Hypervalent Iodine Resist Composition for High-Resolution EUV Patterning
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Solution Overview
Problem
Existing resist compositions face challenges in achieving high sensitivity and resolution for fine patterns in photolithography, particularly in EUV lithography, due to issues such as acid diffusion, low solubility, and the influence of shot noise, leading to increased CDU and LWR, and require additional steps for pattern reversal.
Innovation Solution
A resist composition comprising a hypervalent iodine compound with a predetermined carboxylate ligand and a carboxylic acid, which forms a resist film that exhibits high sensitivity and resolution through a non-chemically amplified mechanism, allowing for precise micropatterning without acid diffusion and shot noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemically amplified resist composition is used to enhance sensitivity and contrast through acid diffusion, then sensitivity and contrast are improved, but acid diffusion causes image blur and reduces resolution for fine patterns
Solution Approach 1:
The patent changes the fundamental mechanism from chemically amplified (acid diffusion-based) to direct photo-decomposition. By using a positive resist composition where the polymer itself decomposes upon exposure without requiring acid diffusion, the patent eliminates image blur while maintaining high sensitivity. The key parameter change is replacing the chemical amplification mechanism with direct photodecomposition of the polymer chains.
Solution Approach 2:
The patent extracts and removes the acid diffusion mechanism from the resist system. By using a positive resist composition that relies on direct scission of polymer chains upon exposure rather than acid-catalyzed decomposition, the harmful acid diffusion step is completely eliminated, thereby preventing image blur while preserving sensitivity through direct photochemical bond breaking.
2Manufacturing precision
If non-chemically amplified resist composition like PMMA is used to avoid acid diffusion, then resolution is improved, but sensitivity is insufficient
Solution Approach 1:
The patent employs a composite resist system combining a positive-type polymer (PMMA or GPMMA) with a negative-type polymer containing carboxyl groups. This composite approach allows the positive polymer to provide high resolution through direct scission while the carboxyl-containing polymer enhances sensitivity through acid generation and catalytic effects, achieving both high resolution and high sensitivity simultaneously.
Solution Approach 2:
The carboxyl-containing polymer serves multiple functions: it acts as a sensitivity enhancer through acid generation, provides etch resistance, and contributes to pattern formation. This multi-functional component allows the resist system to achieve high sensitivity without compromising the resolution benefits of the positive resist mechanism.
3Manufacturing precision
If negative resist materials like HSQ are used to achieve high resolution through crosslinking, then edge roughness is reduced, but solubility control becomes difficult and additional reversal steps are required
Solution Approach 1:
The patent inverts the conventional negative resist approach. Instead of using a material that becomes insoluble through crosslinking (requiring reversal), the patent uses a positive resist mechanism where exposed regions become soluble and are removed by developer. This inversion eliminates the need for additional reversal steps while maintaining high resolution and low edge roughness characteristics.
4Manufacturing precision
If EUV lithography is used to achieve smaller pattern features, then resolution is improved, but shot noise increases and causes CDU and LWR degradation
Solution Approach 1:
The patent changes the resist mechanism to direct photodecomposition without chemical amplification, which reduces sensitivity to shot noise. By eliminating the acid diffusion process that amplifies stochastic effects, the patent achieves better CDU and LWR control at EUV node while maintaining the ability to form sub-20nm features.
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 achieves high sensitivity and resolution, reducing LWR and eliminating the need for pattern reversal steps, while being soluble in organic solvents for positive tone or alkali aqueous solutions for negative tone patterns, thus enhancing the precision and efficiency of micropatterning.
Implementation Method 1
a hypervalent iodine compound having a predetermined carboxylate ligand and a carboxylic acid, which forms a resist film that exhibits high sensitivity and resolution through a non-chemically amplified mechanism
Implementation Method 2
Hydrogensilsesquioxane (HSQ) is a negative resist material which turns insoluble in alkaline developer through crosslinking by condensation reaction of silanol generated upon EUV exposure
Data Source
AI summary
A resist composition is provided that comprises a hypervalent iodine compound having the formula (1), a carboxylic acid, and a solvent. The resist composition exhibits a high sensitivity and resolution when processed by photolithography using high-energy radiation, typically EB and EUV lithography, and a pattern forming process using the resist composition.