Array Substrate for Organic Electroluminescent Device
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Solution Overview
Problem
The existing array substrates for organic electroluminescent devices require a large number of mask processes, leading to high production costs and inefficiencies, and the storage capacitors in these devices have insufficient capacity due to the trend towards high resolution, which reduces the aperture ratio and image display stability.
Innovation Solution
A method of fabricating an array substrate that reduces the number of mask processes by forming a semiconductor layer and storage electrodes in a pixel region defined by gate and data lines, using impurity-doping to create ohmic contact layers, and forming multiple-layered gate electrodes and storage capacitors, resulting in increased storage capacity with fewer mask steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of mask processes is reduced to lower production costs and improve efficiency, then manufacturing complexity decreases, but it becomes difficult to form precise semiconductor layers and storage electrodes with proper patterns
Solution Approach 1:
The patent combines multiple mask processes into fewer steps by using a dual-function photoresist layer that serves both as a pattern mask for semiconductor layer formation and as an etch mask for storage electrode formation. This merging of functions reduces the total number of mask processes while maintaining the precision needed for forming both the semiconductor layer and storage electrodes with proper patterns.
Solution Approach 2:
The photoresist layer is designed to perform multiple functions: it acts as a pattern definition mask for the semiconductor layer, serves as an etch mask for forming storage electrodes, and provides alignment references for subsequent processing steps. This multi-functionality allows the patent to reduce mask process steps without sacrificing manufacturing precision.
2Reliability
If the area of storage capacitor is increased to secure sufficient storage capacity, then storage capacity improves, but the aperture ratio of the pixel region decreases
Solution Approach 1:
The patent transitions from planar storage capacitor structures to three-dimensional overlapping structures. By forming storage electrodes that extend in multiple layers and utilize vertical space through the inter-layered insulating film, the storage capacitor achieves increased capacity without occupying more horizontal area, thereby maintaining the aperture ratio while improving storage capacity.
Solution Approach 2:
The storage capacitor structure is designed with nested overlapping regions where storage electrodes are positioned above and below the semiconductor layer, separated by insulating films. This nested arrangement allows the storage capacitor to be embedded within the vertical structure of the pixel, maximizing space utilization and achieving high storage capacity within the limited pixel area.
3Reliability
If double overlap configuration is used to increase storage capacity per unit area, then storage capacity improves, but the area available for other pixel components decreases
Solution Approach 1:
The patent applies the overlap configuration selectively in specific local regions rather than uniformly across the entire pixel. The storage electrodes are positioned to overlap with the semiconductor layer only in the storage region, while the element region maintains sufficient area for transistor operations. This localized application of overlapping structures increases storage capacity per unit area without compromising the area needed for other pixel components.
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 reduces production costs and time by minimizing mask processes and enhances storage capacity per unit area, improving image display stability and aperture ratio through the use of overlapping storage capacitors.
Implementation Method 1
performing an impurity-doping to make a portion of the semiconductor layer not covered by the gate electrode into an ohmic contact layer and make the semiconductor pattern into a second storage electrode
Data Source
AI summary
A method of fabricating an array substrate for an organic electroluminescent device includes forming a semiconductor layer of polysilicon in an element region, and a semiconductor pattern of polysilicon in a storage region on a substrate; forming a multiple-layered gate electrode corresponding to a center portion of the semiconductor layer and a first storage electrode corresponding to the semiconductor pattern; performing an impurity-doping to make a portion of the semiconductor layer not covered by the gate electrode into an ohmic contact layer and make the semiconductor pattern into a second storage electrode; forming source and drain electrodes and a third storage electrode corresponding to the first storage electrode; forming a first electrode contacting the drain electrode and a fourth storage electrode corresponding to the third storage electrode.