Electro-Optical Pixel Transistor Light Blocking for LDD Leakage
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Solution Overview
Problem
Existing electro-optical devices struggle to effectively suppress the entry of light sideways into the low-concentration impurity regions of semiconductor layers, leading to operation failures due to photocurrent, particularly in transistors with a lightly doped drain (LDD) structure.
Innovation Solution
The electro-optical device incorporates a first light blocker electrically coupled to the drain region and a second light blocker electrically coupled to the gate electrode, surrounding the boundary between the drain and channel regions, thereby enhancing light blocking and reducing photocurrent-induced failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first light blocking layer and light blocker are provided to cover the low-concentration impurity region from above the semiconductor layer, then operation failure resulting from photocurrent is suppressed, but entry of light sideways into the low-concentration impurity region cannot be sufficiently suppressed
Solution Approach 1:
The patent extends the light blocking function from a single horizontal layer to a three-dimensional structure by adding vertical light blockers at sidewalls. This multi-dimensional approach blocks light from both above (first light blocking layer) and sideways (light blockers at sidewalls), resolving the limitation of the conventional single-layer configuration.
Solution Approach 2:
The light blockers are positioned within the interlayer insulating layer structure, nested between different insulating layers. This nested configuration allows the light blockers to be integrated into the existing transistor structure while providing additional sideways light blocking capability without occupying excessive external space.
2Reliability
If the first light blocking layer and light blocker cover a wide range over the low-concentration impurity region, then photocurrent-induced operation failure is suppressed, but device complexity increases
Solution Approach 1:
Instead of providing uniform light blocking across the entire semiconductor layer, the patent applies light blocking structures selectively at critical locations: the first light blocking layer is positioned specifically over the low-concentration impurity region, and light blockers are placed only at the sidewalls of the source and drain regions where light entry would cause photocurrent. This localized approach maintains reliability while reducing overall complexity.
Solution Approach 2:
The light blocking function is segmented into multiple independent components: the first light blocking layer for top-down light blocking, and separate light blockers for sidewall light blocking. This segmentation allows each component to be optimized independently and simplifies the overall structure compared to a single monolithic light blocking system.
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 effectively suppresses light entry into the low-concentration drain regions, minimizing operation failures and improving display quality by reducing off-state leakage currents and black spot generation.
Implementation Method 1
a first light blocker electrically coupled to the drain region; and a second light blocker electrically coupled to the gate electrode, and the first light blocker and the second light blocker surround a boundary portion between the drain region and the channel region
Data Source
AI summary
An electro-optical device includes a substrate; a pixel electrode; a transistor including a gate electrode, and a semiconductor layer extending in a first direction and having a source region, a drain region, and a channel region, the transistor being disposed between the substrate and the pixel electrode; a first light blocker electrically coupled to the drain region; and a second light blocker electrically coupled to the gate electrode, and the first light blocker and the second light blocker surround a boundary portion between the drain region and the channel region in a plan view.