Hybrid TFT Substrate with Polycrystalline and Oxide Layers
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Solution Overview
Problem
Current display technologies face challenges in achieving low power consumption and efficient manufacturing processes for flat panel displays, particularly in developing portable and wearable devices, where existing thin film transistor substrates with multiple types of transistors are limited by high power consumption and complex manufacturing processes.
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 for low power consumption and efficient manufacturing by employing a top-gate structure for polycrystalline transistors and a bottom-gate structure for oxide transistors, along with hydrogenation and thermal treatment processes to stabilize the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single type of thin film transistor is used on the substrate, then the manufacturing process is simplified, but the power consumption cannot be optimized for portable devices
Solution Approach 1:
The substrate is divided into two distinct regions: a first region containing first thin film transistors with polycrystalline semiconductor layers for driver ICs requiring high current drive capability, and a second region containing second thin film transistors with oxide semiconductor layers for switching elements requiring low leakage current. This segmentation allows each transistor type to be optimized for its specific function while sharing the same substrate and manufacturing process
Solution Approach 2:
Different semiconductor materials are selectively applied to different regions of the substrate based on functional requirements. The first region uses polycrystalline semiconductor material for high mobility applications, while the second region uses oxide semiconductor material for low power consumption applications. This local differentiation enables simultaneous optimization of both current drive capability and power efficiency
2Use of energy by moving object
If multiple types of thin film transistors are formed on the substrate to optimize power consumption, then power consumption is reduced, but the manufacturing process complexity increases
Solution Approach 1:
A single amorphous semiconductor layer serves multiple functions: it acts as the precursor material for both polycrystalline and oxide semiconductor regions, and the same gate insulating layer structure serves as both the gate dielectric for first transistors and the base for oxide semiconductor formation in the second region. This multi-functionality reduces the number of separate manufacturing steps
Solution Approach 2:
The amorphous semiconductor layer is formed first across the entire substrate before any crystallization or oxide conversion processes. This preliminary formation establishes a uniform base layer that can subsequently be selectively transformed into different semiconductor types through targeted thermal or chemical treatments, simplifying the overall manufacturing sequence
3Power
If polycrystalline semiconductor material is used for driver ICs, then the current drive capability is improved, but the manufacturing process requires additional crystallization steps
Solution Approach 1:
The crystallization process for forming polycrystalline semiconductor regions is merged with the thermal treatment process used for other substrate preparations. By conducting the crystallization step simultaneously with existing thermal processing operations, the patent eliminates dedicated crystallization steps while still achieving the required polycrystalline structure for high current drive capability
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 results in a substrate with optimized functionality for portable and wearable displays, achieving low power consumption, reduced manufacturing complexity, and improved video quality without flickering, even at lower frame rates, thereby extending battery life and enhancing display performance.
Implementation Method 1
hydrogenation and thermal treatment processes to stabilize the semiconductor layers
Implementation Method 2
hydrogenation and thermal treatment processes to stabilize the semiconductor layers
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided are a thin film transistor (TFT) substrate and a display using the same. A TFT substrate includes: a substrate, a first TFT on the substrate, including: a polycrystalline semiconductor layer, a first gate electrode thereover, a first source electrode, and a first drain electrode, a second TFT on the substrate, including: a second gate electrode, an oxide semiconductor layer on the second gate electrode, a second source electrode, and a second drain electrode, an intermediate insulating layer including a nitride layer, on the first gate electrode, and an oxide layer covering the second gate electrode, on the intermediate insulating layer, on the oxide layer, and overlapping the second gate electrode, wherein the first source, first drain, and second gate electrodes are between the intermediate insulating layer and the oxide layer, and wherein the second source and the second drain electrodes are on the oxide semiconductor layer.