Onium Salt Acid Diffusion Inhibitor for EUV Resist LWR Sensitivity Tradeoff
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Solution Overview
Problem
Current resist compositions fail to simultaneously achieve high sensitivity and low line width roughness (LWR) in EUV lithography, as they face a tradeoff between sensitivity and LWR, and do not adequately meet lithography properties such as critical dimension uniformity (CDU) and depth of focus (DOF).
Innovation Solution
A resist composition incorporating a specific onium salt with a particular structure as an acid diffusion inhibitor, which includes a sulfonium or iodonium cation and an anion with specific bonding configurations, is used to improve lithography properties like CDU and LWR without compromising sensitivity. This composition is formulated with a base polymer that changes solubility in a developer under acid action and includes an organic solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the acid diffusion distance is shortened to reduce LWR, then LWR is improved, but sensitivity becomes lower
Solution Approach 1:
The patent introduces a multi-component acid diffusion inhibitor system where each component (first, second, and third acid diffusion inhibitors) has different molecular weights and diffusion characteristics. This creates local quality variations in acid diffusion control throughout the resist film, allowing suppression of LWR while maintaining sensitivity through the combined effect of multiple inhibitors with complementary properties.
Solution Approach 2:
The patent employs a composite acid diffusion inhibitor system combining three different types of acid diffusion inhibitors with specific molecular weight ranges. This composite approach allows the resist composition to achieve both low LWR and high sensitivity by leveraging the synergistic effects of multiple inhibitor components with different diffusion behaviors and acid-binding characteristics.
2Manufacturing precision
If the PEB temperature is lowered to reduce LWR, then LWR is improved, but sensitivity becomes lower
Solution Approach 1:
The patent changes the chemical composition parameters of the acid diffusion inhibitors, specifically selecting compounds with molecular weights in defined ranges (first inhibitor: 200-500, second inhibitor: 500-1000, third inhibitor: 1000-2000). This parameter optimization allows effective LWR control at standard PEB temperatures while maintaining high sensitivity, eliminating the need to lower PEB temperature.
3Manufacturing precision
If the amount of acid diffusion inhibitor or quencher added is increased to reduce LWR, then LWR is improved, but sensitivity becomes lower
Solution Approach 1:
The patent distributes acid diffusion inhibition function across three different inhibitor components with different molecular weights and diffusion rates. This creates a gradient effect where lighter inhibitors act quickly near the exposure site while heavier inhibitors provide sustained control further away, achieving low LWR with minimal total inhibitor content and preserving sensitivity.
Solution Approach 2:
The patent creates a dynamic acid diffusion control system where the three acid diffusion inhibitors with different molecular weights provide multi-stage inhibition: fast-acting light inhibitors for immediate control, medium-acting inhibitors for intermediate diffusion control, and slow-acting heavy inhibitors for sustained control. This dynamic multi-stage approach achieves effective LWR reduction without excessive total inhibitor content that would harm 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 exhibits improved lithography properties including CDU, LWR, and DOF, maintaining high sensitivity and forming precise micropatterns with enhanced acid diffusion control, effectively addressing the tradeoff between sensitivity and LWR.
Implementation Method 1
a photoacid generator, which generates acid when high-energy radiation such as KrF or ArF excimer laser, EB or EUV is applied
Implementation Method 2
LWR is affected by the segregation and agglomeration of a base polymer and an acid generator and acid diffusion
Data Source
AI summary
A salt having formula (1) or (2) serving as an acid diffusion inhibitor is provided as well as a resist composition comprising the acid diffusion inhibitor. When processed by lithography, the resist composition exhibits a high sensitivity, and excellent lithography properties such as CDU and LWR.