Stacked Transparent Capacitor Layout for Small-Pixel Displays
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Solution Overview
Problem
The reduction in pixel size of display devices limits the area for capacitive elements, leading to unstable charge holding and display operations due to insufficient capacitive element size, which affects the performance of pixel circuits using oxide semiconductor transistors.
Innovation Solution
The design includes a configuration with multiple transparent conductive layers and capacitive elements stacked above the selection transistor, ensuring efficient capacitive element formation in a small area, and direct contact between the oxide semiconductor layer and the connecting electrode to maintain electrical conductivity without additional metal layers, thereby stabilizing display operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to enhance resolution, then the resolution is improved, but the area for capacitive elements is limited leading to insufficient capacitance and unstable charge holding
Solution Approach 1:
The patent transitions from a planar capacitive element design to a three-dimensional stacked structure. Multiple transparent conductive layers (first, second, and third transparent conductive layers) are arranged in vertical stacks above the transistor, creating capacitive elements that utilize the third dimension. This dimensional change allows sufficient capacitance to be achieved within the limited pixel area, resolving the contradiction between reduced pixel size and adequate capacitive element area.
Solution Approach 2:
The patent implements a nested structure where multiple transparent conductive layers are stacked and isolated from each other, with each layer nested within the vertical space above the transistor. The first transparent conductive layer is positioned above the transistor, the second transparent conductive layer is isolated and facing the first layer, and the third transparent conductive layer is isolated and connected to the first layer. This nesting arrangement maximizes the use of vertical space to achieve sufficient capacitance in a miniaturized pixel.
2Reliability
If additional metal layers are inserted between the oxide semiconductor layer and connecting electrode, then electrical conductivity is improved, but the aperture ratio is reduced and light transmittance deteriorates
Solution Approach 1:
The patent changes the material parameter of the connecting electrode from traditional metal to transparent conductive material. The third transparent conductive layer serves as the connecting electrode that directly contacts the oxide semiconductor layer, eliminating the need for additional metal layers. This parameter change maintains electrical conductivity while preserving light transmittance, as transparent conductive materials allow light to pass through while providing necessary electrical connection.
Solution Approach 2:
The patent extracts and removes the additional metal layers from the structure. By using the transparent conductive layers directly as connecting electrodes, the invention eliminates the harmful metal layers that would block light. This extraction of unnecessary components resolves the contradiction by maintaining electrical functionality without the light-blocking side effect.
Data Source
AI summary
A display device includes: a first transistor provided with an oxide semiconductor layer, a first gate electrode facing the oxide semiconductor layer and a first gate insulating layer between the oxide semiconductor layer and the first gate electrode; a first transparent conductive layer above the first transistor; a second transparent conductive layer above the first transparent conductive layer, the second transparent conductive layer being isolated from the first transparent conductive layer and facing the first transparent conductive layer; and a third transparent conductive layer above the second transparent conductive layer, the third transparent conductive layer being isolated from the second transparent conductive layer, being connected to the first transparent conductive layer and facing the second transparent conductive layer.