Low-Surface-Energy Additives for EUV Photoresist Contrast
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the loss of contrast in the patterned resist due to unwanted secondary electron exposure during EUV lithography, which affects the precision of feature sizes in semiconductor devices.
Innovation Solution
A novel additive with low surface energy is applied to the outermost surface of metallic resists to enhance chemical resistance, reducing the impact of ambient fab environment chemicals and improving the stability of the resist layer during EUV lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic resists are used in EUV lithography, then absorption of EUV photons is improved, but chemical resistance to ambient fab environment chemicals deteriorates
Solution Approach 1:
The patent applies a low surface energy coating layer over the metallic resist to create a composite structure. This coating layer provides chemical resistance to the resist while allowing the metallic resist underneath to maintain its EUV photon absorption properties, thus resolving the contradiction between absorption efficiency and chemical resistance.
Solution Approach 2:
The low surface energy coating acts as an intermediary layer between the metallic resist and the ambient fab environment chemicals. This intermediate layer protects the metallic resist from direct contact with harmful chemicals while not interfering with the EUV lithography process, thereby maintaining both absorption and chemical resistance.
2Device complexity
If no additive is applied to metallic resists, then process simplicity is maintained, but contrast in patterned resist deteriorates
Solution Approach 1:
The patent changes the surface energy parameter of the resist layer by applying a low surface energy coating. This parameter change enhances the chemical resistance and maintains contrast in the patterned resist, improving manufacturing precision without significantly complicating the overall process.
3Ease of manufacture
If metallic resists are used without protection, then ease of manufacture is maintained, but line width roughness increases
Solution Approach 1:
The patent applies a thin film coating with low surface energy over the metallic resist. This thin protective film prevents chemical interactions that would cause line width roughness, thereby improving manufacturing precision while keeping the ease of manufacture relatively high due to the simplicity of the coating application.
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 additive enhances the chemical resistance of metallic photoresists, leading to improved contrast and precision in patterned resists, thereby reducing line width roughness and critical dimension uniformity variations, thus enabling more precise semiconductor feature formation.
Implementation Method 1
The additive has low surface energy and covers an outermost surface of the metallic resists
Implementation Method 2
an exposure modifies the chemical and physical properties of the exposed regions of the photosensitive material
Data Source
AI summary
A lithography method comprises the following steps. A target layer is formed over a substrate. A photoresist composition is mixed with a first additive to form a mixture. The first additive is non-reactive to the photoresist composition and comprises fluorine, fluoalkyl, fluoaryl, silicon, silane, silanol, or fluorosilane. The mixture is applied over the target layer to form a photoresist layer. The photoresist layer is exposed. The photoresist layer is developed. The target layer is etched using the photoresist layer as an etch mask.