Photoacid Generator Segmentation for Lithography Roughness
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Solution Overview
Problem
Current photoresist compositions for high-resolution lithography lack controlled solubility in both aqueous and non-aqueous solvents, leading to issues with line edge roughness, linewidth roughness, and pattern profile, while also requiring improved process control and diffusion properties.
Innovation Solution
A novel photoacid generator compound with a sulfonium cation and fluorinated groups, spatially segregated from aromatic rings through heteroatom-containing connecting groups, providing high solubility in both alkaline and organic solvents, enabling uniform distribution and improved resolution in photoresists.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoacid generators are used, then photoresist composition is simpler, but solubility control in both aqueous and non-aqueous solvents is insufficient leading to line edge roughness and linewidth roughness
Solution Approach 1:
The photoacid generator molecule is segmented into distinct functional regions: a cationic portion containing fluorinated groups spatially segregated from aromatic rings through heteroatom-containing connecting groups, and an anionic portion. This segmentation enables independent optimization of solubility properties in both aqueous and organic solvents, resolving the roughness issue without requiring overly complex molecular structures.
Solution Approach 2:
Different regions of the photoacid generator molecule are assigned specific local properties: the fluorinated cationic portion provides solubility in organic solvents and low absorbance, while the anionic portion ensures solubility in aqueous developers. This local quality differentiation allows the molecule to simultaneously achieve controlled solubility in both solvent types, eliminating line edge and linewidth roughness.
2Manufacturing precision
If photoacid generators with low absorbance are used, then resolution improves, but solubility characteristics in aqueous and non-aqueous solvents become difficult to control
Solution Approach 1:
The photoacid generator functions as a composite molecular structure combining fluorinated cationic groups with low absorbance properties and anionic groups with controlled solubility. This composite approach allows simultaneous achievement of high resolution (through low absorbance) and controlled solubility in both aqueous and non-aqueous solvents, resolving the adaptability issue.
3Manufacturing precision
If photoresist composition is optimized for high resolution, then smaller critical dimension is achieved, but process control tolerances such as exposure latitude and depth of focus are reduced
Solution Approach 1:
The photoacid generator's solubility parameters are changed through strategic placement of fluorinated groups and heteroatom-containing connecting groups. This parameter optimization enables the photoresist to maintain high resolution (smaller critical dimension) while improving process control tolerances including exposure latitude and depth of focus, as the controlled solubility ensures uniform acid generation and development across varying process conditions.
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 photoacid generator achieves enhanced photoresist resolution, reduced line edge and linewidth roughness, and improved pattern profiles by ensuring high solubility in various developers, thus addressing the limitations of existing PAGs in microlithography.
Implementation Method 1
patternwise exposing the photoresist composition layer to actinic radiation
Implementation Method 2
high solubility in both alkaline and organic solvents, enabling uniform distribution
Implementation Method 3
developing the pattern by treatment with an aqueous alkaline developer to form a positive tone relief image
Data Source
AI summary
A compound having the formula (I):wherein a is an integer of from 1 to 10, and x is an integer of from 1 to 3, X1 comprises a fluoroalcohol, fluorinated ester, or fluorinated anhydride, Y is a single bond, C1-20 alkylene group, O, S, NR, ester, carbonate, sulfonate, sulfone, or sulfonamide, wherein R is H or C1-20 alkyl, and wherein the C1-20 alkylene group is structurally only carbon, or one or more structural carbon atoms in the C1-20 alkylene group is replaced by oxygen, carbonyl, ester, or a combination comprising at least one of the foregoing, Ar is a substituted or unsubstituted, C5 or greater monocyclic, polycyclic, or fused polycyclic cycloalkyl; or a substituted or unsubstituted, C5 or greater monocyclic, polycyclic, or fused polycyclic aryl group, wherein the cycloalkyl or aryl is a carbocycle or comprises a heteroatom comprising O, S, N, F, or a combination comprising at least one of the foregoing, each R1 is independently a substituted C5-40 aryl, substituted C5-40 heteroaryl, C1-40 alkyl, a C3-40 cycloalkyl, wherein when x is 1, the two groups R1 are separate or bonded to each other to form a C4-40 ring structure, and Z− is a carboxylate, sulfate, sulfonate, sulfamate, or the anion of a sulfonimide, wherein when Y is a single bond, Z− is not sulfonate.