Chemically Amplified Negative Resist Composition for Lithography
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Solution Overview
Problem
Chemically amplified negative resist compositions with acid generators incorporated into the polymer face challenges in achieving high resolution and minimizing line edge roughness (LER) while forming fine feature size patterns, often resulting in bridge formation and scum in spaces, especially on substrates prone to undercutting.
Innovation Solution
A chemically amplified negative resist composition comprising a polymer with specific recurring units that generate acid upon high-energy radiation, combined with crosslinkers, to create crosslinks between polymer molecules, ensuring insolubility in alkaline developers and reducing LER, featuring recurring units of specific formulas (1) to (7) in a defined molecular percentage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If acid generators are incorporated into the polymer for chemically amplified negative resist composition, then sensitivity to high-energy radiation is improved, but line edge roughness increases and bridge formation occurs
Solution Approach 1:
The acid generator is segmented from the main polymer chain and incorporated as a specific recurring unit (formula 1) with controlled composition ratio (0.5-10 mol%). This segmentation allows the acid generator to be distributed uniformly throughout the polymer structure, improving sensitivity while controlling the extent of acid-catalyzed reactions to minimize LER and bridge formation.
Solution Approach 2:
The invention changes the chemical structure parameters of the acid generator unit by incorporating fluorine atoms and specific hydrocarbon groups (formula 1), and optimizes its composition ratio (0.5-10 mol%). These parameter changes tune the acid generation efficiency and diffusion characteristics, achieving high sensitivity while controlling LER.
2Strength
If crosslinkers are added to improve etch resistance, then etch resistance is improved, but pattern profile deteriorates due to undercutting
Solution Approach 1:
The crosslinking function is localized to specific recurring units (formulas 2-4) containing phenolic hydroxyl groups, which are distributed at controlled ratios (50-85 mol%). This local quality approach ensures crosslinking occurs at specific sites within the polymer chain, providing etch resistance while maintaining pattern profile integrity by preventing excessive undercutting.
Solution Approach 2:
The invention creates a composite polymer structure combining multiple functional units: acid generator units (formula 1), phenolic hydroxyl units (formulas 2-4), and other complementary units (formulas 5-7). This composite structure integrates etch resistance functionality with pattern fidelity, achieving both high etch resistance and controlled profile.
3Ease of operation
If phenolic units are used to improve solubility in alkaline developer, then dissolution performance is improved, but transmittance to ArF excimer laser light is lost
Solution Approach 1:
The invention uses phenolic hydroxyl-containing units (formulas 2-4) that provide excellent dissolution performance in alkaline developers. Although these units have limited transmittance to ArF excimer laser light, their primary function as dissolution-enhancing units is optimized, and the overall resist performance is achieved through the synergistic combination of multiple unit types in specific ratios.
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 and reduced LER, enabling controlled pattern formation with minimized undercutting, even on substrates prone to such issues, by optimizing the molecular structure and composition of the polymer and crosslinkers.
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
a basic compound is added for controlling the diffusion of the acid generated upon light exposure
Data Source
AI summary
A polymer comprising 0.5-10 mol% of recurring units having acid generating capability and 50-99.5 mol% of recurring units providing for dissolution in alkaline developer is used to formulate a chemically amplified negative resist composition. When used in a lithography process, the composition exhibits a high resolution and forms a negative resist pattern of a profile with minimized LER and undercut.