Acetal-Based Photoresist Polymer for Low-Dose EUV Patterning
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Solution Overview
Problem
EUV lithography processes require higher exposure doses and longer times due to reduced photon sensitivity of conventional chemical amplified resists (CARs) when using EUV light, leading to challenges in fine patterning for semiconductor devices.
Innovation Solution
Development of an acetal-based polymer with an acid-labile functional group in the main chain, which undergoes main-chain scission upon exposure, reducing molecular weight and increasing photosensitivity through reversible addition-fragmentation chain transfer (RAFT) polymerization and chain extension reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chemical amplified resist (CAR) is used in EUV lithography, then the resist can be processed with existing materials, but the photosensitivity decreases due to reduced photon number at higher EUV energy
Solution Approach 1:
The patent changes the chemical composition parameters of the resist by introducing acetal-based polymers with specific molecular structures (Formulas 1-3) containing acid-labile groups. This chemical parameter change enables main-chain scission upon acid generation, dramatically improving photosensitivity and reducing required exposure dose from conventional CAR levels.
Solution Approach 2:
The patent creates a composite resist system combining acetal-based polymer (main chain with acid-labile groups), carboxylic acid-based polymer (solubility control), and photoacid generator (acid source). This composite material approach synergistically improves photosensitivity while maintaining processability and reducing exposure dose requirements.
2Quantity of substance
If higher exposure dose is applied to increase photon number, then the number of photons capable of generating acid increases, but the exposure time increases significantly
Solution Approach 1:
The patent introduces dynamic molecular weight changes through main-chain scission mechanism. Upon EUV exposure, acid generation triggers cleavage of acetal bonds, dynamically reducing polymer molecular weight and increasing solubility contrast. This dynamic response amplifies the effect of limited photons, improving photosensitivity and reducing required exposure time.
Solution Approach 2:
The resist system undergoes parameter changes in molecular weight (Mw reduction via scission) and solubility (increased contrast after exposure). These parameter changes are triggered by acid generation from limited photons, enabling efficient pattern formation with reduced exposure time.
3Stability of the object's composition
If conventional CAR is used, then the existing lithography process can be maintained, but line edge roughness increases and developing contrast decreases
Solution Approach 1:
The patent segments the polymer chain into smaller units through main-chain scission at acetal bonds. This segmentation reduces line edge roughness by creating more uniform, smaller molecular fragments that dissolve more uniformly during development, improving manufacturing precision while maintaining process compatibility.
Solution Approach 2:
The resist exhibits dynamic molecular weight reduction upon exposure, transitioning from high Mw (low roughness) to lower Mw (high contrast). This dynamic transformation improves line edge definition and reduces roughness while maintaining compatibility with existing lithography processes.
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 acetal-based polymer enhances photosensitivity and reduces line edge roughness, improving developing contrast and sensitivity with reduced exposure doses, suitable for fine patterning in semiconductor manufacturing.
Implementation Method 1
an acetal-based polymer with an acid-labile functional group in the main chain, which undergoes main-chain scission upon exposure
Implementation Method 2
a photoacid generator, wherein the base polymer includes the acetal-based polymer
Data Source
AI summary
An acetal-based compound represented by Formula 1, an acetal-based prepolymer, an acetal-based polymer, and a photoresist composition including the samewherein in Formula 1, R1 to R10, G, a, and b are as defined in the detailed description, and * indicates a linking site.