Oxide TFT Dielectric Structure for Hydrogen Trapping in Displays
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Solution Overview
Problem
Excessive hydrogen introduction into oxide semiconductor layers in display devices increases carrier concentration, leading to deteriorated electrical properties and reliability of thin film transistors.
Innovation Solution
Incorporating a trap element like nitrogen, fluorine, or boron in dielectric films and gate electrodes to trap hydrogen, creating a gradient that prevents hydrogen from reaching the oxide semiconductor layer, thereby stabilizing the threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrogen is introduced into the oxide semiconductor layer, then carrier concentration increases, but electrical properties and reliability deteriorate
Solution Approach 1:
A dielectric film containing trap elements (nitrogen, fluorine, or boron) is introduced as an intermediary layer between the oxide semiconductor layer and hydrogen sources. This mediator traps hydrogen atoms before they can reach the oxide semiconductor layer, preventing hydrogen-induced carrier concentration increase while maintaining electrical properties. The trap elements create binding sites that capture and immobilize hydrogen, effectively blocking its migration path.
Solution Approach 2:
The invention converts the harmful effect of hydrogen (which normally degrades device reliability) into a beneficial trapping mechanism. By intentionally introducing trap elements that have high affinity for hydrogen, the hydrogen that would otherwise be harmful is now captured and utilized to fill trap sites, preventing it from reaching the oxide semiconductor layer and causing damage. The harmful hydrogen is thus transformed into a trapped, harmless state.
2Reliability
If dielectric films with trap elements are added to prevent hydrogen, then reliability improves, but device complexity increases
Solution Approach 1:
Instead of uniformly distributing trap elements throughout the entire dielectric structure, the invention applies trap elements locally in specific regions where hydrogen migration is most likely to occur. The dielectric film has non-uniform composition with trap elements concentrated in strategic locations, providing effective hydrogen protection while minimizing overall structural complexity and material usage.
Solution Approach 2:
The dielectric film is designed as a composite material combining standard dielectric materials with trap elements (nitrogen, fluorine, or boron). This composite structure integrates the electrical insulation properties of the dielectric material with the hydrogen-trapping capabilities of the trap elements, achieving dual functionality in a single layer rather than requiring separate protective layers.
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 approach effectively prevents hydrogen-induced conductivity in the channel region, stabilizing the threshold voltage and enhancing the reliability of thin film transistors in display devices.
Implementation Method 1
the upper region including a trap element configured to trap hydrogen
Data Source
AI summary
Disclosed is a display device and a method of manufacturing the same having improved reliability. In the display device, at least one of a plurality of dielectric films disposed between an oxide semiconductor layer and a light-emitting device includes a lower region disposed on the oxide semiconductor layer and an upper region disposed on the lower region, the upper region including a trap element configured to trap hydrogen, whereby reliability of a thin film transistor including the oxide semiconductor layer is improved.