Oxide TFT Light-Emitting Structure for Stable High-Speed Driving
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Solution Overview
Problem
Thin film transistors with oxide semiconductor films face challenges in achieving high operation speed and stable electric characteristics, particularly in driver circuits, where low channel length and high channel width lead to reduced switching characteristics and increased capacity load, while also requiring reduced variation in electrical characteristics.
Innovation Solution
A light-emitting device structure incorporating a thin film transistor with a bottom-gate inverted staggered channel-etched structure, utilizing an oxide semiconductor layer sandwiched between a gate electrode and a conductive layer, along with an oxide insulating layer, and a method for manufacturing that includes dehydration or dehydrogenation of the oxide semiconductor layer to control threshold voltage and reduce variation in electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the channel length is reduced to increase operation speed, then the operation speed is improved, but the switching characteristic (on-off ratio) is lowered
Solution Approach 1:
The patent applies parameter changes by modifying the oxide semiconductor layer properties through dehydration and dehydrogenation treatments. This changes the electrical characteristics of the semiconductor layer, enabling high operation speed while maintaining stable threshold voltage and good switching characteristics, thus resolving the contradiction between speed and reliability
2Speed
If the channel width is increased to increase operation speed, then the operation speed is improved, but the capacity load is increased
Solution Approach 1:
The patent changes the electrical parameters of the oxide semiconductor layer through dehydration and dehydrogenation, which improves carrier mobility and reduces threshold voltage variation. This allows for reduced channel width while maintaining operation speed, thereby decreasing capacity load
3Reliability
If dehydration or dehydrogenation treatment is applied to control threshold voltage, then threshold voltage variation is reduced, but manufacturing process complexity is increased
Solution Approach 1:
The patent applies preliminary action by performing dehydration and dehydrogenation treatments on the oxide semiconductor layer before forming the source and drain electrodes. This preliminary treatment stabilizes the threshold voltage early in the manufacturing process, reducing variation in final device characteristics while organizing the process flow efficiently
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 a light-emitting device with transistors that have stable electric characteristics, reduced threshold voltage variation, and improved reliability, allowing for high-speed operation and efficient light-emitting performance.
Implementation Method 1
dehydration or dehydrogenation of the oxide semiconductor layer to control threshold voltage
Implementation Method 2
dehydration or dehydrogenation of the oxide semiconductor layer to control threshold voltage
Data Source
AI summary
An object is to improve reliability of a light-emitting device. Alight-emitting device has a driver circuit portion including a transistor for a driver circuit and a pixel portion including a transistor for a pixel over one substrate. The transistor for the driver circuit and the transistor for the pixel are inverted staggered transistors each including an oxide semiconductor layer in contact with part of an oxide insulating layer. In the pixel portion, a color filter layer and a light-emitting element are provided over the oxide insulating layer. In the transistor for the driver circuit, a conductive layer overlapping with a gate electrode layer and the oxide semiconductor layer is provided over the oxide insulating layer. The gate electrode layer, a source electrode layer, and a drain electrode layer are formed using metal conductive films.