EUV Positive Resist Copolymer for Fine Pattern Resolution
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Solution Overview
Problem
Current EUV lithography techniques face challenges in efficiently forming fine resist patterns with high resolution, as they often result in surface roughness and defects such as missing contact holes, and do not adequately address Critical Dimension (CD), Line Width Roughness (LWR), Line Edge Roughness (LER), and Local Critical Dimension Uniformity (LCDU).
Innovation Solution
A positive resist composition for EUV lithography is developed, comprising a copolymer with specific monomer units (A) and (B) and a weight-average molecular weight greater than 100,000, optimized to include a 1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl α-chloroacrylate unit and α-methylstyrene unit, with a molecular weight distribution and monomer proportion that enhances sensitivity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional copolymers are used as positive resist in EUV lithography, then the resist can be formed, but the resolution and surface roughness are insufficient
Solution Approach 1:
The patent changes the molecular weight parameter of the copolymer from conventional ranges to specifically more than 100,000, and adjusts the monomer composition parameters by incorporating specific units (formula I with halogen/cyano/alkylsulfonyl/alkoxy/nitro/acyl/alkyl ester groups and formula II with alkyl/halogen/hydroxyl/carboxyl/halogenated carboxyl groups). This parameter optimization enables the resist to achieve both high resolution and reduced surface roughness simultaneously.
Solution Approach 2:
The patent creates a composite resist material by combining specific monomer units (A and B) in a copolymer structure. The copolymer integrates multiple functional groups that work synergistically: monomer unit (A) provides sensitivity to EUV radiation while monomer unit (B) contributes to chain scission and solubility changes during development. This composite approach resolves the contradiction between resolution and surface roughness.
2Measurement precision
If higher molecular weight copolymer is used to improve resolution, then CD and LER improve, but the resist composition becomes more complex
Solution Approach 1:
The patent sets specific parameter ranges for the copolymer: weight-average molecular weight greater than 100,000, with controlled monomer ratios. By defining these parameters, the patent achieves precise control over CD and LER while avoiding excessive structural complexity. The specific monomer units (A and B) are designed to be relatively simple structures that polymerize into the desired molecular weight range without requiring complex synthesis procedures.
3Reliability
If the copolymer has optimized monomer composition for sensitivity, then EUV sensitivity improves, but the manufacturing process becomes more difficult
Solution Approach 1:
The patent specifies particular functional groups for the monomer units that enhance EUV sensitivity: halogen atoms, cyano groups, alkylsulfonyl groups, alkoxy groups, nitro groups, acyl groups, and alkyl ester groups in monomer unit (A), and alkyl, halogen, hydroxyl, carboxyl, or halogenated carboxyl groups in monomer unit (B). These parameter specifications ensure high sensitivity while the monomers themselves remain manufacturable through standard polymerization techniques.
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 solution enables the efficient formation of fine resist patterns with improved resolution and reduced surface roughness, achieving better CD, LWR, LER, and LCDU values, thereby enhancing the precision of EUV lithography.
Implementation Method 1
Copolymers that display increased solubility in a developer after undergoing main chain scission through irradiation with ionizing radiation, such as an electron beam, or short-wavelength light, such as ultraviolet light
Data Source
AI summary
Provided is a positive resist composition that can be used for efficiently forming a fine resist pattern with high resolution in an EUV lithography technique. The positive resist composition for extreme ultraviolet lithography contains a copolymer having a weight-average molecular weight of more than 100,000 and including monomer units (A) and (B) represented by formulae (I) and (II), shown below. In formula (I), X is a halogen atom, etc., L is a single bond or divalent linking group, and Ar is an optionally substituted aromatic ring group. In formula (II), R1 is an alkyl group, R2 is an alkyl group, halogen atom, haloalkyl group, hydroxyl group, carboxyl group, or halogenated carboxyl group, p is an integer of not less than 0 and not more than 5, and in a case in which more than one R2 is present, each R2 may be the same or different.