Hybrid TFT Gate Insulator Structure for Hydrogen-Stable Displays
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Solution Overview
Problem
Thin film transistors (TFTs) made from metal oxide semiconductors are susceptible to hydrogen impurities, which cause threshold voltage shifts under voltage/light bias conditions, affecting display performance.
Innovation Solution
A hybrid TFT structure is developed with different active layers and gate insulators, where the second gate insulator has a lower hydrogen concentration than the first, using materials like silicon oxide and silicon nitride to reduce hydrogen impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If metal oxide semiconductors are used for TFT fabrication, then high carrier mobility and low processing temperatures are achieved, but the TFTs become sensitive to hydrogen impurity causing threshold voltage shift
Solution Approach 1:
The patent changes the material parameter of the gate insulator from conventional materials to silicon oxide with specifically controlled low hydrogen concentration. This parameter change in the gate insulator material directly addresses the hydrogen sensitivity issue while maintaining the benefits of metal oxide semiconductor TFTs.
Solution Approach 2:
The patent employs a composite structure combining metal oxide semiconductor active layer with silicon oxide gate insulator. This composite material approach allows the system to benefit from high carrier mobility of metal oxide semiconductors while the silicon oxide gate insulator provides hydrogen impurity resistance, resolving the threshold voltage stability issue.
2Manufacturing precision
If display resolution is increased, then higher pixel density is achieved, but smaller transistors require lower power and reduced mura defects
Solution Approach 1:
The patent changes the hydrogen concentration parameter of the gate insulator to very low levels, which stabilizes the transistor characteristics. This stabilization enables smaller transistor design with lower power consumption while maintaining high display resolution and reducing mura defects.
Data Source
AI summary
An electronic device is provided. The electronic device includes a substrate, a first active layer, a second active layer, a first gate electrode, a first insulator, a second gate electrode, a second insulator, a first electrode electrically connected to the second active layer, and a second electrode. The first active layer is different from the second active layer in material. The first insulator is disposed between the first active layer and the first gate electrode. The second insulator is disposed between the second active layer and the second gate electrode. The second gate electrode is disposed between the first electrode and the second active layer. The second electrode is overlapped with at least part of the second active layer. The second electrode and the first gate electrode are the same in material.