Fluorinated Alkyl Resist for ArF Lithography Pattern Collapse
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Solution Overview
Problem
In ArF lithography, conventional polymers used as resist materials face challenges such as pattern collapse during development and high mask error factor (MEF) due to swelling, which are exacerbated by the use of carboxylic acids as adhesives, and existing polymers struggle to maintain high resolution and sensitivity while minimizing these issues.
Innovation Solution
A chemically amplified positive resist composition is developed using a polymer with specific fluorinated alkyl alcohol and tertiary alkyl ester structures, which increases alkaline dissolution rates and incorporates lactone groups to enhance adhesion and control acid diffusion, thereby reducing pattern collapse and MEF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carboxylic acids are used as adhesive groups to enhance adhesion, then adhesion is improved, but swelling during development increases leading to pattern collapse and high MEF
Solution Approach 1:
The patent changes the chemical parameters of the adhesive group from carboxylic acid to fluorinated alkyl alcohol with specific pKa value (3-6), which fundamentally alters the interaction with developer solutions, reducing swelling while maintaining adhesion
Solution Approach 2:
The patent uses composite polymer structures combining fluorinated alkyl alcohol groups with specific backbone structures (cycloolefin, norbornene, or acrylic units) to achieve both adhesion and swelling resistance simultaneously
2Manufacturing precision
If conventional polymers are used to maintain high resolution, then resolution is improved, but sensitivity and etching resistance deteriorate
Solution Approach 1:
The patent employs composite polymer architectures integrating multiple functional units: fluorinated alkyl alcohol for adhesion control, specific backbone structures for mechanical stability, and acid-labile groups for high sensitivity, achieving all three properties simultaneously
3Manufacturing precision
If acid-labile groups with high acid lability are used to reduce PEB dependence, then resolution is improved, but pattern collapse during development increases
Solution Approach 1:
The patent optimizes the acid lability parameter by selecting specific acid-labile groups (tert-butyl, isopropyl, t-amyl) with controlled acid elimination rates, balancing resolution enhancement with pattern stability during development
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 high resolution, sensitivity, and minimized pattern collapse, making it suitable for micropatterning in VLSI and photomask production with improved durability and accuracy.
Implementation Method 1
a polymer having a rate of dissolution in an alkaline developer that increases under the action of acid
Implementation Method 2
acid-catalyzed chemical amplification positive working resist materials are effective as disclosed in U.S. Pat. No. 4,491,628 and U.S. Pat. No. 5,310,619
Data Source
AI summary
A polymer of which dissolution rate in an alkaline developer increases under the action of acid comprises recurring units having formulae (1) and (2) wherein R1, R2, and R4 are H or methyl, R3 is difluoromethyl or trifluoromethyl, and X is tertiary alkyl. A resist composition comprising the polymer has a high sensitivity and resolution, decreased pattern collapse during development, and minimized MEF and is best suited as micropatterning material for the VLSI manufacture.