Holding Capacitance Element Stacked Structure for Display Devices
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Solution Overview
Problem
In active-drive liquid crystal and organic electroluminescence display devices, parasitic capacitance in the crossing region of gate and source/drain electrodes leads to variations in signal voltage, degrading image quality and increasing the probability of short circuits, which reduces production yield.
Innovation Solution
A holding capacitance element is formed with a stacked structure on a substrate, using a first conductive film, a semiconductor layer with an oxide semiconductor, and a second conductive film, with an insulating film sandwiched between them, to maintain consistent capacitance and reduce voltage-dependent variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If parasitic capacitance is reduced in the crossing region of gate electrode and source/drain electrode, then signal voltage variation is suppressed and image quality is improved, but holding capacitance element capacitance may become insufficient
Solution Approach 1:
The holding capacitance element is divided into a stacked structure with multiple layers (first conductive film, first semiconductor layer, insulating film, second conductive film) to achieve the desired capacitance value while maintaining compact dimensions. This segmentation allows precise control of capacitance through layer thickness and material selection without increasing overall footprint.
Solution Approach 2:
The holding capacitance element transitions from a planar structure to a stacked three-dimensional structure. By utilizing the vertical dimension with multiple alternating conductive and insulating/semiconductor layers, the capacitance is increased without expanding the horizontal wiring occupancy, thus preventing short circuits while maintaining sufficient holding capacitance.
2Reliability
If holding capacitance element capacitance is increased to compensate for parasitic capacitance, then signal voltage stability is improved, but wiring occupancy increases and short circuit probability increases
Solution Approach 1:
The holding capacitance element utilizes a stacked vertical structure with alternating conductive and insulating layers, transforming the capacitance generation from a horizontal expansion to a vertical stacking approach. This reduces wiring occupancy and short circuit probability while achieving the required capacitance value for signal voltage stability.
Solution Approach 2:
The holding capacitance element employs composite layered structure combining conductive films (such as ITO, IZO, IGZO) with insulating films and semiconductor layers. This composite structure achieves high capacitance density in a compact footprint by optimizing the dielectric properties of each layer while maintaining electrical connectivity.
3Stability of the object's composition
If stacked structure with oxide semiconductor is used in holding capacitance element, then capacitance variations with applied voltage are suppressed, but manufacturing process complexity increases
Solution Approach 1:
The holding capacitance element utilizes oxide semiconductor materials (such as ITO, IZO, IGZO) with specific compositional parameters that provide stable dielectric properties across different applied voltages. By controlling the oxide composition ratios and layer thicknesses, the capacitance stability is achieved while maintaining compatibility with existing thin-film deposition processes.
Solution Approach 2:
The stacked structure combines conductive oxide films with insulating films and semiconductor layers, creating a composite material system where each layer contributes specific properties. The oxide semiconductor layers provide stable electrical characteristics and good interface properties, enabling capacitance stability while using established sputtering and deposition techniques for manufacturing.
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 suppresses capacitance variations, maintaining desired capacitance and improving image quality, reducing defects in the display panel and enhancing production yield by minimizing wiring occupancy.
Implementation Method 1
a holding capacitance element holding electric charge corresponding to a video signal
Data Source
AI summary
A display device includes a substrate, a display element, a transistor as a drive element of the display element, and a holding capacitance element holding electric charge corresponding to a video signal, and including a first conductive film, a first semiconductor layer including an oxide semiconductor, an insulating film, and a second conductive film in order of closeness to the substrate. The display element, the transistor, and the holding capacitance element are provided on the substrate.