Positive Resist Composition for Controlled Acid Diffusion Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chemically amplified resist compositions face challenges in forming small-size patterns with controlled acid diffusion, leading to issues such as inversely tapered profiles and pattern collapse during development, which affect resolution and uniformity in EB lithography.
Innovation Solution
A chemically amplified positive resist composition using an onium salt with a specific sulfonic acid anion and triarylsulfonium cation structure, combined with a base polymer, to control acid diffusion and enhance solvent solubility, resulting in patterns with reduced LER and improved CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acid generators are used in chemically amplified resist compositions, then exposure sensitivity is achieved, but acid diffusion occurs leading to poor resolution and pattern profile control
Solution Approach 1:
The patent introduces a specific onium salt as an intermediary substance that generates acid upon exposure. This acid generator acts as a mediator between the exposure energy and the polymer matrix, controlling acid diffusion through its molecular structure while enabling chemically amplified dissolution. The onium salt structure allows controlled acid generation that prevents harmful acid diffusion to adjacent unexposed regions, thereby improving resolution.
Solution Approach 2:
The patent changes the chemical parameters of the acid generator by selecting a specific onium salt with particular molecular characteristics. This parameter change in the acid generating system controls the diffusion behavior of the generated acid, reducing its harmful spread while maintaining sufficient reactivity for pattern formation. The specific structural parameters of the onium salt dictate the acid diffusion characteristics.
2Ease of manufacture
If base polymer with acid-labile groups is used, then pattern dissolution after exposure is enabled, but inversely tapered profiles and pattern collapse occur during development
Solution Approach 1:
The patent applies local quality by using a base polymer with specifically designed acid-labile groups that are strategically positioned in the molecular structure. These groups are located at specific sites within the polymer chain, enabling localized dissolution response to acid exposure. This localized chemical modification allows controlled pattern dissolution while maintaining structural integrity of non-exposed regions, preventing profile inversion and collapse.
Solution Approach 2:
The patent creates a composite resist system combining the onium salt acid generator with a base polymer containing acid-labile groups. This composite material integrates the acid generation function with the controlled dissolution function, where the interaction between the generated acid and the acid-labile groups produces the desired pattern formation while avoiding harmful side effects like profile inversion.
3Productivity
If high sensitivity resist film is used for EB lithography, then throughput is maintained, but stability of exposed portion in vacuum deteriorates over time
Solution Approach 1:
The patent implements preliminary action by designing the onium salt and base polymer combination to undergo immediate and complete chemical reaction upon exposure. The acid generated from the onium salt instantly triggers dissolution of the acid-labile groups in the base polymer, creating a stable exposed pattern before any time-dependent degradation can occur. This preliminary chemical transformation locks in the pattern stability.
Solution Approach 2:
The patent changes the temporal parameters of the resist response by optimizing the reactivity of the onium salt and the sensitivity of the acid-labile groups. This parameter optimization ensures that the chemical transformation occurs rapidly and completely during or immediately after exposure, eliminating time-dependent instability in the exposed portions while maintaining high sensitivity for throughput.
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 high-resolution patterns with rectangular profiles and improved stability, effectively addressing the challenges of acid diffusion and profile inversion in EB and EUV lithography.
Implementation Method 1
acid-catalyzed chemically amplified resist compositions... High-energy radiation such as UV, deep-UV or EB is used as the energy source for exposure... the EB lithography, which is utilized as the ultra-fine microfabrication technique
Implementation Method 2
Acid-catalyzed chemically amplified resist compositions... (B) a base polymer containing a polymer adapted to be decomposed under the action of acid to increase its solubility in alkaline developer
Implementation Method 3
One outstanding problem is the diffusion of acid, which has a significant impact on the resolution of a chemically amplified resist film... acid diffusion is controlled
Data Source
AI summary
An onium salt consisting of a sulfonic acid anion having an aromatic sulfonic acid structure substituted with an aromatic ring-containing hydrocarbyl group and a triarylsulfonium cation containing iodine and fluorine generates an acid with limited diffusion. A chemically amplified positive resist composition comprising the onium salt as an acid generator and a polymer adapted to be decomposed under the action of acid to increase its solubility in alkaline developer is processed by lithography to form a pattern of rectangular profile.