Oxide Semiconductor Diode Back Electrode for Narrow Frame LCD
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Solution Overview
Problem
Conventional liquid crystal displays using IPS mode have low transmittance due to insufficient driving of liquid crystal molecules above the pixel electrode, and oxide semiconductor-based diodes with shorter channel lengths suffer from leakage currents and etching damage, making it difficult to achieve high diode resistance and narrow frame arrays.
Innovation Solution
The array substrate incorporates a non-linear element with a light-shielding body, oxide semiconductor film, and back electrodes to provide high diode resistance and a reduced frame width, using a configuration where the back electrode overlaps the source electrode and separation portion on the oxide semiconductor film, connected through contact holes, and employing organic insulation films for planarization and improved voltage withstand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If oxide semiconductor-based diodes with shorter channel lengths are used, then the diode size is reduced, but leakage current increases and etching damage occurs, making it difficult to achieve high diode resistance
Solution Approach 1:
The patent introduces a back electrode positioned beneath the oxide semiconductor layer, creating a vertical electric field component that supplements the horizontal gate control. This three-dimensional electrode arrangement enhances carrier depletion efficiency without requiring increased channel length, thereby maintaining high diode resistance in compact structures
Solution Approach 2:
The patent applies different functional zones within the oxide semiconductor layer: the region under the gate electrode serves as the primary channel, while the region under the back electrode provides enhanced depletion and leakage current suppression. This localized functional differentiation allows short-channel diodes to achieve high resistance through spatially optimized electric field distribution
2Reliability
If the channel length is increased to provide high diode resistance, then the diode resistance improves, but the diode element increases in size and the frame region expands
Solution Approach 1:
The back electrode extends beneath the oxide semiconductor layer to provide vertical field enhancement, allowing the channel length to remain short while achieving high resistance through three-dimensional electric field control rather than relying on extended horizontal channel dimensions
Solution Approach 2:
The patent employs a composite electrode structure combining gate electrode and back electrode materials with different electrical properties, creating synergistic electric field effects that achieve high resistance in compact geometries without requiring frame region expansion
3Reliability
If conventional amorphous silicon diodes are used, then the diode resistance is acceptable, but the channel length must be 5 to 10 μm which increases device size
Solution Approach 1:
The patent changes the fundamental parameter of semiconductor material from amorphous silicon to oxide semiconductor, which inherently provides higher off-state resistance. This material parameter change enables short channel lengths (below 5 μm) to achieve the same or higher resistance levels that conventional materials require with much longer channels
Solution Approach 2:
The back electrode configuration adds a vertical control dimension that compensates for the short horizontal channel length, enabling oxide semiconductor diodes with sub-5-micron channels to achieve resistance levels comparable to or exceeding conventional 10-micron channels
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 enhances diode resistance, reduces the size of the non-linear element, and allows for the production of array substrates with narrow frames while maintaining high diode performance and manufacturing yield, compatible with FFS mode displays.
Implementation Method 1
Each diode included in the protection circuit is required to have a reasonably high resistance. The conventional diode made of amorphous silicon with a channel length of about 5 to 10 μm and a channel width of about 5 to 10 μm offers an acceptable diode resistance because an amorphous silicon film included in the diode has a high resistance.
Implementation Method 2
a light-shielding body disposed on the substrate, a first insulation film disposed so as to cover the light-shielding body
Data Source
AI summary
An array substrate according to the present invention includes a non-linear element. The non-linear element includes a first insulation film disposed so as to cover a light-shielding body, an oxide semiconductor film disposed on the first insulation film so as to overlap the light-shielding body in a plan view, a source electrode and a drain electrode that are disposed so as to be apart from each other with a separation portion therebetween on the oxide semiconductor film, a second insulation film disposed so as to cover the oxide semiconductor film, the source electrode, and the drain electrode, and a first back electrode disposed on a third insulation film and connected to a source wire through a first contact hole. The first back electrode is disposed so as to overlap the source electrode and part of the separation portion on the oxide semiconductor film in a plan view.