Chemically Amplified Resist Composition for High-Resolution Patterning
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Solution Overview
Problem
Current resist compositions face challenges in achieving high sensitivity, resolution, and minimal edge roughness for microelectronic device manufacturing, particularly as feature sizes reduce, due to issues with acid diffusion and sensitivity tradeoffs in electron beam exposure.
Innovation Solution
A chemically amplified positive resist composition incorporating a polymer with recurring units derived from hydroxyphenyl methacrylate substituted with acyl, acyloxy, or alkoxycarbonyl groups, which suppresses acid diffusion and enhances sensitivity and resolution while maintaining minimal edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the accelerating voltage of the electron gun is increased to enable further size reduction, then the resolution and dimensional control are improved, but the sensitivity of the resist film becomes lower
Solution Approach 1:
The patent changes the chemical composition parameters of the resist film by introducing a polymer with specific recurring units containing carboxyl or phenolic hydroxyl groups substituted with acid labile groups. This chemical parameter change enables the resist to become more sensitive to electron beam exposure, allowing high-resolution patterning even at high accelerating voltages where conventional resists would show reduced sensitivity.
Solution Approach 2:
The patent uses a composite polymer structure combining multiple functional groups (carboxyl/phenolic hydroxyl groups, acid labile groups, and hydroxyphenyl methacrylate units) within a single polymer chain. This composite material approach creates a resist film that simultaneously achieves high sensitivity through acid generation, high resolution through controlled acid diffusion, and good solubility contrast for pattern formation.
2Productivity
If chemically amplified resist compositions are used to enhance sensitivity and contrast, then the sensitivity is improved, but acid diffusion causes image blurring that reduces resolution
Solution Approach 1:
The patent modifies the acid diffusion parameter by incorporating acid labile groups that can be cleaved by generated acid, creating localized chemical changes that limit acid migration. The specific substitution of carboxyl or phenolic hydroxyl groups with acid labile groups creates a chemical environment that suppresses unwanted acid diffusion while maintaining the sensitivity-enhancing effects of chemical amplification.
Solution Approach 2:
The acid labile groups act as intermediary elements that mediate between the generated acid and the polymer matrix. These groups serve as acid traps or acid catalysts for deprotection reactions, localizing the acid effect and preventing it from diffusing freely through the resist film, thereby maintaining resolution while preserving sensitivity enhancement.
3Manufacturing precision
If the temperature and/or time of post-exposure baking is reduced to minimize acid diffusion, then the resolution is improved, but the sensitivity and contrast are drastically reduced
Solution Approach 1:
The patent changes the chemical reactivity parameters of the resist by incorporating acid labile groups that are highly sensitive to acid catalysis. This chemical modification allows the deprotection and dissolution processes to proceed efficiently at lower temperatures and shorter times, thereby maintaining high sensitivity and contrast while minimizing acid diffusion during the reduced PEB period.
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, suitable for micropatterning in VLSI and photomask fabrication, with improved sensitivity and reduced film thickness loss during alkaline development.
Implementation Method 1
a polymer comprising recurring units having a carboxyl and/or phenolic hydroxyl group whose hydrogen is substituted by an acid labile group, and recurring units having the general formula (1)... which suppresses acid diffusion
Implementation Method 2
the exposure system for mask manufacturing made a transition from the laser beam exposure system to the EB exposure system... high-energy radiation of very short wavelength such as electron beam (EB)
Implementation Method 3
improved dissolution contrast... control of acid diffusion is also important... with improved sensitivity and reduced film thickness loss during alkaline development
Data Source
AI summary
A polymer is obtained from copolymerization of a unit having a carboxyl and/or phenolic hydroxyl group substituted with an acid labile group with a hydroxyphenyl methacrylate unit having one acyl, acyloxy or alkoxycarbonyl group. The polymer is useful as a base resin in a positive resist composition. The resist composition comprising the polymer is improved in contrast of alkali dissolution rate before and after exposure, acid diffusion control, resolution, and profile and edge roughness of a pattern after exposure.