TFT Offset Structure Symmetrical Electrodes High Voltage
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Solution Overview
Problem
Conventional high-voltage thin film transistors (TFTs) with offset structures face a trade-off between low 'off' current and high 'on' current, where the high-resistance offset region reduces bias stress but decreases 'on' current efficiency.
Innovation Solution
The design includes an active region divided into multiple sub-regions with specific electrode connections and offset structures, ensuring symmetrical arrangements and overlapping configurations to maintain low 'off' current and high 'on' current levels by controlling electric field distribution across the channel regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-resistance offset region is employed to reduce bias stress and maintain low 'off' current, then the TFT becomes more resistant to high voltage, but the amount of 'on' current decreases
Solution Approach 1:
The active region is divided into multiple sub-regions (first active region, second active region, third active region) with different electrode configurations. Some sub-regions have overlapping source/drain electrodes with the gate electrode to maintain high on-current, while other sub-regions have offset structures to provide low off-current and bias stress resistance. This segmentation allows the TFT to simultaneously achieve both high reliability under high voltage and high on-current drive capability.
Solution Approach 2:
Different regions of the active area are assigned different functional qualities: regions requiring high current drive have overlapping electrode configurations, while regions requiring stress resistance have offset configurations. This local differentiation of electrode-gate overlap characteristics allows each region to optimize for its specific function, resolving the contradiction between on-current and off-current performance.
2Reliability
If an offset structure is used to prevent high electric fields in the channel layer, then the 'off' current is maintained at a low level, but the overall current flow capability is reduced
Solution Approach 1:
The channel is segmented into multiple active regions with different offset characteristics. By dividing the single channel into parallel channels with varying offset structures, the total current flow capability is maintained or enhanced while specific regions provide the necessary off-current control through offset configurations.
Solution Approach 2:
Multiple active regions with different electrode configurations are merged into a single TFT structure, combining the benefits of overlapping regions (high current) and offset regions (low off-current) into one integrated device that achieves both high productivity and reliable off-state control.
Data Source
AI summary
A thin film transistor (TFT) having an offset structure is disclosed. The TFT maintains a sufficiently low “off” current and a sufficiently high “on” current. The TFT includes an active region. The active region includes a gate electrode; an active layer that overlaps with the gate electrode; a gate insulating layer between the gate electrode and the active layer; and a source/drain electrode layer including source/drain electrodes that are electrically connected to the active region. Some of the source/drain electrodes overlap partially with the gate electrode. Other of the source/drain electrodes are offset from the gate electrode. The source/drain electrodes and the gate electrode are in a symmetrical arrangement.