Electro-Optical Device Circuit Board Relay Electrode Design
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Solution Overview
Problem
The existing lamination structures for electro-optical devices face challenges in maintaining the quality of dielectric films due to surface pollution and thickness deviations during the contact-hole formation process, leading to potential leakage currents and reduced reliability of storage capacitors.
Innovation Solution
A circuit board configuration that eliminates the need for forming contact holes through dielectric films by using an inter-bedded insulation film, allowing for precise control and preventing surface degradation, with a storage capacitor design that includes a fixed-electric-potential-side capacitor electrode, a dielectric film, and a pixel-electric-potential-side capacitor electrode, where the pixel electrode functions as a relay electrode to provide an electric connection between the transistor and the storage capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are formed through the dielectric film to electrically connect the upper capacitor electrode to the TFT, then electrical connection is achieved, but the surface of the dielectric film becomes polluted and its quality degrades
Solution Approach 1:
The patent divides the electrical connection path into two separate segments: (1) a first contact hole through the inter-bedded insulation film connecting the pixel electrode to the first relay electrode, and (2) a second contact hole through the inter-bedded insulation film connecting the first relay electrode to the TFT. This segmentation avoids the need to form contact holes through the dielectric film of the storage capacitor, thereby preserving dielectric film quality while achieving the required electrical connections.
Solution Approach 2:
The patent introduces a first relay electrode as an intermediary element between the pixel electrode and the TFT. This relay electrode serves as a mediator that receives electrical signals from the pixel electrode via the first contact hole and transmits them to the TFT via the second contact hole, eliminating the need for direct contact hole formation through the dielectric film.
2Ease of manufacture
If resist mask is applied and removed during contact-hole formation, then contact holes are created, but residual resist pollutes the dielectric film surface
Solution Approach 1:
The patent segments the contact hole formation process into two separate operations: forming the first contact hole through the inter-bedded insulation film, and forming the second contact hole through the inter-bedded insulation film. Since neither contact hole penetrates the dielectric film, the harmful resist application and removal processes are eliminated from the dielectric film surface, preventing pollution while maintaining manufacturability.
3Reliability
If contact hole formation treatment is performed on the dielectric film surface, then electrical connection is enabled, but the dielectric film thickness deviates from design specifications
Solution Approach 1:
The patent segments the electrical connection path to route connections through the inter-bedded insulation film rather than through the dielectric film. The first contact hole connects the pixel electrode to the first relay electrode through the insulation film, and the second contact hole connects the relay electrode to the TFT through the insulation film, preserving the dielectric film's original thickness and quality.
Solution Approach 2:
The patent changes the spatial dimension of the connection path by introducing a relay electrode at a different layer level. Instead of creating vertical connections through the dielectric film, the connection is established through horizontal and diagonal paths via the relay electrode, avoiding interference with dielectric film thickness control.
4Ease of manufacture
If the dielectric film surface is eroded during contact-hole formation, then contact holes are created, but the withstanding pressure of the dielectric film decreases
Solution Approach 1:
The patent segments the contact hole formation to occur exclusively in the inter-bedded insulation film, separating this manufacturing operation from the dielectric film. The first and second contact holes are both formed through the insulation film, which does not require the same level of surface integrity as the dielectric film, thereby preserving the dielectric film's withstanding pressure and structural strength.
Data Source
AI summary
An electro-optical device includes a pixel electrode, a transistor for driving the pixel electrode, and a storage capacitor for maintaining the voltage applied to the pixel electrode. The pixel electrode includes a first relay electrode formed in a layer above the pixel-electric-potential-side capacitor electrode of the storage capacitor with the interlayer insulation film sandwiched therebetween. The first relay electrode is electrically connected to the pixel-electric-potential-side capacitor electrode through the first contact hole.