Display ESD Diode Layout With Back-Gate Light Shielding
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Solution Overview
Problem
In liquid crystal and organic EL display devices, the electrostatic protection circuit must maintain high sensitivity while occupying a reduced area, posing a dilemma as reducing its size lowers sensitivity, and existing configurations struggle to achieve this balance.
Innovation Solution
The configuration involves connecting two diodes in series with a third connection wire, where the first and second diodes have overlapping light shielding films that extend beyond their semiconductor layers, allowing for increased channel width and capacitive coupling with a conductive light shielding film acting as a back gate, enhancing current flow without increasing the diode dimension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area occupied by the electrostatic protection circuit is reduced, then the frame region size is reduced and display region can be made larger, but the sensitivity of the electrostatic protection circuit is lowered
Solution Approach 1:
The light shielding film is extended in the planar dimension beyond the semiconductor layer boundaries, creating an overlapping structure that adds functional area without increasing the vertical profile or requiring additional space. This dimensional extension allows the electrostatic protection circuit to achieve both compactness and high sensitivity simultaneously.
Solution Approach 2:
The light shielding film serves dual functions: it shields light from reaching the semiconductor layer while simultaneously acting as a conductive back gate through capacitive coupling. This merging of light shielding and electrostatic protection functions into a single structural element maximizes the utility of the limited frame region space.
2Area of moving object
If the diode dimension is reduced, then the area occupation is reduced, but the sensitivity of the electrostatic protection circuit is compromised
Solution Approach 1:
By extending the light shielding film in the planar dimension to overlap with the connection wire, the effective functional area is increased without proportionally increasing the physical diode footprint. This dimensional strategy maintains sensitivity while reducing overall area occupation.
Solution Approach 2:
The light shielding film performs multiple functions including light blocking, capacitive coupling for electrostatic protection, and gate control. This multi-functionality allows a single structure to deliver enhanced performance within a reduced area footprint.
3Reliability
If the light shielding film area is increased to enhance capacitive coupling, then the electrostatic protection sensitivity is improved, but the area occupation increases
Solution Approach 1:
The light shielding film is strategically extended in the planar dimension to overlap with the connection wire positioned between the diodes. This targeted extension in a specific dimension maximizes capacitive coupling for electrostatic protection while minimizing overall area increase, as the extension is confined to the inter-diode region rather than uniformly expanding the structure.
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 maintains high sensitivity of the electrostatic protection circuit even when the diode dimension is reduced, allowing for a smaller area occupation without compromising protection functionality.
Implementation Method 1
the first light shielding film is formed, as viewed in a plan view, to extend to an overlapping position with the third connection wire and is formed in an overlapping relation with the semiconductor layer to possess a wider area than the semiconductor layer
Data Source
AI summary
To make the dimension of an electrostatic protection circuit small with the same maintained high in sensitivity. The electrostatic protection circuit is of the configuration that a first diode and a second diode are connected in series, wherein a semiconductor layer owned by each diode is configured to be sandwiched between a gate electrode and a conductive light shielding film. The light shielding film is formed to overlap with the semiconductor layer and has a wider area than the semiconductor layer. This results in having a gate covering the semiconductor layer from an upper side and a back gate covering the semiconductor layer from a lower side, so that the sensitivity can be maintained high irrespective of decreasing the electrostatic protection circuit in dimension.