Norbornene Interlayer for Fluoropolymer Adhesion in OFETs
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Solution Overview
Problem
Conventional fluoropolymers used in electronic devices, such as Cytop and Teflon AF, face challenges in mass production due to poor integration, adhesion, and structural integrity, leading to issues like cracking and wrinkling during processing, which affect the reliability and efficiency of organic field effect transistors (OFETs).
Innovation Solution
The use of norbornene-type polymers as interlayers in electronic devices, which provide improved adhesion, structural integrity, and surface energy, addressing the limitations of traditional fluoropolymers by forming a stable interface with both organic and inorganic semiconductor materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoropolymers (e.g., Cytop, Teflon AF) are used as gate insulator layers, then low dielectric constant (k < 3.0) is achieved, but adhesion to substrate and OSC layer is poor
Solution Approach 1:
The patent introduces an interlayer comprising a polycycloolefin polymer between the fluoropolymer gate insulator layer and the substrate/OSC layer. This interlayer acts as a mediator that improves adhesion while maintaining the low dielectric constant property of the fluoropolymer. The polycycloolefin polymer has functional groups that can bond to both the fluoropolymer and the underlying layers, solving the adhesion problem without compromising the dielectric performance.
Solution Approach 2:
The patent creates a composite structure by combining the fluoropolymer gate insulator layer with a polycycloolefin polymer interlayer. This composite material approach allows the system to exhibit both the low dielectric constant of the fluoropolymer and the improved adhesion properties of the polycycloolefin polymer, resolving the contradiction between these two properties.
2Ease of manufacture
If fluoropolymers with low Tg (e.g., Cytop series, Tg ≈ 100-130°C) are used, then good processability is achieved, but cracking occurs during sputtering due to built-in stress
Solution Approach 1:
The patent applies a polycycloolefin polymer interlayer beforehand to cushion and distribute the built-in stress that develops during sputtering of the gate electrode. This interlayer prevents cracking of the fluoropolymer gate insulator layer by absorbing and distributing the mechanical stress, thereby maintaining structural integrity while preserving the good processability of the low Tg fluoropolymer.
3Reliability
If fluoropolymers with higher Tg (e.g., Teflon AF series, Tg = 240°C) are used, then cracking and wrinkling are avoided, but coating of substrates is poor and adhesion to additional layers is limited
Solution Approach 1:
The patent introduces a polycycloolefin polymer interlayer as a mediator between the high Tg fluoropolymer and the substrate/additional layers. This interlayer improves coating quality and adhesion while the fluoropolymer maintains its structural integrity. The polycycloolefin polymer has better wetting and adhesion properties that compensate for the poor coating behavior of high Tg fluoropolymers.
4Reliability
If conventional fluoropolymers are used in mass production, then low dielectric constant is maintained, but poor integration into processing and limited structural integrity reduce productivity
Solution Approach 1:
The patent introduces a polycycloolefin polymer interlayer that serves as a processing intermediary, enabling better integration into mass production workflows. This interlayer improves adhesion, prevents defects during subsequent processing steps, and enhances structural integrity, thereby increasing productivity while maintaining the low dielectric constant property of the fluoropolymer gate insulator layer.
Data Source
AI summary
Embodiments in accordance with the present invention provide for the use of polycycloolefins in electronic devices and more specifically to the use of such polycycloolefins as interlayers applied to fluoropolymer layers used in the fabrication of electronic devices, the electronic devices that encompass such polycycloolefin interlayers and processes for preparing such polycycloolefin interlayers and electronic devices.