Chemically Amplified Negative Resist Composition for Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional chemically amplified negative resist compositions fail to effectively reduce line edge roughness (LER) and minimize substrate poisoning, particularly when forming patterns with feature sizes of 0.1 μm or less, and exhibit undercut issues when used on substrates with chromium oxynitride layers.
Innovation Solution
A chemically amplified negative resist composition incorporating a polymer with recurring units of fluorinated carboxylic acid onium salt, which acts as a base polymer soluble in alkaline developers and generates an acid catalyst, along with a nitrogen-containing compound, to improve acid diffusion uniformity and reduce substrate poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemically amplified negative resist compositions are used, then the basic patterning function is achieved, but line edge roughness increases and substrate poisoning occurs when forming patterns with feature sizes of 0.1 μm or less
Solution Approach 1:
The patent modifies the chemical parameters of the resist composition by incorporating a polymer with carboxylic acid groups having pKa of 3.0 or less (stronger acidity) and adjusting the acid generator to produce acids with pKa of 5.0 or less. This parameter change in acid strength and diffusion characteristics reduces line edge roughness while minimizing substrate poisoning effects during high-resolution patterning.
Solution Approach 2:
The patent creates a composite resist system combining: (1) a polymer with carboxylic acid groups (providing solubility control and etch resistance), (2) an acid generator (producing the catalytic acid), and (3) a crosslinker (forming the insoluble pattern). This composite material approach balances multiple functions to achieve low LER and reduced substrate poisoning simultaneously.
2Strength
If the resist film is thinned to achieve high etch resistance, then the pattern durability improves, but the feature size reduction becomes difficult
Solution Approach 1:
The patent changes the chemical composition parameters of the resist to achieve high etch resistance without increasing film thickness. Specifically, the polymer with carboxylic acid groups (pKa ≤ 3.0) provides enhanced etch resistance at molecular level, allowing thin films to maintain structural integrity during etching while supporting sub-0.1 μm feature sizes.
3Ease of operation
If phenolic units are used in the polymer for KrF lithography, then the alkali solubility is achieved, but the transmissivity to ArF exposure light (150-220 nm) is lost
Solution Approach 1:
The patent changes the polymer chemistry from phenolic units to polymers with carboxylic acid groups having pKa of 3.0 or less. This parameter change maintains alkali solubility (for developer compatibility) while removing the UV absorption issue, enabling transmissivity to ArF and EUV wavelengths for high-resolution lithography.
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 reduced LER and minimized substrate poisoning, enhancing the resolution and etch resistance of the resist patterns, especially when exposed to high-energy radiation like EUV or electron beams.
Implementation Method 1
an acid generator which is decomposed to generate an acid upon exposure to light
Implementation Method 2
a nitrogen-containing compound as a basic component... controlling the diffusion of the acid generated upon light exposure
Implementation Method 3
a polymer with recurring units of fluorinated carboxylic acid onium salt, which acts as a base polymer soluble in alkaline developers and generates an acid catalyst
Data Source
AI summary
A chemically amplified negative resist composition is provided comprising (A) an alkali-soluble base polymer, (B) an acid generator, and (C) a nitrogen-containing compound, the base polymer (A) turning alkali insoluble under the catalysis of acid. A polymer having a fluorinated carboxylic acid onium salt on a side chain is included as the base polymer. Processing the negative resist composition by a lithography process may form a resist pattern with advantages including uniform low diffusion of acid, improved LER, and reduced substrate poisoning.