Resist Composition for Acid Diffusion Control in 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 iodized carboxylic acid anions and iodized sulfonic acid anions bonded to the backbone, along with additional units to enhance dissolution contrast, is used to control acid diffusion and improve pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acid diffusion is suppressed by reducing temperature and/or time of post-exposure bake, then resolution is improved, but sensitivity is drastically reduced
Solution Approach 1:
The patent changes the chemical parameters of the acid generator by using a polymer-bound acid generator with specific repeat units (Formula 1 and Formula 2) that have controlled acid diffusion characteristics. The acid diffusion coefficient is specifically controlled to be 10^-7 to 10^-9 cm²/s, which allows maintaining sensitivity while improving resolution by suppressing excessive acid diffusion.
Solution Approach 2:
The patent uses a composite polymer structure containing both Formula 1 repeat units (with acid diffusion control) and Formula 2 repeat units (with dissolution contrast enhancement). This composite approach allows simultaneous achievement of high sensitivity, high resolution, and low LWR by combining the functions of different repeat units within the same polymer chain.
2Manufacturing precision
If acid diffusion distance is reduced to improve resolution, then manufacturing precision is improved, but sensitivity is reduced
Solution Approach 1:
The patent specifically controls the acid diffusion coefficient parameter to be within 10^-7 to 10^-9 cm²/s by selecting appropriate polymer-bound acid generators. This parameter optimization allows the acid to diffuse just enough to provide sufficient sensitivity while limiting excessive diffusion that would degrade resolution.
3Manufacturing precision
If line width roughness is reduced to improve pattern quality, then manufacturing precision is improved, but this requires precise control of acid diffusion which complicates the process
Solution Approach 1:
The patent employs a composite polymer with Formula 1 repeat units that control acid diffusion and Formula 2 repeat units that enhance dissolution contrast. This material-level solution reduces LWR through intrinsic polymer design rather than complex process control, thereby reducing process complexity while maintaining high manufacturing precision.
4Productivity
If dissolution contrast is improved to enhance sensitivity, then productivity is improved, but acid diffusion control becomes more critical which may worsen resolution
Solution Approach 1:
The patent integrates both acid diffusion control (Formula 1) and dissolution contrast enhancement (Formula 2) within the same polymer chain. The Formula 2 repeat units provide the necessary dissolution contrast for high sensitivity, while the Formula 1 repeat units simultaneously control acid diffusion to maintain high resolution, eliminating the trade-off between these parameters.
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 high sensitivity, resolution, and reduced LWR, forming patterns with improved critical dimension uniformity (CDU) suitable for small-size pattern formation in VLSIs and photomasks.
Implementation Method 1
image blurs due to acid diffusion become a problem... control of acid diffusion is also important... To restrain acid diffusion, Patent Documents 3 to 5 disclose resist compositions comprising a base polymer comprising repeat units derived from a polymerizable group-containing sulfonium salt of a weak acid
Implementation Method 2
The addition of an acid generator capable of generating a bulky acid is an effective means for suppressing acid diffusion. It was then proposed to incorporate repeat units derived from an onium salt having a polymerizable unsaturated bond in a polymer. Since this polymer functions as an acid generator, it is referred to as polymer-bound acid generator.
Data Source
AI summary
A resist composition comprising a base polymer comprising repeat units consisting of an iodized carboxylic acid anion bonded to the backbone and an organic cation and repeat units consisting of an iodized sulfonic acid anion bonded to the backbone and a sulfonium cation has a high sensitivity and resolution. A pattern of satisfactory profile with reduced LWR and improved CDU is formed therefrom.