Negative Resist Composition Alkylthio Group LER Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current negative resist compositions face challenges in achieving high sensitivity, low line edge roughness (LER), high throughput, and minimizing substrate poisoning, especially when forming patterns with feature sizes of 0.1 µm or less, and fail to fully address the undercut problem when used on substrates like chromium oxynitride.
Innovation Solution
A chemically amplified negative resist composition is developed, comprising a base polymer with a weight average molecular weight of 1,000 to 2,500, an acid generator, and a nitrogen-containing basic component, where the base polymer includes recurring units with an alkylthio group and is synthesized using a sulfur compound as a chain transfer agent to reduce molecular weight and enhance acid generation efficiency, thereby improving sensitivity and reducing LER.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a chemically amplified negative resist composition is used to achieve high sensitivity and fine pattern formation, then sensitivity and resolution are improved, but line edge roughness (LER) increases and substrate poisoning occurs
Solution Approach 1:
The patent changes the molecular weight parameter of the base polymer to a specific range (1,000 to 2,500) and introduces alkylthio groups at controlled ratios (0.1 to 10 mol%) to optimize the balance between sensitivity and LER. This parameter optimization allows the resist to achieve high sensitivity while maintaining smooth line edges by controlling acid diffusion and polymer crosslinking behavior
Solution Approach 2:
The patent creates a composite resist system combining a specific base polymer with alkylthio groups, an acid generator, and a basic compound. This composite formulation works synergistically where the alkylthio groups modulate acid diffusion, the base polymer provides structural integrity, and the basic compound controls substrate interaction, collectively reducing LER while maintaining high sensitivity
2Measurement precision
If the molecular weight of the base polymer is reduced to improve sensitivity and reduce LER, then sensitivity and pattern quality are improved, but etch resistance decreases
Solution Approach 1:
The patent optimizes the molecular weight parameter to a specific range (1,000 to 2,500) rather than simply minimizing it. This controlled reduction improves sensitivity and LER while the lower molecular weight enables more effective crosslinking through the acid generator, actually enhancing etch resistance through improved network formation rather than decreasing it
Solution Approach 2:
The composite resist system compensates for potential etch resistance reduction through synergistic interactions: the alkylthio groups enhance crosslinking efficiency, the basic compound provides additional structural support, and the optimized polymer architecture creates a denser crosslinked network that maintains high etch resistance despite lower molecular weight
3Manufacturing precision
If a chemically amplified negative resist composition is used on chromium oxynitride substrates to achieve fine patterns, then resolution is improved, but undercut problem worsens
Solution Approach 1:
The basic compound in the resist composition acts as an intermediary between the acid generator and the chromium oxynitride substrate. It buffers the acid diffusion at the substrate interface, preventing the acid from attacking the substrate and causing undercut profiles, while still allowing sufficient acid diffusion to achieve the desired crosslinking and fine pattern resolution
Solution Approach 2:
The patent optimizes the ratio of basic compound to acid generator and controls the molecular weight and functional group content of the base polymer to precisely regulate acid diffusion distance. This parameter control allows the resist to achieve fine resolution through adequate crosslinking while the basic compound limits excessive acid penetration that would cause undercutting at the substrate interface
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 achieves a higher sensitivity and minimal LER, enabling the formation of fine patterns without collapse, and effectively mitigates the undercut problem on substrates like chromium oxynitride, while maintaining high etch resistance and throughput.
Implementation Method 1
an acid generator which is decomposed to generate an acid upon exposure to light
Implementation Method 2
a crosslinker which causes the polymer to crosslink in the presence of the acid serving as a catalyst
Implementation Method 3
synthesized using a sulfur compound as a chain transfer agent to reduce molecular weight
Data Source
AI summary
A negative resist composition comprises a base polymer comprising recurring units having an alkylthio group and having a Mw of 1000-2500, an acid generator, and a basic component, typically an amine compound containing a carboxyl group, but not active hydrogen. A 45-nm line-and-space pattern with a low value of LER can be formed.