Bis-Onium Resist Composition for EUV Sensitivity and LWR Control
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Solution Overview
Problem
Existing resist materials face a tradeoff between sensitivity and line width roughness (LWR) or critical dimension uniformity (CDU), with EUV lithography requiring high sensitivity, low LWR, and improved CDU without acid diffusion blurring.
Innovation Solution
A resist composition using a bis-onium salt with a divalent anion structure, combining an iodized phenoxide and fluorosulfonic acid anion bonded to an aromatic ring, acts as both an acid generator and quencher, directly excited by EUV radiation, minimizing acid diffusion and enhancing sensitivity, LWR, and CDU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PEB temperature is lowered to reduce acid diffusion distance, then LWR or CDU is improved, but sensitivity becomes lower
Solution Approach 1:
The patent merges the acid generator and quencher into a single bis-onium salt molecule, where the iodized phenoxide anion structure serves as the quencher and the fluorosulfonic acid anion structure serves as the acid generator. This integration ensures that the quencher is always located at a fixed distance from the acid generation site, providing localized acid diffusion control without requiring low PEB temperature, thus maintaining both low LWR and high sensitivity.
Solution Approach 2:
The invention uses a composite molecular structure combining two functional anions (iodized phenoxide and fluorosulfonic acid) into a single bis-onium salt. This composite structure leverages the high EUV absorption of iodine and the strong acid generation capability of fluorosulfonic acid, achieving both high sensitivity and controlled acid diffusion simultaneously.
2Manufacturing precision
If the amount of quencher added is increased to improve LWR or CDU, then sensitivity becomes lower
Solution Approach 1:
The patent combines the acid generator and quencher into a single molecular entity (bis-onium salt), eliminating the need to add separate quencher components. The quencher function is built-in at the molecular level, ensuring optimal quencher-to-acid-generator ratio and localized action, thereby improving LWR without sacrificing sensitivity.
3Productivity
If iodine or bromine is added to enhance physical contrast and sensitivity, then LWR is degraded due to photon absorption variation
Solution Approach 1:
The invention uses a composite anion structure where iodized phenoxide provides high EUV absorption for sensitivity enhancement, while fluorosulfonic acid provides controlled acid generation. The fixed molecular geometry ensures consistent photon absorption and localized acid diffusion, achieving both high sensitivity and low LWR.
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 bis-onium salt composition achieves high sensitivity, reduced LWR, and improved CDU, maintaining resolution and process margin in both positive and negative tone patterns.
Implementation Method 1
the acid generator is directly excited upon exposure to radiation
Implementation Method 2
a fluorosulfonic acid anion structure bonded to the aromatic ring of the phenoxide anion structure, and onium cations. The bis-onium salt is directly excited upon exposure to radiation
Data Source
AI summary
A resist composition is provided comprising a bis-onium salt consisting of a divalent anion having an iodized phenoxide anion structure and a fluorosulfonic acid anion structure bonded to the aromatic ring of the phenoxide anion structure, and onium cations. It exhibits a high sensitivity and forms a pattern with reduced LWR or improved CDU independent of whether it is of positive or negative type.