Chemically Amplified Positive Resist Composition for Low-LER Patterns
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Solution Overview
Problem
Current chemically amplified resist compositions face challenges in controlling acid diffusion, leading to issues such as line edge roughness (LER), dimensional uniformity (CDU) loss, and pattern collapse during development, especially in the formation of small feature sizes required for advanced lithography processes.
Innovation Solution
A chemically amplified positive resist composition utilizing a polymer with repeat units derived from an onium salt containing an aromatic sulfonic acid anion and phenolic hydroxy groups, which enhances solvent solubility and improves lithographic performance, including resolution, LER, pattern profile, and etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional acid generators are used in chemically amplified resist compositions, then the resist can achieve basic patterning functionality, but acid diffusion occurs leading to line edge roughness and dimensional uniformity loss
Solution Approach 1:
The patent introduces a quencher component as an intermediary substance that interacts with the acid generated during exposure. The quencher captures and neutralizes the diffusing acid before it can cause significant lateral spread, thereby reducing line edge roughness and maintaining dimensional uniformity. This mediator approach allows the resist system to function with conventional acid generators while mitigating their harmful diffusion effects.
Solution Approach 2:
The patent modifies the chemical parameters of the resist composition by incorporating specific base polymers with controlled glass transition temperatures and acid diffusion characteristics. By adjusting the glass transition temperature through polymer selection and by controlling the concentration and type of base polymer, the patent optimizes the matrix properties to limit acid diffusion while maintaining adequate solubility and patterning performance.
2Productivity
If the resist film is made highly sensitive to reduce writing time, then throughput improves, but temporal stability of the exposed region deteriorates
Solution Approach 1:
The patent applies a protective film over the resist pattern after development as a preliminary stabilization step. This protective coating prevents further chemical changes, acid diffusion, or environmental effects that could alter the exposed region characteristics over time. By stabilizing the pattern immediately after formation, the patent maintains both high sensitivity for fast processing and temporal stability for subsequent handling.
3Manufacturing precision
If the resist composition is optimized for high resolution, then pattern definition improves, but pattern collapse during development increases
Solution Approach 1:
The patent employs a composite resist composition consisting of multiple carefully selected components: base polymer, acid generator, quencher, and solvent. This composite formulation balances the competing requirements by combining materials with complementary properties - the base polymer provides structural integrity to prevent collapse, while the acid generator and quencher system ensures high resolution through controlled acid diffusion. The synergistic interaction of these composite components resolves the contradiction between pattern definition and collapse resistance.
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 resolution with small LER, excellent etch resistance, and reduced pattern collapse, suitable for fine pattern formation in EB and EUV lithography.
Implementation Method 1
a base polymer comprising a polymer containing repeat units having the formula (A1) and repeat units having the formula (A2), the polymer being adapted to increase its solubility in an aqueous alkaline under the action of an acid
Implementation Method 2
The major cause of such a change with time is diffusion of an acid generated upon exposure
Data Source
AI summary
A chemically amplified positive resist composition comprises a base polymer comprising a polymer containing repeat units having the formula (A1) and repeat units having the formula (A2), the polymer being adapted to increase its solubility in an aqueous alkaline under the action of an acid.