Overcoat Composition for High-Fidelity Resist Pattern Transfer
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Solution Overview
Problem
Semiconductor device fabrication faces challenges in forming precise patterns and transferring them with high fidelity due to shrinking device footprints and feature spacings, requiring multiple complex and costly lithographic exposures and pattern transfers through multiple intermediate layers.
Innovation Solution
An overcoat composition comprising a polymer, a fluorine-free acid generator with a five-membered aromatic ring substituted with electron-withdrawing groups, a base quencher, and an organic solvent is used to form a solubility-shifted region in the resist, enabling precise patterning without multiple photolithography steps by using the overcoat and relief pattern as a combined etch mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple lithographic exposures and pattern transfers through multiple intermediate layers are used, then pattern fidelity is maintained, but process complexity and fabrication costs increase
Solution Approach 1:
The patent merges the overcoat layer and the first resist pattern into a combined etch mask system. The overcoat contains a solubility-shifting agent that modifies the solubility of the first resist, enabling both layers to function together as a single patterning unit during etching, thereby reducing the need for separate intermediate layers while maintaining pattern fidelity
Solution Approach 2:
The solubility-shifting agent is incorporated into the overcoat layer before the patterning process begins. This preliminary incorporation allows the overcoat to actively participate in the patterning process by modifying resist solubility during development, rather than requiring additional separate processing steps after the initial patterning
2Manufacturing precision
If multiple lithographic exposures and pattern transfers through multiple intermediate layers are used, then pattern fidelity is maintained, but fabrication costs increase
Solution Approach 1:
The patent merges the overcoat layer and the first resist pattern into a combined etch mask system. The overcoat contains a solubility-shifting agent that modifies the solubility of the first resist, enabling both layers to function together as a single patterning unit during etching, thereby reducing the need for separate intermediate layers while maintaining pattern fidelity
Solution Approach 2:
The overcoat layer serves multiple functions: it acts as a protective coating during processing, contains the solubility-shifting agent that modifies resist properties, and functions as part of the etch mask system. This multi-functionality eliminates the need for separate intermediate layers, reducing fabrication costs while maintaining pattern fidelity
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
Enables high-fidelity patterning with advanced features like anti-spacer patterning and narrow line cuts, reducing process complexity and cost by integrating into conventional semiconductor fabrication workflows.
Implementation Method 1
diffusing a portion of the plurality of acid species into the first resist to form a solubility-shifted region of the first resist
Implementation Method 2
activating the fluorine-free acid generator to form a plurality of acid species within the overcoat layer
Data Source
AI summary
An overcoat composition includes a polymer, a fluorine-free acid generator, a base quencher, and an organic solvent. The fluorine-free acid generator includes a five-membered aromatic ring substituted with one or more electron-withdrawing groups.