Oxide TFT Display Insulating Layers for Threshold Shift Suppression
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Solution Overview
Problem
Display devices, particularly OLEDs, face challenges in preventing short circuits due to excessive hydrogen ions flowing into semiconductor channels, which can lower threshold voltages and cause defects in switching characteristics.
Innovation Solution
A display device structure is implemented with a first interlayer insulating layer made of silicon nitride, which has a controlled hydrogen release amount by adjusting the supply ratios of ammonia, nitrogen, and silane, and a second interlayer insulating layer of silicon oxide, to reduce hydrogen inflow and prevent short circuits, while also optimizing the binding ratios of nitrogen and hydrogen bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional interlayer insulating layer is used, then the device structure is simple, but hydrogen ions flow into semiconductor channels causing short circuits and threshold voltage shifts
Solution Approach 1:
The interlayer insulating layer is divided into multiple sub-layers with different materials and hydrogen release characteristics. This segmentation allows each sub-layer to perform specific functions in controlling hydrogen ion flow, thereby preventing short circuits while maintaining a manageable structural complexity through systematic design.
Solution Approach 2:
The patent employs composite interlayer insulating structures combining different materials (e.g., silicon oxide, silicon nitride, organic insulating materials) with complementary properties. This composite approach enables effective hydrogen ion blocking while preserving structural integrity and electrical performance, resolving the contradiction between reliability improvement and device complexity.
2Reliability
If the hydrogen release amount is increased to improve insulation, then more hydrogen ions are available to cause short circuits, but if decreased, then insulation effectiveness is reduced
Solution Approach 1:
The patent introduces intermediary insulating layers that act as barriers between the semiconductor channel and external hydrogen sources. These intermediary layers mediate hydrogen ion flow by providing controlled resistance, preventing excessive hydrogen ingress while maintaining adequate insulation, thus stabilizing threshold voltage without causing short circuits.
Solution Approach 2:
The patent optimizes parameters such as the thickness, material composition, and hydrogen content of interlayer insulating layers. By precisely controlling these parameters, the system achieves the optimal balance between hydrogen ion blocking capability and insulation effectiveness, preventing both short circuits and threshold voltage instability.
3Reliability
If multiple interlayer insulating layers are added to control hydrogen, then hydrogen flow is suppressed, but the manufacturing process becomes more complex
Solution Approach 1:
The multi-layer insulating structure is designed with segmentation, where each layer serves a specific function in the hydrogen control sequence. This functional segmentation enables systematic manufacturing processes, with each layer deposited using standardized techniques, thereby suppressing hydrogen flow while keeping the manufacturing process manageable through modular construction.
Solution Approach 2:
The interlayer insulating layers are designed to perform multiple functions simultaneously: electrical insulation, hydrogen ion blocking, and mechanical support. This multi-functionality reduces the need for additional specialized layers, thereby suppressing hydrogen flow and maintaining switching characteristic stability without proportionally increasing manufacturing complexity.
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 effectively suppresses hydrogen ion flow into semiconductor channels, shifting threshold voltages in a positive direction and preventing defects, thereby enhancing the reliability and performance of the display device.
Implementation Method 1
a release amount (intensity (A)) of the hydrogen of the first interlayer insulating layer may be at most about 2.0E-09 at a temperature of at least about 350° C.
Implementation Method 2
the nitrogen and hydrogen are combined through a first bond, the silicon and the hydrogen are combined through a second bond
Implementation Method 3
a second interlayer insulating layer disposed on the first interlayer insulating layer
Data Source
AI summary
A display device includes a base substrate including a display area and a non-display area around the display area are defined, a first interlayer insulating layer disposed on the base substrate, a second interlayer insulating layer disposed on the first interlayer insulating layer, a first semiconductor layer disposed on the second interlayer insulating layer and including an oxide, and a first gate insulating layer disposed on the first semiconductor layer, wherein the material of the first interlayer insulating layer and the material of the second interlayer insulating layer are different from each other. Methods of manufacturing a display device are also disclosed.