Silicon Oxynitride Film for Flexible Display Frame Wiring
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Solution Overview
Problem
In flexible organic EL display devices, there is a trade-off between reducing the taper angle of inorganic insulating films at bending sections to prevent wiring line breakage and reliably detecting the end point of dry etching, due to the overlap of silicon oxide films with plasma light emission, making it difficult to minimize both simultaneously.
Innovation Solution
The use of a silicon oxynitride film as the inorganic insulating film in the TFT layer, which allows for a reliable detection of the dry etching end point and reduces the taper angle by forming an opening through the film to expose the resin substrate, enabling the frame wiring line to be placed directly on the substrate, thus minimizing the taper angle and preventing film breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a silicon oxide film is used as the inorganic insulating film, then the taper angle can be reduced, but the end point of dry etching becomes hard to detect due to overlap with plasma light emission
Solution Approach 1:
A silicon oxynitride film is introduced as an intermediary layer between the silicon oxide film and the resin substrate. This intermediary layer has different plasma light emission characteristics that do not overlap with the detection wavelength, enabling reliable end point detection while allowing the silicon oxide film to maintain its low taper angle formation capability
Solution Approach 2:
The inorganic insulating film is formed as a composite structure combining silicon oxynitride and silicon oxide layers. The silicon oxynitride layer provides detection-friendly plasma characteristics, while the silicon oxide layer provides the desired low taper angle, creating a composite material system that achieves both contradictory requirements
2Reliability
If the inorganic insulating film is removed by dry etching at the bending section, then wiring line breakage is prevented, but the taper angle increases making wiring line placement difficult
Solution Approach 1:
The silicon oxynitride film acts as an intermediary that enables controlled removal of the inorganic insulating film at bending sections. Its distinct plasma emission characteristics allow precise etching control, preventing wiring line breakage while maintaining a manageable taper angle for subsequent wiring line formation
Solution Approach 2:
The inorganic insulating film structure is made non-uniform: the silicon oxynitride layer is removed at bending sections to prevent wiring line breakage, while the silicon oxide layer is maintained in the display region to ensure proper electrical insulation. This local differentiation resolves the contradiction between reliability and manufacturing precision
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 ensures a reliable detection of the dry etching end point and reduces the taper angle to 45 degrees or less, preventing wiring line shift and film breakage at the bending sections, thereby enhancing the manufacturing process and device reliability.
Implementation Method 1
the silicon oxide film as the material used for the inorganic insulating film, which makes it possible to reduce the taper angle than the taper angle of the silicon nitride film, overlaps the light emission of plasma due to oxygen in the resist
Data Source
AI summary
At a bending section of a frame region, an opening portion is formed, in at least one inorganic insulating film included in the TFT layer, through the at least one inorganic insulating film to expose an upper surface of a resin substrate, and a frame wiring line is provided on the resin substrate exposed through the opening portion, and among the at least one inorganic insulating film included in the TFT layer, an inorganic insulating film being in contact with the upper surface of the resin substrate is formed with a silicon oxynitride film.