Bent Gate Scanning Line Layout for Higher-Aperture Display Substrates
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Solution Overview
Problem
Top-gate self-aligned oxide thin film transistors in display panels require a large metal light-shielding layer, which reduces the aperture ratio and affects the display performance due to increased area occupation, especially in LCD panels.
Innovation Solution
The design incorporates a bent gate scanning line that intersects with the semiconductor layer, forming a channel and gate electrode, reducing the overall length of the thin film transistor and minimizing the need for a large light-shielding layer, thereby increasing the aperture ratio and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal light-shielding layer is added to protect the oxide thin film transistor from light, then the stability of device characteristics is improved, but the area occupied by the transistor increases and the aperture ratio decreases
Solution Approach 1:
The gate scanning line is merged with the gate electrode of the thin film transistor. The gate scanning line is extended to overlap with the semiconductor layer, forming the gate electrode directly, eliminating the need for a separate metal light-shielding layer while maintaining electrical connection and stability.
Solution Approach 2:
The gate scanning line serves dual functions: as a signal transmission line and as the gate electrode of the transistor. This multi-functionality reduces the number of separate components needed, particularly eliminating the dedicated light-shielding layer while maintaining protection through the overlapping structure.
2Object-affected harmful factors
If a separate metal light-shielding layer is designed, then the shielding effect on the semiconductor layer is improved, but the device structure becomes more complex
Solution Approach 1:
The gate scanning line and gate electrode are combined into a single continuous structure. The gate scanning line is extended beyond the semiconductor layer to form the gate electrode, merging the signal line function with the gate control function in one unified structure.
Solution Approach 2:
The gate scanning line performs multiple functions simultaneously: it transmits the scanning signal and serves as the gate electrode for controlling the transistor channel. This eliminates the need for separate light-shielding structures while maintaining all necessary functions.
3Area of stationary object
If the gate scanning line is extended to overlap with the semiconductor layer, then the area occupied by the transistor is reduced and aperture ratio is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The gate scanning line is designed to extend in advance beyond the semiconductor layer boundaries during the patterning process. This preliminary extension ensures that the overlapping region is already formed before subsequent processing steps, facilitating the formation of the gate electrode without requiring additional high-precision alignment steps.
Solution Approach 2:
The gate scanning line structure serves its own function as the gate electrode. By extending the gate scanning line to overlap with the semiconductor layer, the structure automatically forms the necessary gate electrode region without requiring separate fabrication steps or additional alignment procedures, reducing manufacturing complexity.
Data Source
AI summary
Provided are a display substrate and a display device. The display substrate includes: a base, gat scanning lines and data signal lines on the base and intersected with each other, and pixel units; each pixel unit has a pixel display area and a driving device area, a portion of the gate scanning line is bent towards the pixel display area to form a bent portion; each pixel unit includes thin film transistors in the driving device area, each thin film transistor includes a semiconductor layer; length directions of the bent portion and the semiconductor layer intersects, orthographic projections of the bent portion and the semiconductor layer on the base at least partially overlaps; a part of the semiconductor layer overlapping with the bent portion forms a channel, and a part of the bent portion overlapping with the semiconductor layer serves as a gate electrode of the thin film transistor.