Dual-TFT Display Substrate for Holding Capacity and Threshold Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display technologies face limitations in achieving low power consumption and high mobility characteristics for portable and wearable devices due to the restrictions of current thin film transistor technologies.
Innovation Solution
A thin film transistor substrate is designed with two different types of transistors, one using polycrystalline semiconductor material for driver ICs and another using oxide semiconductor material for switching elements, optimized through minimized mask processes and controlled hydrogenation to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single thin film transistor with high capacitance gate insulating layer is used, then the holding capacity is improved, but the threshold voltage control becomes difficult and manufacturing precision deteriorates
Solution Approach 1:
The gate insulating layer is divided into two separate layers: a first gate insulating layer (high-k material like铪氧化物) and a second gate insulating layer (low-k material like硅氧化物). This segmentation allows each layer to perform its specialized function - the first layer provides high capacitance for holding capacity while the second layer enables precise threshold voltage control, resolving the contradiction between these two requirements.
2Reliability
If multiple thin film transistors with different structures are used, then both holding capacity and threshold voltage control are improved, but device complexity increases
Solution Approach 1:
Two thin film transistors with different gate insulating layer structures are combined into a single integrated device. The first TFT uses a high-k gate insulating layer for holding capacity, while the second TFT uses a low-k gate insulating layer for threshold voltage control. This merging approach achieves the benefits of both structures while reducing overall device complexity compared to using separate transistors.
Solution Approach 2:
The gate insulating layer structure is designed to perform multiple functions through its two-layer configuration. The same gate insulating layer structure serves both as a high-capacitance layer for data holding and as a controllable threshold voltage layer, enabling the device to achieve both functions within a unified structure rather than requiring separate specialized components.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A thin film transistor substrate includes a first thin film transistor disposed having a polycrystalline semiconductor layer, a first gate electrode on the polycrystalline semiconductor layer, a first source electrode and a first drain electrode; a first gate insulating layer between the polycrystalline semiconductor layer and the first gate electrode; a second thin film transistor disposed having an oxide semiconductor layer on the first gate electrode, a second gate electrode on the oxide semiconductor layer, a second source electrode and a second drain electrode; an intermediate insulating layer disposed on the first gate electrode and under the oxide semiconductor layer; and a second gate insulating layer on the intermediate insulating layer and under the first source electrode, the first drain electrode and the second gate electrode.