Oxide Semiconductor TFT Wiring Structure for Oxygen Stability
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Solution Overview
Problem
Existing oxide semiconductors in TFTs face challenges in maintaining both initial characteristics and reliability over the product life due to oxygen migration, leading to unstable performance.
Innovation Solution
A TFT structure is designed with a laminated drain and source wiring configuration, incorporating a second oxide semiconductor layer under a metal layer, which stabilizes oxygen supply and confinement within the first oxide semiconductor, thereby maintaining consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the amount of oxygen in the insulating layer is increased to control initial characteristics, then the initial characteristics are improved, but defects in the insulating layer increase and reliability deteriorates
Solution Approach 1:
The insulating layer is divided into multiple layers: a first insulating layer containing oxygen that contacts the oxide semiconductor, and a second insulating layer with fewer defects formed above it. This segmentation allows each layer to serve different functions - the first layer provides oxygen for initial characteristics while the second layer maintains low defect density for reliability.
Solution Approach 2:
Different regions of the insulating structure have different oxygen concentrations and defect densities tailored to their specific functions. The first insulating layer has high oxygen content where it contacts the oxide semiconductor to establish initial characteristics, while the second insulating layer has lower oxygen content and fewer defects to maintain reliability over the product life.
2Manufacturing precision
If oxygen is controlled initially in the oxide semiconductor, then initial characteristics are improved, but oxygen migrates out during product life causing characteristics to change
Solution Approach 1:
The first insulating layer is pre-filled with oxygen during formation to compensate for future oxygen loss from the oxide semiconductor. This preliminary oxygen reservoir prevents oxygen depletion during the product life, maintaining stable characteristics without requiring excessive initial oxygen that would cause defects.
Solution Approach 2:
The first insulating layer acts as an oxygen reservoir or buffer between the oxide semiconductor and the external environment. It supplies oxygen to the oxide semiconductor during operation, preventing oxygen migration out of the semiconductor while maintaining stable oxygen concentration and characteristics.
3Device complexity
If a single insulating layer is used to cover the oxide semiconductor, then the structure is simple, but it cannot simultaneously provide optimal oxygen supply and maintain low defect density
Solution Approach 1:
The insulating layer is segmented into multiple functional layers with different compositions and oxygen concentrations. This segmentation enables the structure to simultaneously provide oxygen supply from the first layer while maintaining low defect density in the second layer, achieving both initial characteristics and long-term reliability.
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 structure ensures stable TFT characteristics by maintaining optimal oxygen levels, reducing defects, and enhancing reliability of the TFTs over the product life.
Implementation Method 1
even the amount of oxygen is controlled initially, the oxygen gradually moves out from the oxide semiconductor during the product life
Data Source
AI summary
The purpose of the present invention is to improve reliability of the TFT of the oxide semiconductor. The feature of the invention is: A display device comprising: a substrate including a display area where plural pixels are formed, the pixel includes a first TFT of a first oxide semiconductor, a first gate insulating film is formed under the first oxide semiconductor, a first gate electrode is formed under the first gate insulating film, an interlayer insulating film is formed on the first oxide semiconductor; a drain wiring, which connects with the first oxide semiconductor, and a source wiring, which connects with the first oxide semiconductor, are formed on the interlayer insulating film; the drain wiring or the source wiring is a laminated structure of a second oxide semiconductor and a first metal, the second oxide semiconductor is under the first metal.