Chemically Amplified Positive Resist for Controlled Acid Diffusion
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Solution Overview
Problem
Current chemically amplified resist compositions face challenges in achieving high resolution, reduced line-edge roughness (LER), improved rectangularity, and etching resistance, particularly in the processing of photomask blanks and semiconductor substrates, due to uncontrolled acid diffusion and solubility issues in organic solvents.
Innovation Solution
A chemically amplified positive resist composition comprising a base polymer with specific polydispersity and repeat units derived from hydroxystyrene or hydroxynaphthalene, combined with a photoacid generator and organic solvent, which minimizes acid diffusion and enhances solubility, resulting in high-resolution patterns with reduced LER and improved etching resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acid generators are used to increase sensitivity, then exposure sensitivity is improved, but acid diffusion increases causing reduced resolution and increased LER
Solution Approach 1:
The patent introduces a polymer comprising repeat units capable of generating acid upon exposure as an intermediary substance. This polymer acts as a mediator between the exposure process and the final pattern formation, providing controlled acid generation that limits diffusion while maintaining sensitivity. The polymer structure serves as a carrier that releases acid in a controlled manner during post-exposure bake, resolving the contradiction between sensitivity and resolution.
Solution Approach 2:
The patent changes the physical and chemical parameters of the acid generation system by using a polymer with specific repeat units that have controlled acid-generating properties. By adjusting the polymer structure, molecular weight, and composition, the acid diffusion distance is precisely controlled while maintaining high exposure sensitivity. This parameter change allows simultaneous achievement of high resolution and acceptable sensitivity.
2Manufacturing precision
If repeat units capable of generating acid upon exposure are introduced into base polymer, then acid diffusion is controlled and LER is reduced, but solubility in organic solvent deteriorates
Solution Approach 1:
The patent applies local quality by incorporating acid-generating repeat units at specific positions within the polymer structure rather than uniformly throughout. The polymer comprises a base structure with specific repeat units introduced at controlled frequencies and positions, allowing acid diffusion control in critical regions while maintaining overall polymer solubility through the base structure's properties.
Solution Approach 2:
The patent creates a composite polymer structure combining base polymer units with acid-generating repeat units. This composite material approach allows the base polymer to provide solubility and processability while the incorporated repeat units provide controlled acid generation. The synergistic combination resolves the contradiction between pattern uniformity and solubility.
3Productivity
If high-sensitivity resist composition is used for EB lithography, then throughput is improved, but pattern profile rectangularity and etching resistance deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-configuring the polymer structure with specific repeat units that will generate acid upon exposure. The polymer is designed in advance with controlled molecular weight, dispersity, and repeat unit distribution to ensure that during post-exposure bake, acid is generated and diffused in a controlled manner that produces rectangular profiles. This preliminary structural design enables both high sensitivity and good profile retention.
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 enables the formation of resist patterns with high resolution, reduced LER, and enhanced rectangularity, while minimizing residue defects and maintaining etch resistance, suitable for advanced lithography processes such as EUV and EB lithography.
Implementation Method 1
a photoacid generator capable of generating a specific aromatic sulfonic acid
Implementation Method 2
adapted to increase its solubility in alkaline aqueous solution under the action of acid
Data Source
AI summary
A chemically amplified positive resist composition is provided comprising a polymer having a dispersity of 1.01-1.19 and comprising repeat units derived from hydroxystyrene or hydroxynaphthalene, and repeat units derived from hydroxystyrene or hydroxynaphthalene having a hydroxy group protected with an acid labile group, a photoacid generator, and an organic solvent. From a resist film of the composition, a resist pattern of small feature size having satisfactory isolated-space resolution, reduced LER, good rectangularity, etch resistance and collapse resistance is formed.