Polymer-Bound Onium Salt Monomers for EUV LWR Control
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Solution Overview
Problem
Current chemically amplified resist compositions face challenges in achieving high sensitivity, reduced line width roughness (LWR), and improved critical dimension uniformity (CDU) while maintaining etch resistance and solvent solubility, particularly in the context of EUV lithography and the miniaturization of microelectronic devices.
Innovation Solution
A polymer comprising repeat units derived from an onium salt monomer with a sulfonium or iodonium salt containing an aromatic sulfonic acid anion and an iodized aromatic ring structure is used, which acts as a polymer-bound photoacid generator, enhancing solvent solubility, sensitivity, and lithography properties, including LWR and CDU, and providing etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the acid diffusion distance is reduced to decrease LWR, then sensitivity becomes lower
Solution Approach 1:
The acid generator is segmented into multiple functional units: a polymerizable group for chain formation, an onium salt moiety for acid generation, and an iodine-containing aromatic ring for secondary electron generation. This segmentation allows each unit to perform its specific function optimally while working together to resolve the sensitivity-LWR contradiction
Solution Approach 2:
The invention creates a composite acid generator by combining the polymerizable group, onium salt, and iodine-containing aromatic ring into a single molecular structure. This composite structure enables simultaneous achievement of short acid diffusion distance (through polymer binding) and high sensitivity (through iodine-mediated secondary electron generation)
2Productivity
If the amount of acid generator is increased to enhance sensitivity, then acid diffusion distance is increased leading to degraded LWR or CDU
Solution Approach 1:
The invention merges the acid generator with the polymer backbone through covalent bonding, creating a polymer-bound acid generator. This merging ensures that the acid generator remains fixed at specific locations along the polymer chain, preventing aggregation and ensuring uniform acid distribution even at high concentrations, thereby maintaining both sensitivity and pattern uniformity
3Volume of moving object
If the resist film thickness is reduced to comply with size reduction, then LWR becomes greater
Solution Approach 1:
The invention introduces local quality variations through the polymer-bound acid generator structure, where the acid generation capability is locally concentrated at specific polymer chain positions. This local concentration effect maintains effective acid generation even in thin films, preventing LWR degradation while enabling reduced film thickness
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 polymer-based resist composition exhibits high sensitivity, high contrast, and improved LWR and CDU, along with resistance to pattern collapse and etch resistance, suitable for small-size pattern formation.
Implementation Method 1
Since iodine atoms are highly absorptive to EUV of wavelength 13.5 nm, they generate secondary electrons upon light exposure. This effect is noteworthy in the EUV lithography.
Implementation Method 2
a polymer-bound photoacid generator, enhancing solvent solubility, sensitivity, and lithography properties
Data Source
AI summary
A sulfonium or iodonium salt monomer containing an aromatic sulfonic acid anion containing a polymerizable group of a styrene or vinylnaphthalene structure and an iodized aromatic ring structure is a useful acid generator. A resist composition comprising a polymer comprising repeat units derived from the monomer exhibits a high solvent solubility, high sensitivity and high contrast and forms a small-size pattern with satisfactory lithography properties such as EL, LWR, CDU and DOF.