Thin Film Transistor Substrate with Dummy Layer for Low Power
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Solution Overview
Problem
Existing thin film transistor substrates for flat panel displays face challenges in achieving low power consumption and efficient manufacturing processes, particularly in developing portable and wearable devices, where the limitations of existing technologies hinder the integration of transistors with different characteristics on the same substrate.
Innovation Solution
A thin film transistor substrate is designed with two types of transistors, one using polycrystalline semiconductor material for driver ICs and the other using oxide semiconductor material for switching elements, optimized through a manufacturing process that minimizes mask processes and incorporates a dummy layer and intermediate insulating layers to manage hydrogen diffusion, allowing for efficient power management and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If two different types of transistors are integrated on the same substrate, then power consumption is reduced and video quality is improved, but the manufacturing process complexity increases
Solution Approach 1:
The substrate is divided into different regions: a first region containing transistors with polycrystalline semiconductor layers and a second region containing transistors with oxide semiconductor layers. This segmentation allows each region to be optimized for specific functions (driver circuits vs. pixel circuits) while maintaining a unified manufacturing process framework.
Solution Approach 2:
A unified manufacturing process is designed that can handle both polycrystalline and oxide semiconductor materials through common steps such as sputtering, annealing, and electrode formation. The process uses universal equipment and methodologies, reducing the need for separate manufacturing lines despite the diversity of transistor types.
2Manufacturing precision
If multiple mask processes are used to manufacture different transistor types, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The formation of source and drain electrodes for both polycrystalline and oxide semiconductor transistors is merged into a single sputtering process. A single mask pattern is used to define electrode regions for both transistor types simultaneously, eliminating the need for separate mask processes and significantly improving manufacturing efficiency.
Solution Approach 2:
The source and drain electrodes are formed preliminarily during the same sputtering process used for gate electrodes. This preliminary action allows subsequent transistor-specific processing to proceed more efficiently, as the basic electrode structure is already in place for both transistor types before region-specific annealing treatments.
3Ease of manufacture
If hydrogen diffusion is not controlled, then manufacturing process is simplified, but transistor reliability deteriorates
Solution Approach 1:
An intermediate insulating layer is introduced between the polycrystalline semiconductor layer and the oxide semiconductor layer. This intermediate layer serves as a hydrogen barrier, preventing hydrogen diffusion from the polycrystalline region to the oxide semiconductor region, thereby protecting transistor reliability while being integrated into the standard manufacturing process.
Solution Approach 2:
The potential harmful effect of hydrogen diffusion, which could degrade oxide semiconductor properties, is converted into a controlled process feature. By strategically placing the intermediate insulating layer, the manufacturing process itself becomes the mechanism for protecting transistor performance, turning a potential reliability issue into a built-in protection strategy.
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
The solution enables the creation of a substrate with optimized characteristics for portable and wearable displays, achieving low power consumption and improved video quality without flickering, suitable for applications in mobile and wearable devices.
Implementation Method 1
an intermediate insulating layer on the first gate electrode and the second gate electrode and under the oxide semiconductor layer
Implementation Method 2
a first semiconductor layer on the substrate and including a polycrystalline semiconductor material; depositing a gate insulating layer covering the first semiconductor layer
Data Source
AI summary
A thin film transistor substrate includes a substrate; a first thin film transistor on the substrate and including a polycrystalline semiconductor layer, a first gate electrode on the polycrystalline semiconductor layer, a first source electrode, and a first drain electrode; a second thin film transistor on the substrate and 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 on the first gate electrode and the second gate electrode and under the oxide semiconductor layer; and a dummy layer between the first source electrode and the intermediate insulating layer and between the first drain electrode and the intermediate insulating layer, wherein the dummy layer is formed of a same material as the oxide semiconductor layer.