Hardmask Composition for Semiconductor Etching Selectivity
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Solution Overview
Problem
Conventional lithography processes face challenges in transferring patterns effectively due to insufficient resistance of the resist layer during etching, especially when dealing with ultrathin film resist layers, thick underlying layers, large etching depths, or specific etchants, necessitating a hard mask layer for pattern transfer but often resulting in inadequate etching selectivity and pattern fidelity.
Innovation Solution
A hard mask composition comprising a solvent and a compound with a specific structural unit, represented by Chemical Formula 1, is used to form a hard mask layer through spin-on-coating, which enhances pattern transfer by providing improved resistance and selectivity during etching, and includes additives like surfactants and cross-linking agents to ensure stable solubility and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resist layer is used for pattern transfer, then the pattern can be formed on the substrate, but the resist layer does not provide sufficient resistance during etching, especially for ultrathin film resist layers, thick underlying layers, or large etching depths
Solution Approach 1:
The patent divides the single resist layer into two separate functional layers: a resist layer for pattern formation and a hard mask layer for etching protection. This segmentation allows each layer to be optimized for its specific function, with the hard mask layer providing sufficient etching resistance without compromising the resist layer's patterning capability.
Solution Approach 2:
The hard mask layer acts as an intermediary layer between the resist layer and the underlying material layer. It receives the pattern from the resist layer and provides the necessary resistance during etching, mediating between the soft resist and the hard underlying layer to enable effective pattern transfer.
2Reliability
If a hard mask layer is added between the resist layer and the material layer, then etching resistance is improved, but the etching selectivity and pattern fidelity become inadequate
Solution Approach 1:
The patent modifies the chemical composition parameters of the hard mask layer by incorporating specific compounds (compounds 1 to 6) with controlled concentrations (1-20 wt%). This parameter optimization ensures the hard mask layer has sufficient etching resistance while maintaining appropriate etching selectivity and pattern fidelity. The solvent system (combining PGMEA and cyclohexanone in specific ratios) further fine-tunes the layer properties.
Solution Approach 2:
The hard mask layer is formulated as a composite material containing a specific combination of compounds (1-6), solvents (PGMEA and cyclohexanone), and optional additives (surfactants, cross-linking agents). This composite structure provides synergistic effects that simultaneously achieve high etching resistance, good etching selectivity, and excellent pattern fidelity.
3Productivity
If the etching depth is increased or the underlying layer is made thicker, then the pattern transfer capability is improved, but the resist layer's insufficient resistance becomes more problematic
Solution Approach 1:
The patent segments the protective function into two layers: the resist layer for shallow pattern definition and the hard mask layer for deep etching protection. This allows the etching depth to be increased without compromising resistance, as the hard mask layer specifically addresses the resistance requirement for deep or thick-layer etching.
Solution Approach 2:
The hard mask layer serves as an intermediary that enables deep pattern transfer by providing the necessary resistance for etching through thick underlying layers or to great depths, while allowing the resist layer to focus on precise pattern formation.
Data Source
AI summary
A hard mask composition, a method of forming a pattern, and a semiconductor integrated circuit device, the hard mask composition including a solvent; and a compound, the compound including a structural unit represented by the following Chemical Formula 1: