Polymer-Bound Acid Generator Chemistry for Negative Resist Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chemically amplified negative resist compositions face challenges with acid diffusion leading to degraded lithography performance, resist pattern collapse, and poor etching resistance, which are exacerbated by the miniaturization of resist patterns.
Innovation Solution
A polymer-bound acid generator using repeat units derived from a sulfonium salt containing an aromatic sulfonic acid anion with a vinyl-substituted aromatic ring is incorporated into the resist composition, providing high contrast, reduced line edge roughness (LER), improved etch resistance, and minimized development defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional acid generators are used in chemically amplified negative resist compositions, then lithography performance can be achieved, but acid diffusion occurs leading to degraded resolution and line edge roughness
Solution Approach 1:
The patent combines the acid generator function with the polymer backbone by incorporating onium salt groups directly into the polymer structure. This merging eliminates the need for separate acid generator molecules, thereby preventing acid diffusion while maintaining lithography performance. The onium salt groups are covalently bonded to the polymer, ensuring they remain localized during the exposure and development processes.
Solution Approach 2:
The polymer backbone acts as an intermediary that carries the onium salt groups. Instead of using free-standing acid generators that can diffuse, the polymer serves as a structured carrier that releases acid in a controlled manner at the exposure sites, mediating between the exposure light and the chemical amplification process while preventing harmful diffusion.
2Manufacturing precision
If thin film resist is used to achieve high resolution, then smaller patterns can be formed, but resist pattern collapse occurs due to reduced mechanical stability
Solution Approach 1:
The patent employs a composite polymer structure combining aromatic rings (for etch resistance and mechanical strength) with onium salt groups (for acid generation). This composite material approach allows thin film formation for high resolution while the aromatic components provide the necessary mechanical stability to prevent pattern collapse during processing.
Solution Approach 2:
The polymer structure is designed with local aromatic ring structures that provide enhanced mechanical strength and etch resistance at critical locations within the resist film. This local quality enhancement allows the overall film to remain thin for high resolution while specific regions provide the structural support needed to prevent collapse.
3Strength
If phenolic units are used in resist compositions for KrF excimer laser lithography, then high etching resistance is achieved, but strong absorption at 200 nm prevents use in ArF excimer laser lithography
Solution Approach 1:
The patent changes the optical parameters of the polymer by incorporating onium salt groups with appropriate absorption characteristics. While maintaining the aromatic structure for etch resistance, the onium salt component adjusts the overall absorption spectrum to allow transmissivity at ArF excimer laser wavelengths (193 nm), enabling use in advanced lithography processes.
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 polymer-bound acid generator achieves high resolution, reduced LER, enhanced etch resistance, and minimized development defects, enabling the formation of small-size patterns with improved stability and resistance to collapse.
Implementation Method 1
a polymer-bound acid generator which generates an acid having an adequate strength upon light exposure
Implementation Method 2
a crosslinker which causes the polymer to crosslink in the presence of the acid serving as a catalyst
Implementation Method 3
The aromatic ring serves as an etch resistant group
Data Source
AI summary
A polymer comprising repeat units having formula (A1) and repeat units having formula (A2) is provided. The acid generated therefrom has an adequate acid strength and reduced diffusion distance. A chemically amplified negative resist composition comprising the polymer as a polymer-bound acid generator has satisfactory organic solvent solubility and etch resistance.