TFT Display Light Shield Connection to Prevent Back Gate Effect
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Solution Overview
Problem
In active matrix display devices, light leakage current through the semiconductor layer of thin-film transistors can decrease contrast and deteriorate display performance, and existing techniques for suppressing this issue, such as forming a light shielding layer, can cause back gate effects if not properly connected.
Innovation Solution
A display device is designed with a light shielding layer formed between the thin-film transistor and the insulating substrate, overlapping the semiconductor layer, and electrically connected to the gate electrode through a connection electrode, thereby fixing the potential of the light shielding layer and suppressing potential fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding layer is formed on the array substrate to suppress light leakage current, then light leakage current is reduced and contrast is improved, but a back gate effect is caused on the thin-film transistor
Solution Approach 1:
A connection electrode is introduced as an intermediary component to electrically connect the light shielding layer to the gate electrode. This mediator allows the light shielding layer to be electrically grounded through the gate electrode, preventing the back gate effect while maintaining its light shielding function. The connection electrode resolves the contradiction by providing a electrical pathway that eliminates the harmful potential difference between the light shielding layer and the semiconductor layer.
2Object-generated harmful factors
If the light shielding layer is electrically connected to the gate electrode to suppress the back gate effect, then the back gate effect is reduced, but additional connection electrodes and processes are required
Solution Approach 1:
The connection electrode is merged with existing gate electrode structures or conductive layers in the display device. By combining the connection function with existing structural elements, the patent avoids adding significant complexity to the device while still achieving the electrical connection necessary to suppress the back gate effect.
3Object-generated harmful factors
If the light shielding layer is electrically connected to the gate electrode to suppress the back gate effect, then the back gate effect is reduced, but additional film formation or exposure processes are required
Solution Approach 1:
The connection electrode is formed as part of the gate electrode structure during the existing manufacturing process sequence. By preparing the connection electrode in advance as part of the gate electrode formation process, the patent eliminates the need for separate additional film formation or exposure processes, thereby maintaining manufacturing efficiency while achieving the electrical connection to suppress the back gate effect.
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 leakage current and prevents the back gate effect, enhancing the contrast and overall performance of the display device while maintaining high definition and reducing costs associated with additional film formation or exposure processes.
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 through a connection electrode, thereby fixing the potential of the light shielding layer and suppressing potential fluctuations
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.