Photosensitive Composition for Immersion Lithography
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Solution Overview
Problem
Current chemical amplification resist compositions used in semiconductor manufacturing and photo-fabrication processes face challenges in achieving good line edge roughness, exposure latitude, and contrast sensitivity, especially when subjected to immersion exposure, where the resist layer decomposes and contaminants can adversely affect the immersion liquid.
Innovation Solution
A photosensitive composition is developed that includes a compound capable of generating an organic acid upon irradiation, specifically a sulfonium or iodonium salt, combined with a resin that decomposes in an alkali developing solution and optionally includes additional acid generators or surfactants, to enhance solubility and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemical amplification resist compositions are used, then basic pattern formation is achieved, but line edge roughness and exposure latitude are insufficient
Solution Approach 1:
The patent uses a composite resin system combining poly(hydroxystyrene) with specific alicyclic hydrocarbon structures and carboxyl-containing groups. This composite approach allows simultaneous optimization of line edge roughness through the alicyclic structure and exposure latitude through the carboxyl groups that enhance acid diffusion and reaction efficiency.
Solution Approach 2:
The patent modifies the chemical parameters of the resist composition by incorporating specific compounds with controlled acid generation characteristics. The use of compounds generating carboxylic acids with pKa values in a specific range (3-7) optimizes the balance between sufficient deprotection reaction and controlled solubility change, improving both line edge roughness and exposure latitude.
2Measurement precision
If immersion exposure is performed to enhance resolution, then pattern resolution is improved, but the resist layer decomposes and contaminants affect the immersion liquid
Solution Approach 1:
The patent converts the potential harm of resist decomposition into a benefit by using compounds that generate stable carboxylic acids upon irradiation. These acids promote controlled deprotection reactions without causing unwanted decomposition, and the resulting reaction products are designed to be soluble and non-contaminating to the immersion liquid.
Solution Approach 2:
The patent introduces carboxylic acid groups as intermediary species that mediate between the generated protons and the polymer chains. These carboxylic acids act as controlled catalysts for the deprotection reaction, preventing direct harsh acid attack on the resist structure that would cause decomposition and contamination.
3Productivity
If resins with aromatic groups are used for KrF exposure, then good sensitivity and resolution are achieved, but absorption is large at 193 nm for ArF laser
Solution Approach 1:
The patent applies local quality by incorporating aromatic-like alicyclic structures (such as adamantyl groups) that provide localized electron density and bonding characteristics similar to aromatic rings, enabling good sensitivity without the extended conjugation that causes strong 193 nm absorption. The alicyclic structures provide the desired local electronic properties without the global aromatic absorption characteristics.
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 improves line edge roughness, exposure latitude, and contrast sensitivity, while maintaining performance in immersion exposure by preventing decomposition and contamination issues, thus ensuring better pattern formation and resist stability.
Implementation Method 1
a compound capable of generating an organic acid upon irradiation with actinic ray or radiation
Implementation Method 2
a resin capable of decomposing by the action of an acid to increase solubility in an alkali developing solution
Data Source
AI summary
A photosensitive composition containing a compound having a specific structure as described in the specification, a pattern-forming method using the photosensitive composition and the compound having a specific structure used in the photosensitive composition.