Non-ionic PAGs with Aryl Ketone Groups for EUV Lithography
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Solution Overview
Problem
Current EUV lithography resists face challenges with image blur due to gradient-driven acid diffusion, and existing non-ionic photo-acid generators (PAGs) with aryl ketone protecting groups are unstable and highly diffusing, limiting their thermal and hydrolytic stability.
Innovation Solution
Development of non-ionic PAG compounds with aryl ketone groups that release strong sulfonic acids with low diffusion rates, suitable for use in EUV lithography, which are thermally stable up to at least 130°C and form stable resist patterns with reduced volatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If non-ionic PAGs with aryl ketone protecting groups are used, then higher solubility in casting solvents and homogeneous distribution in the resist film are achieved, but thermal and hydrolytic stability deteriorate and acid diffusion increases
Solution Approach 1:
The patent modifies the chemical structure of non-ionic PAGs by changing parameters such as introducing fluorinated substituents and adjusting the aryl ketone protecting group configurations. These structural parameter changes enhance thermal and hydrolytic stability while controlling acid diffusion characteristics, resolving the contradiction between stability and diffusion control.
Solution Approach 2:
The patent employs composite molecular structures combining fluorinated sulfonic acid moieties with aryl ketone protecting groups. This composite approach creates a synergistic effect where the fluorinated portion provides stability and the aryl ketone portion controls diffusion, simultaneously achieving both improved stability and reduced acid diffusion.
2Manufacturing precision
If existing non-ionic PAGs with aryl ketone protecting groups are used, then homogeneous distribution in the resist film is achieved, but pattern fidelity deteriorates due to high acid diffusion
Solution Approach 1:
The patent introduces local structural features within the PAG molecule, such as specific fluorinated substituents and sterically hindered aryl ketone groups, that create localized regions of high acid generation capability coupled with low diffusion. This local quality differentiation ensures acid is generated where needed but does not diffuse away, improving pattern fidelity.
Solution Approach 2:
The aryl ketone protecting group acts as an intermediary between the sulfonic acid source and the resist matrix. It mediates the release of acid in a controlled manner, preventing direct diffusion of the acid through the resist film while still enabling the necessary chemical amplification, thus improving pattern fidelity.
3Power
If volatile sulfonic acids are produced by aryl ketone PAGs, then acid generation capability is improved, but thermal stability deteriorates and volatility increases
Solution Approach 1:
The patent changes the thermal parameters of the PAG system by introducing fluorinated substituents and cyclic aryl ketone structures. These modifications raise the thermal decomposition temperature and reduce volatility while maintaining strong acid generation capability upon photolysis, resolving the contradiction between acid generation power and thermal stability.
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 new PAG compounds enhance thermal and hydrolytic stability, reduce acid diffusion, and improve pattern fidelity in EUV lithography, enabling the formation of high-resolution patterns with lower defects associated with out-of-band radiation exposures.
Implementation Method 1
the PAG present in the resist composition produces a strong acid, which then catalyzes the removal of the acid-labile groups upon heating exposed resist layer in a post-exposure bake (PEB)
Implementation Method 2
One phenomenon that limits the resolution potential of the resists developed for 248 nm, 193 nm and E-beam applications is referred to as 'image blur'... gradient-driven acid diffusion
Implementation Method 3
a base quencher; wherein the resin, the base quencher, and the PAG compound are in contact with the solvent
Data Source
AI summary
Non-ionic photo-acid generating (PAG) compounds were prepared that contain an aryl ketone group. The disclosed non-polymeric PAGs release a strong sulfonic acid when exposed to high energy radiation such as deep UV or extreme UV light. The photo-generated sulfonic acid has a low diffusion rate in an exposed resist layer subjected to a post-exposure bake (PEB) at 100° C. to 150° C., resulting in formation of good line patterns after development. At higher temperatures, the PAGs undergo a thermal reaction to form a sulfonic acid.