TFT Substrate With Nitride And Oxide Layers For Hydrogen Control
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Solution Overview
Problem
Existing display devices face limitations in implementing low power consumption, particularly in portable and wearable devices, due to challenges in optimizing the characteristics of thin film transistors on substrates.
Innovation Solution
A thin film transistor substrate is designed with two types of transistors on the same substrate, featuring a polycrystalline semiconductor layer and an oxide semiconductor layer, where a nitride layer is used to hydrogenate the polycrystalline semiconductor material while an oxide layer prevents excessive hydrogen from affecting the oxide semiconductor material, thereby optimizing power efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitride layer is used to hydrogenate the polycrystalline semiconductor material, then the mobility of the polycrystalline semiconductor is improved, but hydrogen may diffuse into the oxide semiconductor layer causing instability
Solution Approach 1:
An oxide layer is introduced as an intermediary barrier between the nitride layer and the oxide semiconductor layer. This oxide layer prevents hydrogen atoms from the nitride layer from diffusing into the oxide semiconductor layer, while allowing the polycrystalline semiconductor layer to receive hydrogen for mobility improvement. The oxide layer thus mediates the interaction between hydrogen source and sensitive components.
Solution Approach 2:
The device is segmented into distinct functional regions with different hydrogen requirements. The polycrystalline semiconductor layer is separated from the oxide semiconductor layer by the oxide layer, allowing independent optimization of hydrogen content in each region. This segmentation enables the polycrystalline layer to be hydrogenated for high mobility while protecting the oxide semiconductor layer from hydrogen-induced instability.
2Use of energy by stationary object
If different types of thin film transistors are disposed on the same substrate, then the display device can achieve low power consumption for low-speed drive, but the characteristics of each transistor type may be compromised
Solution Approach 1:
Different regions of the substrate are designed with locally optimized transistor structures. First thin film transistors use polycrystalline semiconductor layers hydrogenated for high mobility applications, while second thin film transistors use oxide semiconductor layers protected from hydrogen for low-power switching applications. Each region has tailored material composition and structure to meet its specific performance requirements.
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 performance of thin film transistors by minimizing hydrogen diffusion into the oxide semiconductor layer, leading to improved power consumption and stability, suitable for low-speed drive and low-power display devices.
Implementation Method 1
a nitride layer is used to hydrogenate the polycrystalline semiconductor material
Implementation Method 2
an oxide layer prevents excessive hydrogen from affecting the oxide semiconductor material
Data Source
AI summary
Provided are a thin film transistor (TFT) substrate, a display device, and a method of forming the TFT. A TFT substrate includes: a first TFT including: a polycrystalline semiconductor (PS) layer, a first gate electrode (GE) overlapping the PS layer, a nitride layer (NL) on the first GE, an oxide layer (OL) on the NL, and a first source electrode and a first drain electrode on the OL, and a second TFT including: a second GE on a same layer as the first GE, a hydrogen collecting layer between the second GE and the NL, an oxide semiconductor (OS) layer on the OL, a second source electrode and a second drain electrode contacting respective sides of the OS layer, wherein the first TFT and the second TFT are disposed on a same substrate, and wherein the NL includes an opening exposing the hydrogen collecting layer of the second TFT.