TFT Substrate with Nitride Barrier for OLED Stability
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Solution Overview
Problem
Current technologies face challenges in maintaining the stability and reliability of oxide semiconductor thin film transistors in organic light-emitting diode displays, especially due to light-induced degradation and the difficulty in ensuring high current-driving characteristics with low power consumption, which is crucial for portable and wearable devices.
Innovation Solution
A thin film transistor substrate is designed with a combination of oxide semiconductor and polycrystalline semiconductor materials, featuring a top-gate and bottom-gate structure respectively for the switching and driving transistors, and an intermediate nitride layer to control hydrogen diffusion, minimizing contact holes and optimizing channel area characteristics for high-density and low-power displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxide semiconductor thin film transistors are used in organic light-emitting diode displays, then low power consumption and high current-driving characteristics can be achieved, but light-induced degradation reduces stability and reliability
Solution Approach 1:
A nitrogen-containing insulating layer is introduced as an intermediary between the oxide semiconductor layer and the overcoat layer. This intermediate layer acts as a diffusion barrier to prevent hydrogen from the overcoat layer from reaching the oxide semiconductor layer, thereby protecting the transistor from light-induced degradation while maintaining the low power consumption characteristics of oxide semiconductors
Solution Approach 2:
The patent converts the potentially harmful hydrogen diffusion that causes light-induced degradation into a beneficial protective mechanism. By introducing the nitrogen-containing insulating layer, hydrogen diffusion is blocked, transforming the original harmful effect into a protected state that maintains both reliability and energy efficiency
2Power
If oxide semiconductor thin film transistors are used, then high current-driving characteristics with low power consumption are achieved, but stability and reliability deteriorate due to light-induced degradation
Solution Approach 1:
The nitrogen-containing insulating layer serves as a protective intermediary that blocks hydrogen diffusion pathways. This allows the oxide semiconductor layer to maintain its superior current-driving characteristics and low power consumption while being protected from light-induced degradation that would otherwise reduce stability
Solution Approach 2:
The patent creates a composite structure combining the oxide semiconductor layer with the nitrogen-containing insulating layer. This composite configuration leverages the electrical properties of oxide semiconductors while adding the protective properties of nitrogen-containing materials, achieving both high performance and stability
3Ease of manufacture
If conventional thin film transistor structures are used, then manufacturing is simpler, but aperture ratio and density are limited
Solution Approach 1:
The patent segments the insulating layer structure into multiple functional layers: a gate insulating layer, a nitrogen-containing insulating layer, and an overcoat layer. This segmentation allows each layer to perform its specific function while maintaining manufacturing feasibility and achieving higher aperture ratios through optimized contact hole formation
Solution Approach 2:
The patent adds a new dimensional layer (the nitrogen-containing insulating layer) between existing layers to solve the aperture ratio limitation. This dimensional addition enables better control of contact hole formation and improves light emission area without significantly complicating the manufacturing process
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 configuration enhances the stability and reliability of thin film transistors, enabling ultra-high density organic light-emitting diode displays with high aperture ratio and reduced power consumption, suitable for portable and wearable devices.
Implementation Method 1
an intermediate insulating layer on the first gate electrode and the polycrystalline semiconductor layer, the intermediate insulating layer including a nitride layer
Implementation Method 2
The organic light-emitting diode radiates light due to energy from an exciton formed in an excitation state in which a hole (from the anode) and an electron (from the cathode) are recombined at the emission layer EML
Data Source
AI summary
Provided are a thin film transistor (TFT) substrate and a method of manufacturing the same. A TFT substrate includes: a substrate defining a pixel area, a first TFT including: an oxide semiconductor layer, a first gate electrode on the oxide semiconductor layer, a first source electrode, and a first drain electrode, a second TFT including: a second gate electrode, a polycrystalline semiconductor layer on the second gate electrode, a second source electrode, and a second drain electrode, a first gate insulating layer under the first gate electrode and the second gate electrode, the first gate insulating layer covering the oxide semiconductor layer, a second gate insulating layer under the polycrystalline semiconductor layer, the second gate insulating layer covering the first gate electrode and the second gate electrode, and an intermediate insulating layer on the first gate electrode and the polycrystalline semiconductor layer, the intermediate insulating layer including a nitride layer.