Polymer-Bound Acid Generator for Lithography Resolution
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Solution Overview
Problem
As microelectronic devices approach the diffraction limit, the reduction in pattern feature size leads to lower light contrast, increased line width roughness (LWR), and critical dimension uniformity (CDU) issues due to acid diffusion and segregation in resist films, making it challenging to achieve high sensitivity and resolution simultaneously.
Innovation Solution
A resist composition featuring a polymer with recurring units derived from sulfonium or iodonium salts having a polymerizable unsaturated bond and an iodine atom in the linker between the unsaturated bond and fluorosulfonic acid, which reduces acid diffusion and enhances sensitivity, LWR, and CDU by promoting uniform acid generation and dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the resist film thickness is reduced to comply with size reduction progress, then the pattern feature size can be reduced, but the line width roughness (LWR) becomes greater
Solution Approach 1:
The patent changes the chemical parameters of the resist system by introducing a polymer-bound acid generator with specific structural characteristics (fluorinated sulfonic acid groups, specific molecular weight range) to modify acid diffusion behavior and generation kinetics, thereby improving LWR without increasing film thickness
Solution Approach 2:
The patent uses a composite resist system combining a base polymer with a polymer-bound acid generator, where the acid generator is covalently bonded to the polymer chains. This composite structure ensures uniform acid distribution and reduces aggregation, improving pattern uniformity and reducing LWR
2Manufacturing precision
If the acid diffusion distance is reduced to improve LWR, then the line width roughness is reduced, but the sensitivity becomes lower
Solution Approach 1:
The patent optimizes the molecular weight and structure of the polymer-bound acid generator to control acid diffusion distance while maintaining generation efficiency. The specific structural design (fluorinated sulfonic acid, covalent bonding) enables short acid diffusion distance without sacrificing sensitivity
Solution Approach 2:
The patent uses a polymer-bound acid generator that replicates the acid generation function throughout the polymer chains, ensuring uniform acid distribution and maintaining high sensitivity while limiting acid diffusion to very short distances
3Measurement precision
If the amount of acid generator is increased to enhance sensitivity, then the sensitivity is enhanced, but the acid diffusion distance is increased leading to degraded LWR and CDU
Solution Approach 1:
The patent employs a composite system where the acid generator is integrated into the polymer matrix through covalent bonding. This ensures uniform distribution of acid generation sites throughout the resist film, preventing aggregation and ensuring consistent acid diffusion characteristics that improve both sensitivity and CDU
Solution Approach 2:
The patent modifies the acid generator parameters by using fluorinated sulfonic acid groups with specific molecular weight ranges (1000-500,000) to control acid diffusion characteristics while maintaining high sensitivity, thereby improving CDU without sacrificing sensitivity
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 resist composition achieves high sensitivity, improved LWR, and CDU, along with increased resolution and process margin, effectively addressing the tradeoff between sensitivity and LWR, and maintaining these benefits across both positive and negative tone patterns.
Implementation Method 1
a polymer-bound acid generator capable of generating a polymer type sulfonic acid upon exposure
Implementation Method 2
the diffusion of generated acid
Data Source
AI summary
A resist composition contains a polymer-bound acid generator, specifically a polymer comprising recurring units derived from a sulfonium or iodonium salt having a polymerizable unsaturated bond and containing iodine in the linker between the polymerizable unsaturated bond and a fluorosulfonic acid. The resist composition offers a high sensitivity and improved CDU independent of whether it is of positive or negative tone.