Dual-Gate Transistor Light Shielding Against Photo-Degradation
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Solution Overview
Problem
Conventional liquid crystal display devices experience photo-degradation of transistors due to direct light irradiation, leading to significant changes in electrical properties and reliability issues.
Innovation Solution
The semiconductor device incorporates a light-shielding first gate electrode and second gate electrode, electrically connected through openings in the gate insulating films, which effectively block light from reaching the transistor channel, preventing photo-degradation by confining the channel with these electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the transistor channel is exposed to light for display operation, then the display function is enabled, but photo-degradation of the transistor occurs leading to electrical property changes and reliability issues
Solution Approach 1:
The gate electrode is divided into two separate gates (first gate and second gate) positioned on opposite sides of the channel. This segmentation allows each gate to independently control light shielding, creating a confined region where the channel is protected from direct light exposure while still enabling display operation through controlled light modulation.
Solution Approach 2:
The light-shielding gates are positioned and configured to preemptively block light from reaching the channel before photo-degradation can occur. The gates create a light-blocking configuration that prevents harmful light exposure in advance, counteracting the potential damage before it affects transistor reliability.
2Reliability
If light-shielding electrodes are added to protect the channel, then photo-degradation is suppressed, but device complexity increases
Solution Approach 1:
The first and second gates serve dual functions: they control the electrical operation of the transistor as gate electrodes and simultaneously function as light-shielding structures to protect the channel. This multi-functionality eliminates the need for separate light-blocking components, reducing overall device complexity while maintaining reliability.
Solution Approach 2:
The light-shielding function is merged with the gate electrode structure itself. Rather than adding separate light-blocking components, the invention combines the electrical control function and light shielding function into a single integrated gate system, simplifying the overall device architecture.
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 significantly suppresses photo-degradation of transistors, ensuring highly reliable semiconductor devices with minimal characteristic changes, even when light is directed parallel to the substrate surfaces.
Implementation Method 1
The second gate insulating film is located over the pair of terminals. The second gate electrode has a light-shielding property, is located over the second gate insulating film
Data Source
AI summary
A transistor includes a gate line, a first gate insulating film, a semiconductor film, a pair of terminals, a second gate insulating film, and a second gate electrode. A part of the gate line functions as a first gate electrode. The first gate insulating film is located over the first gate electrode. The semiconductor film is located over the first gate insulating film and overlaps the first gate electrode. The terminals are located over and electrically connected to the at least one semiconductor film. The second gate insulating film is located over the terminals. The second gate electrode has a light-transmitting property, is located over the second gate insulating film, overlaps the first gate electrode and the at least one semiconductor film, and is electrically connected to the first gate electrode through a first pair of openings formed in the first gate insulating film and the second gate insulating film.