TFT Display Light Shielding Layout to Suppress Back Gate Effects
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Solution Overview
Problem
Active matrix display devices face performance deterioration due to light leakage current, which can be exacerbated by the back gate effect caused by floating light shielding layers, leading to decreased contrast and image quality.
Innovation Solution
A display device design that includes a light shielding layer electrically connected to the gate electrode through a connection electrode, effectively suppressing the back gate effect and light leakage current by ensuring the potential of the light shielding layer is fixed to that of the gate electrode, thereby maintaining high definition performance without additional costly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a light shielding layer is formed on the array substrate to suppress light leakage current, then light leakage current is reduced, but the floating light shielding layer causes a back gate effect on the thin-film transistor
Solution Approach 1:
A connection electrode is introduced as an intermediary component between the light shielding layer and the gate electrode. This connection electrode electrically connects the floating light shielding layer to the gate electrode, thereby eliminating the back gate effect while preserving the light shielding function. The intermediary connection electrode resolves the contradiction by providing a conductive path that stabilizes the potential of the light shielding layer.
Solution Approach 2:
The light shielding layer is electrically connected to the gate electrode through the connection electrode, merging their electrical potentials. This combining of the light shielding layer with the gate electrode structure eliminates the floating potential issue that causes the back gate effect, while maintaining the light shielding function against the semiconductor layer.
2Reliability
If the light shielding layer is electrically connected to the gate electrode through a connection electrode, then the back gate effect is suppressed, but the device structure becomes more complex
Solution Approach 1:
The connection electrode serves multiple functions: it electrically connects the light shielding layer to the gate electrode to suppress the back gate effect, and it is integrated into the existing thin-film transistor structure. This multi-functional design eliminates the need for separate structures, thereby reducing overall device complexity while achieving the desired electrical connection.
Solution Approach 2:
The connection electrode is merged with the gate electrode structure, forming an integrated conductive path. This merging approach combines the light shielding function and the electrical connection function into a unified structure, avoiding the need for separate independent components and thereby minimizing structural complexity.
3Reliability
If additional processes are used to electrically connect the light shielding layer, then the back gate effect is suppressed, but manufacturing cost increases
Solution Approach 1:
The connection electrode is formed using the same thin-film deposition and patterning processes that are already employed for manufacturing the gate electrode and other TFT components. By merging the connection electrode fabrication into the existing manufacturing workflow, no additional costly processes are required, and the electrical connection is achieved through standard manufacturing techniques.
Solution Approach 2:
The existing thin-film deposition and patterning equipment and processes are used to form the connection electrode, giving these manufacturing processes multiple functions: forming the gate electrode, forming the light shielding layer, and forming the connection electrode. This multi-functional use of existing manufacturing capabilities avoids the need for additional specialized processes, thereby controlling manufacturing costs.
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
The solution effectively suppresses light leakage current and back gate effects, enhancing the contrast and overall performance of the display device while being cost-effective by integrating the electrical connection of the light shielding layer within the existing manufacturing process.
Implementation Method 1
a light shielding layer formed between the thin-film transistor and the insulating substrate to at least partly overlap the semiconductor layer
Implementation Method 2
the light shielding layer electrically connected to the gate electrode
Data Source
AI summary
According to one embodiment, a semiconductor device includes an insulating substrate, a first metal layer on the insulating substrate, a first insulating layer on the insulating substrate and the first metal layer, a semiconductor layer on the first insulating layer, a second insulating layer on the semiconductor layer and the first insulating layer, a second metal layer on the second insulating layer, and a first electrode and a second electrode which are electrically connected to the semiconductor layer. The first metal layer overlaps the second metal layer. A third metal layer contacts a top surface of the second metal layer and a top surface of the first metal layer.