Resist Composition With Polymer-Bound Acid Control for Fine Patterning
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Solution Overview
Problem
Existing resist compositions face challenges in achieving high sensitivity, resolution, and reduced line width roughness (LWR) while minimizing acid diffusion, which affects the formation of fine patterns in microelectronic devices.
Innovation Solution
A resist composition comprising a base polymer with repeat units of carboxylic acid anions and sulfonic acid anions bonded to the backbone, along with specific functional groups and organic cations, is used to control acid diffusion and enhance dissolution contrast, resulting in improved critical dimension uniformity (CDU) and reduced LWR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is suppressed to improve resolution, then manufacturing precision is improved, but sensitivity deteriorates
Solution Approach 1:
The patent applies local quality by incorporating a polymer-bound acid generator directly into the polymer backbone at specific locations. This creates localized acid generation sites that limit acid diffusion to immediate surroundings, thereby improving resolution while maintaining sufficient acid concentration for high sensitivity. The acid generator is not uniformly distributed but strategically positioned within the polymer structure.
Solution Approach 2:
The patent uses composite materials by combining the polymer backbone with integrated acid generator units (sulfonium or iodonium salts with polymerizable unsaturated bonds). This composite structure allows the resist to possess both the solubility and mechanical properties of the polymer and the acid-generating capability of the onium salt, achieving both high resolution and high sensitivity simultaneously.
2Manufacturing precision
If post-exposure bake temperature and time are reduced to minimize acid diffusion, then manufacturing precision is improved, but sensitivity and contrast deteriorate
Solution Approach 1:
The patent extracts the acid generation function from a separate additive and integrates it directly into the polymer backbone. This eliminates the need for high-temperature PEB to activate separate acid generators, as the polymer-bound acid generators are structurally predisposed to decompose at lower temperatures, thereby maintaining sensitivity and contrast while reducing acid diffusion.
Solution Approach 2:
The patent changes the thermal decomposition parameters of the acid generator by using polymer-bound sulfonium or iodonium salts instead of conventional small-molecule acid generators. This structural modification lowers the decomposition temperature, enabling effective acid generation at reduced PEB temperatures and times, thus resolving the contradiction between acid diffusion control and sensitivity maintenance.
3Productivity
If feature size is reduced to achieve higher integration density, then productivity is improved, but image blur due to acid diffusion worsens manufacturing precision
Solution Approach 1:
The patent applies local quality by creating highly localized acid generation zones through polymer-bound acid generators. Each acid generator unit is fixed at a specific position on the polymer backbone, ensuring that acid diffusion is confined to a very small radius. This localized acid generation enables the formation of finer patterns with reduced LWR, supporting higher integration density while maintaining pattern resolution.
4Productivity
If conventional acid generators are used to enhance sensitivity, then productivity is improved, but acid diffusion increases and worsens manufacturing precision
Solution Approach 1:
The patent uses composite materials by creating a unified polymer-acid generator structure where the acid generator is covalently bonded to the polymer backbone. This composite design ensures that the acid generator remains fixed in position during the resist process, preventing the migration and excessive diffusion that plagues conventional small-molecule acid generators, while still providing high sensitivity through efficient acid generation.
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, resolution, and forms patterns with satisfactory profiles, reducing LWR and improving CDU, making it suitable for small-size pattern formation in VLSIs and photomasks.
Implementation Method 1
a sulfonic acid anion bonded to the backbone and a sulfonium cation... capable of generating a bulky acid
Implementation Method 2
image blurs due to acid diffusion become a problem... control of acid diffusion is also important
Data Source
AI summary
A resist composition comprising a base polymer comprising repeat units consisting of a carboxylic acid anion having iodine and a specific functional group, bonded to the backbone and an organic cation and repeat units consisting of a sulfonic acid anion bonded to the backbone and a sulfonium cation has a high sensitivity and a high contrast of alkaline dissolution rate before and after exposure. A pattern of satisfactory profile with reduced LWR and improved CDU is formed therefrom.