Gate Relay Electrode Opening for Off-Leak Current Reduction
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Solution Overview
Problem
In electro-optical devices like liquid crystal display devices, the close proximity of light shielding films to transistors can lead to increased off-leak current, causing display quality issues such as black spots due to the light shielding film overlapping regions other than the channel region of the transistor.
Innovation Solution
The introduction of a gate relay electrode with an opening portion that overlaps the gap between the gate electrode and the light shielding layer, reducing the influence of the gate relay electrode's potential on the drain region side LDD region and blocking light incidence through strategically positioned contact holes, thereby minimizing off-leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light shielding film is placed closer to the semiconductor layer to improve light-shielding properties, then light-shielding effectiveness is improved, but off-leak current increases due to overlapping with regions other than the channel region
Solution Approach 1:
The light shielding film is divided into a first light shielding film and a second light shielding film at different positions. The first light shielding film is positioned closer to the semiconductor layer to provide strong light shielding, while the second light shielding film is positioned farther away to block light from reaching regions outside the channel region, thereby preventing off-leak current while maintaining light-shielding effectiveness.
Solution Approach 2:
A gate relay electrode is introduced as an intermediary component between the gate electrode and the light shielding film. This gate relay electrode includes an opening portion that prevents light from incident on regions other than the channel region, thereby blocking the path that would cause off-leak current while allowing the light shielding film to function effectively.
2Area of stationary object
If the light shielding film overlaps the entire region of the transistor to ensure comprehensive light shielding, then light-shielding coverage is improved, but off-leak current increases due to influence on regions other than the channel region
Solution Approach 1:
Different regions of the light shielding structure are assigned different functions: the first light shielding film provides strong shielding where needed, the second light shielding film blocks light from reaching non-channel regions, and the gate relay electrode with its opening portion selectively allows light to reach only the channel region. This localized functional differentiation prevents off-leak current while maintaining comprehensive light shielding coverage.
3Object-affected harmful factors
If the gate relay electrode is positioned close to the light shielding layer to block light effectively, then light-blocking effectiveness is improved, but the potential influence on the drain region side LDD region increases
Solution Approach 1:
The gate relay electrode is segmented with an opening portion that creates a gap between the electrode and the light shielding layer. This segmentation allows light to be blocked effectively in most regions while preventing the electrode's potential from influencing the drain region side LDD region, as the opening interrupts the capacitive coupling path.
Data Source
AI summary
An electro-optical device includes a substrate, a pixel electrode, a transistor disposed in a layer between the pixel electrode and the substrate, a gate relay electrode disposed in a layer between the pixel electrode and the transistor, and a light blocking shield layer disposed in a layer between the gate relay electrode and the transistor. The gate relay electrode is electrically coupled to a gate electrode of the transistor, and includes an opening portion at a position overlapping, at least in plan view, a gap formed between the gate electrode and the light blocking shield layer in plan view.