Thin-Film Transistor Gate Layout for Channel Length Stability
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Solution Overview
Problem
In thin film transistors with a top gate structure, the oxide semiconductor layer processing often results in an excessively conductive region, leading to a shorter channel length and a negative shift in threshold voltage, causing leakage current and increased power consumption in display panels.
Innovation Solution
A thin film transistor substrate design where the gate electrode has a convex shape with one side oriented towards the source or drain electrode, and the active layer includes active holes perpendicular to the source and drain electrodes, ensuring consistent channel length and reducing dopant ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the oxide semiconductor layer is processed using the gate electrode as a mask, then the channel region can be formed, but the conductive region is excessively penetrated causing the channel length to be reduced and threshold voltage to shift negatively
Solution Approach 1:
The gate electrode is designed with an asymmetric structure where one side is convexly disposed in the direction of the source or drain electrode. This asymmetric geometry creates a non-uniform spacing between the gate electrode and the active layer, which controls the penetration depth of the conductive region differently on each side, thereby maintaining the intended channel length and preventing threshold voltage shift
Solution Approach 2:
The convex side of the gate electrode creates a local geometric feature that modifies the doping or deposition process locally. By having different geometries at different locations of the gate electrode, the patent achieves different penetration depths in different regions, ensuring that the channel length is maintained while still forming the necessary conductive regions
2Productivity
If the channel length is reduced due to excessive penetration, then the transistor can be miniaturized, but leakage current increases and power consumption increases
Solution Approach 1:
The asymmetric gate electrode structure allows for precise control of the channel dimensions while maintaining adequate channel length. The convex side creates a protective geometry that prevents excessive penetration, ensuring that even in miniaturized devices, the channel length is sufficient to prevent leakage current and reduce power consumption
Data Source
AI summary
A thin film transistor substrate may include a substrate, an active layer disposed on the substrate, a gate electrode disposed on the active layer, a source electrode connected to one side of the active layer, and a drain electrode connected to another side of the active layer. The gate electrode may include a first side convexly disposed in a direction of any one of the source electrode and the drain electrode, the active layer may include a plurality of first active holes overlapping the first side, and the plurality of first active holes may be arranged in a direction perpendicular to a direction in which the source electrode and the drain electrode face each other. A display device using the thin film transistor substrate is also disclosed.