Display Panel Contact Electrode Coverage in High-Aspect-Ratio Holes
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Solution Overview
Problem
As display modules increase in size and resolution, the integration of signal lines and connecting electrodes increases, leading to challenges in the reliability of pixel drive circuits, particularly in forming connecting electrodes with suitable aspect ratios and step coverages for transistors.
Innovation Solution
A display panel design featuring a base layer, circuit layer with transistors, and insulating layers with defined contact holes for connecting electrodes, along with a sputtering device for forming thin metal films, ensuring an aspect ratio of 0.8 or more and a step coverage of 20% or more for improved connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size and resolution of display modules are increased, then the display quality is improved, but the integration of signal lines and connecting electrodes increases leading to reliability issues
Solution Approach 1:
The connecting electrode is divided into multiple segments (first connecting electrode, second connecting electrode, third connecting electrode) that are formed at different stages. This segmentation allows each electrode segment to be optimized independently for its specific function and location, improving overall reliability while accommodating higher resolution requirements
Solution Approach 2:
The first connecting electrode is formed in advance during the transistor formation stage, before the insulating layer is completely deposited. This preliminary action ensures proper electrical connection is established early in the process, preventing reliability issues that would arise from attempting to form connections after all layers are in place
2Reliability
If the aspect ratio of contact holes is increased to 0.8 or more, then the connectivity between transistors and connecting electrodes is improved, but the manufacturing complexity increases
Solution Approach 1:
The contact hole structure transitions from a simple vertical hole to a multi-dimensional structure with lateral surface portions that extend along the insulating layer. This dimensional change allows the connecting electrode to wrap around and make contact with transistor regions that would be inaccessible in a simple vertical contact hole, achieving better connectivity while managing the complexity through systematic design
3Reliability
If the step coverage of connecting electrodes is increased to 20% or more, then the electrical connection reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The connecting electrode formation process is made dynamic by forming different electrode segments at different stages of the manufacturing process. The first connecting electrode is formed during transistor fabrication, while subsequent electrodes are formed after insulating layer deposition. This dynamic, staged approach allows each electrode segment to be optimized for its specific manufacturing context, achieving 20% or more step coverage while managing precision requirements through process sequencing rather than demanding uniform precision across all stages
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
Enhances the reliability and connectivity of pixel drive circuits by maintaining optimal aspect ratios and step coverages, improving the integration and performance of display panels.
Implementation Method 1
a sputtering device for forming a thin metal film on a target substrate
Implementation Method 2
a sputtering device for forming a thin metal film on a target substrate having a contact hole defined therein
Data Source
AI summary
Disclosed is a display panel which includes a base layer, a circuit layer on the base layer, and a light emitting element on the circuit layer. The circuit layer includes a transistor, an insulating layer having a contact hole defined therein to expose a portion of the transistor, and a connecting electrode electrically connected with the transistor through the contact hole. An aspect ratio of the contact hole defined as a ratio of a depth of the contact hole to a width of the contact hole is 0.8 or more. The connecting electrode includes a lateral surface portion and an upper surface portion, and a step coverage defined as a ratio of a thickness of the lateral surface portion to a thickness of the upper surface portion is 20% or more. An electronic device including the display panel is also disclosed.