 keV), resolving the contradiction between resolution improvement and sensitivity loss
Solution Approach 2:
The patent uses composite resist formulations combining multiple polymer components (including polyhydroxystyrene, carboxyl-containing polymers, and acid-labile group-containing polymers) with specific photoacid generators and basic compounds. This composite approach enables the resist to achieve both high resolution at elevated accelerating voltages and maintained sensitivity through synergistic interactions among components
2Manufacturing precision
If the resist film thickness is reduced to improve resolution and prevent pattern collapse, then the resolution is improved, but the etching resistance is reduced
Solution Approach 1:
The patent modifies the chemical composition parameters of the resist film by incorporating polymers with specific functional groups (carboxyl groups, acid-labile groups) and optimizing the molecular weight distribution. These compositional changes enable thin resist films (50-200 nm) to maintain adequate etching resistance while achieving high resolution, as the specific chemical groups enhance the film's structural integrity and etch selectivity
Solution Approach 2:
The patent introduces acid-labile groups that undergo localized structural changes upon exposure and post-exposure baking. This creates local differences in solubility and etching behavior within the resist film, allowing thin films to maintain resolution while the exposed regions develop appropriate etching resistance characteristics for the specific patterning application
3Productivity
If chemically amplified resist compositions are used to improve sensitivity, then the sensitivity is improved, but the acid diffusion increases leading to reduced resolution
Solution Approach 1:
The patent introduces basic compounds as intermediaries that buffer and control acid diffusion in the chemically amplified resist system. The basic compounds (such as metal hydroxides or organic bases) neutralize excess acid and limit its diffusion distance, thereby maintaining the high sensitivity provided by chemical amplification while preventing resolution degradation from excessive acid spread
Solution Approach 2:
The patent optimizes the concentration ratio of basic compounds to photoacid generators and adjusts the pKa values of the basic compounds to match the exposure conditions. This parameter optimization ensures that acid diffusion is controlled to an appropriate extent while maintaining high sensitivity, achieving both improved productivity and manufacturing precision
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 exhibits high alkaline dissolution contrast, resolution, and minimal edge roughness, making it suitable for fine pattern formation in VLSIs and photomasks, while improving etching resistance and process adaptability.
Implementation Method 1
a polymer having carboxyl groups whose hydrogen is substituted by an acid labile group having the general formula (1)... which suppresses acid diffusion and enhances dissolution contrast
Implementation Method 2
chemically amplified positive resist composition... a remarkably high contrast of alkaline dissolution rate before and after exposure
Data Source
AI summary
A positive resist composition comprising as a base resin a polymer having carboxyl groups whose hydrogen is substituted by an acid labile group of acenaphthene structure exhibits a high contrast of alkaline dissolution rate before and after exposure, a high resolution, a good pattern profile and minimal LER after exposure, a significant effect of suppressing acid diffusion rate, and improved etching resistance.