Alicyclic Polymer Gate Insulation for Organic TFTs
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Solution Overview
Problem
Current methods for manufacturing organic thin-film transistors (TFTs) face challenges in creating a gate insulation layer that balances high semiconductor characteristics with low hygroscopicity, heat resistance, and resistance to dielectric breakdown, particularly when the layer is made thin.
Innovation Solution
A method involving the use of a polymer from an alicyclic compound dissolved in a paraffin hydrocarbon solvent, which forms a nonpolar gate insulation layer, preventing diffusion of organic semiconductor and gate electrode materials, and maintaining a low water absorption to suppress ion diffusion and dielectric breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the gate insulation layer is made thin to improve TFT characteristics, then the ON/OFF ratio and S value improve, but dielectric breakdown occurs more frequently
Solution Approach 1:
The patent changes the chemical composition parameters of the gate insulation layer by using a polymer of an alicyclic compound (such as cycloolefin polymer) instead of conventional polymers. This material substitution fundamentally alters the dielectric properties, enabling the layer to withstand high voltages even at thin thicknesses (50-200 nm), thus resolving the contradiction between achieving good TFT characteristics and preventing dielectric breakdown.
Solution Approach 2:
The patent employs a composite approach by combining the polymer of an alicyclic compound with specific solvents (paraffin hydrocarbon, aromatic hydrocarbon, or ester) to create an application liquid that forms a gate insulation layer with optimized properties. This composite material system achieves both the thinness required for good TFT characteristics and the dielectric strength required to prevent breakdown.
2Temperature
If a polymer with high heat resistance is used for the gate insulation layer, then heat resistance improves, but the polymer becomes hard to dissolve in solvents
Solution Approach 1:
The patent selects polymers of alicyclic compounds (such as cycloolefin polymers like ZEONEX or ACRICYN) that inherently possess high heat resistance with glass transition temperatures above 100°C. These materials maintain their structural integrity at elevated temperatures while simultaneously being soluble in the specified solvents, thus resolving the contradiction between heat resistance and solubility.
Solution Approach 2:
The patent achieves both high heat resistance and good solubility by carefully selecting specific types of alicyclic polymer compounds and matching them with appropriate solvents. The local chemical structure of these polymers (cyclic carbon-hydrogen backbone) provides inherent thermal stability while the molecular weight and side chain configuration allow for controlled dissolution in the specified solvent systems.
3Ease of manufacture
If PMMA is used as the gate insulation layer material, then the layer can be formed easily, but high hygroscopicity causes deterioration of TFT characteristics
Solution Approach 1:
The patent fundamentally changes the chemical composition from polar polymers like PMMA to nonpolar or low-polarity polymers of alicyclic compounds. This compositional change reduces the hygroscopicity from PMMA's high water absorption to below 0.1% for the alicyclic polymers, thereby preventing TFT characteristic deterioration while maintaining ease of formation through solution processing.
4Ease of manufacture
If polystyrene is used as the gate insulation layer material, then the layer can be formed by coating process, but dielectric breakdown occurs immediately in the atmosphere
Solution Approach 1:
The patent develops a composite material system using polymers of alicyclic compounds combined with specific solvents that can be applied by coating processes. The resulting gate insulation layer maintains the ease of coating formation while achieving superior dielectric breakdown resistance, eliminating the immediate breakdown issue observed with polystyrene.
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
This approach results in a semiconductor device with improved semiconductor characteristics, high heat resistance, and reliability, without causing dielectric breakdown, enabling the production of high-performance semiconductor circuits and electronic devices.
Implementation Method 1
The gate insulation layer can thus include a nonpolar substance and a nonpolar solvent, preventing an organic semiconductor material and a gate electrode material from diffusing into the gate insulation layer
Implementation Method 2
forming a gate insulation layer including the polymer of the alicyclic compound by removing the paraffin hydrocarbon solvent from the application liquid
Implementation Method 3
maintaining a low water absorption to suppress ion diffusion and dielectric breakdown
Data Source
AI summary
A method for manufacturing a semiconductor device includes: forming a source electrode and a drain electrode on a substrate; forming an organic semiconductor layer including a π conjugated organic compound at least between the source electrode and the drain electrode; applying an application liquid on the organic semiconductor layer, the application liquid being made of a polymer of an alicyclic compound dissolved in a paraffin hydrocarbon solvent that is a carbocyclic compound without having aromaticity; forming a gate insulation layer including the polymer of the alicyclic compound by removing the paraffin hydrocarbon solvent from the application liquid; and forming a gate electrode on the gate insulation layer.