Resist Composition Quencher for Acid Diffusion and LWR Control
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Solution Overview
Problem
Existing resist compositions face challenges in controlling acid diffusion, leading to image blurs and reduced sensitivity, which are critical for achieving high resolution and uniformity in microelectronic device manufacturing, particularly at the 5-nm node and beyond.
Innovation Solution
Incorporation of a sulfonium salt of a carboxylic acid with a specific nitrobenzene ring as a quencher in the resist composition, which suppresses acid diffusion and enhances line width roughness (LWR) and critical dimension uniformity (CDU) by controlling acid diffusion and reducing swell in alkaline developers.
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 and contrast are drastically reduced
Solution Approach 1:
The invention changes the chemical nature of the acid from small molecular weight acids (which diffuse easily) to bulky acids with molecular weights of 100 or more (which diffuse minimally). This parameter change in acid size and structure allows suppression of acid diffusion while maintaining the chemical amplification effect, thereby resolving the contradiction between resolution and sensitivity/contrast
Solution Approach 2:
The invention uses a composite approach by combining a specific base polymer with a polymer-bound acid generator that generates bulky acids. This composite system enables simultaneous achievement of high resolution (through suppressed acid diffusion) and high sensitivity/contrast (through maintained chemical amplification), resolving the technical contradiction
2Manufacturing precision
If acid diffusion is suppressed by using bulky acids, then resolution is improved, but the tradeoff relationship among sensitivity, resolution, and edge roughness (LWR) becomes problematic
Solution Approach 1:
By changing the fundamental parameter of acid size to bulky acids (MW≥100), the invention breaks the traditional tradeoff relationship. The bulky acid structure inherently provides suppressed diffusion without sacrificing sensitivity, as the polymer-bound generator maintains chemical amplification while the bulky acid structure prevents excessive diffusion that would cause LWR issues
Solution Approach 2:
The polymer-bound acid generator acts as an intermediary that decouples the relationship between acid generation and acid diffusion. The polymer backbone holds the acid generator in place, and upon exposure, releases bulky acids that diffuse minimally. This intermediary structure allows independent optimization of sensitivity (through chemical amplification) and resolution (through suppressed diffusion)
3Reliability
If conventional quenchers are used, then sensitivity is maintained, but acid diffusion control and LWR reduction are insufficient
Solution Approach 1:
The invention changes the quencher from conventional small molecular weight compounds to polymer-bound quenchers with molecular weights of 100 or more. This parameter change in quencher size provides enhanced acid diffusion control and improved LWR/CDU while maintaining sensitivity through the polymer-bound structure that ensures uniform distribution and controlled quenching
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 sulfonium salt effectively improves sensitivity, reduces LWR, and enhances CDU, providing improved resolution and process margins for both positive and negative tone patterns.
Implementation Method 1
When a sulfonium or iodonium salt capable of generating strong acid is mixed with a sulfonium or iodonium salt capable of generating weak acid, the sulfonium or iodonium salt capable of generating weak acid undergoes ion exchange with the strong acid. Through the ion exchange, the strong acid once generated upon light exposure is converted back to the sulfonium or iodonium salt.
Implementation Method 2
Like photoacid generators, the quenchers of sulfonium or iodonium salt type are photo-decomposable. This means that the amount of quencher in the exposed region is reduced.
Data Source
AI summary
A resist composition comprising a sulfonium salt of a carboxylic acid having a nitro-substituted benzene ring is provided. The carboxylic acid is free of iodine and bromine, and when the benzene ring is fluorinated, the number of fluorine atoms is up to 3. The resist composition offers a high sensitivity, reduced LWR and improved CDU independent of whether it is of positive or negative tone.