Steroid Keto Ester Resist for High Resolution and Low LER
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Solution Overview
Problem
Current chemically amplified positive resist compositions used in micropatterning with excimer laser lithography face challenges in achieving high resolution and minimizing line edge roughness (LER) as feature sizes are reduced, with existing acid-decomposable ester compounds being insufficient in improving LER and sometimes degrading resolution.
Innovation Solution
A chemically amplified positive resist composition incorporating an acid-decomposable keto ester compound with a steroid skeleton, which is insoluble in alkaline developers but becomes soluble under acidic conditions, combined with a base resin, acid generator, organic solvent, quencher, and optional surfactant, to enhance resolution and reduce LER.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing acid-decomposable ester compounds are added to improve LER, then LER is reduced, but resolution is degraded
Solution Approach 1:
The patent modifies the molecular structure of acid-decomposable compounds by introducing a steroid skeleton with specific keto ester groups. This structural parameter change creates a compound that decomposes more selectively and uniformly under acid catalysis, reducing LER while preserving the sharp pattern edges needed for high resolution. The specific ratio of keto to ester groups and the steroid backbone rigidity control the decomposition behavior to achieve both low LER and high resolution simultaneously.
Solution Approach 2:
The patent creates a composite resist system combining the steroid-based keto ester compound with specific base resins (polyhydroxystyrene derivatives) and acid generators. This composite formulation synergistically improves LER through the steroid compound's uniform decomposition while the base resin maintains pattern fidelity for high resolution. The composite approach allows each component to contribute its strengths without the trade-off present in single-component systems.
2Productivity
If feature size is reduced to achieve higher integration density, then integration density increases, but LER and resolution requirements become more stringent
Solution Approach 1:
The patent adjusts the chemical parameters of the resist composition by incorporating steroid-based keto ester compounds with controlled molecular weights and functional group ratios. These parameter changes enable the resist to maintain smooth line edges (low LER) even when pattern dimensions are reduced to sub-100nm scales, supporting higher integration density without sacrificing manufacturing precision.
Solution Approach 2:
The acid-decomposable steroid compounds perform preliminary action by pre-positioning decomposition sites within the resist matrix before exposure. During development, these pre-positioned sites decompose uniformly, creating clean pattern edges that prevent LER formation even in ultra-fine features, thereby enabling high integration density with maintained precision.
3Use of energy by moving object
If sensitivity is increased to reduce exposure dose, then exposure dose decreases, but pattern fidelity may be compromised
Solution Approach 1:
The patent modifies the chemical sensitivity parameters of the resist by incorporating steroid-based keto ester compounds that exhibit enhanced acid generation efficiency. This allows the resist to achieve adequate solubility contrast and pattern formation at lower exposure doses while the controlled decomposition kinetics maintain sharp pattern edges and high fidelity, avoiding the trade-off between sensitivity and pattern quality.
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 composition achieves improved resolution and minimized LER, making it suitable for micropatterning in deep-UV, EUV, and electron beam lithography, and can be applied to both conventional and immersion lithography processes.
Implementation Method 1
an acid-decomposable keto ester compound of steroid skeleton which is insoluble in alkaline developer, but turns soluble in alkaline developer under the action of acid
Implementation Method 2
an acid generator as essential components
Data Source
AI summary
A chemically amplified positive resist composition comprises an acid-decomposable keto ester compound of steroid skeleton which is insoluble in alkaline developer, but turns soluble in alkaline developer under the action of acid. The composition is exposed to EB, deep-UV or EUV and developed to form a pattern with a high resolution and improved LER.