Chemically-Amplified Resist Composition for High-Resolution Lithography
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Solution Overview
Problem
In electron beam lithography, achieving high sensitivity, temporal stability, and high resolution pattern formation with minimal line width variance is challenging, especially for photo mask blanks with chrome or nitrogen-containing silicon surfaces, where traditional resist compositions fail to maintain pattern profile integrity over time and substrate variations.
Innovation Solution
A chemically-amplified positive resist composition incorporating a base polymer with acetal-protected monomer units, a sulfonium salt generating 1-adamantane sulfonic acid, and a basic component to enhance solubility and resolution, ensuring high sensitivity, temporal stability, and substrate-independent pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a chemically-amplified resist is used for fine pattern formation, then high sensitivity is achieved, but temporal stability deteriorates due to longer drawing times
Solution Approach 1:
The patent changes the chemical parameters of the resist system by introducing a dual-acid catalyst mechanism with different acid strengths (super acid and strong acid) and different release timings. The super acid provides initial catalytic action for high sensitivity, while the strong acid maintains stability during prolonged exposure. This parameter differentiation resolves the contradiction between sensitivity and temporal stability.
Solution Approach 2:
The patent introduces a base polymer as an intermediary component that modulates acid catalyst activity. The base polymer contains basic groups that temporarily bind and then release acid catalysts in a controlled manner, creating a time-dependent release mechanism. This intermediary function allows the system to achieve both high initial sensitivity and sustained temporal stability during long exposure times.
2Manufacturing precision
If sequential electron beam exposure is used for fine area processing, then pattern precision is improved, but productivity deteriorates due to longer operation time
Solution Approach 1:
The patent changes the sensitivity parameter of the resist by optimizing the acid catalyst system and polymer composition. The enhanced sensitivity allows the resist to respond more efficiently to the sequential electron beam exposure, reducing the required exposure time and dose. This parameter optimization enables high precision patterning while improving throughput by reducing the total processing time.
3Shape
If super acid catalysts are used to achieve rectangular profile, then pattern shape is improved, but manufacturing complexity increases
Solution Approach 1:
The patent creates a composite acid catalyst system combining super acid and strong acid components within a single resist formulation. This composite approach integrates multiple functional elements (different acid strengths, different release characteristics) into one manufacturable product. The base polymer acts as a common matrix holding both acid types, simplifying manufacturing while achieving the desired rectangular profile through the synergistic action of the acid components.
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 a high resolution, minimal line width variance, and excellent pattern profile stability even with prolonged exposure times, suitable for fine processing and VLSI manufacturing, effectively addressing the limitations of traditional resist compositions.
Implementation Method 1
a sulfonium salt compound that liberates an 1-adamantane sulfonic acid represented by the above formula (5) by a light-exposure
Data Source
AI summary
There is disclosed a chemically-amplified positive resist composition comprising, as main components, (A) a base polymer, which contains one or more kinds of a monomer unit represented by the following general formula (1) and the like, and is an alkali-insoluble polymer whose hydroxyl group is partly protected by an acetal group while alkali-soluble when deprotected by an acid catalyst, (B) a sulfonium salt containing a sulfonate anion, (C) a basic component, and (D) an organic solvent. In a lithography technology by a photo resist, an extremely high temporal stability is necessary. In addition, it must give a good pattern profile not dependent on a substrate and have a high resolution power. There can be provided a chemically-amplified positive resist composition which can solve these problems simultaneously, a resist patterning process using the same, and a method for producing a photo mask blank.