Thin-Film Transistor Auxiliary Layer for Hump Effect Control

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Solution Overview

Problem

The hump effect in thin film transistors causes instability in performance due to early turn-on currents at the edge regions of the channel, affecting sub-threshold performance.

Innovation Solution

Incorporating an auxiliary layer that enhances the turn-on voltage of the edge region by adjusting the work function difference between the gate electrode and active layer materials, either through a conductive or semiconductor auxiliary layer, to synchronize turn-on currents across the edge and main regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the turn-on voltage of the edge region is not enhanced, then the manufacturing process is simple, but the hump effect occurs causing performance instability

Engineering Contradiction:

Improveperformance stabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

An auxiliary gate electrode is introduced as an intermediary component between the main gate electrode and the active layer. This auxiliary electrode specifically targets the edge region to enhance its turn-on voltage, thereby suppressing the hump effect without complicating the overall manufacturing process excessively.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The auxiliary gate electrode is positioned only over the edge region of the active layer, creating a localized electric field enhancement. This local quality approach allows selective control of the edge region turn-on characteristics without affecting the main region, resolving the performance instability while maintaining manufacturing simplicity.

Inventive Principle:

Principle #3Local quality

2Reliability

If the turn-on voltage of the edge region is enhanced, then the hump effect is alleviated, but the device structure becomes more complex

Engineering Contradiction:

Improveperformance stabilityVSAvoidgate electrode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The gate electrode system is segmented into a main gate electrode and an auxiliary gate electrode. The auxiliary electrode is divided into multiple segments positioned at different edge regions, allowing independent control and optimization of each edge region's turn-on voltage, thus alleviating the hump effect with controlled structural complexity.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the work function difference is adjusted to enhance edge region turn-on voltage, then simultaneous turn-on currents are achieved, but the material selection becomes more restrictive

Engineering Contradiction:

Improveturn-on synchronizationVSAvoidmaterial adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The work function parameter of the auxiliary gate electrode material is specifically adjusted to create an appropriate work function difference with the active layer. This parameter change enables enhanced turn-on voltage at the edge region, achieving simultaneous turn-on currents while maintaining reasonable material adaptability through controlled parameter optimization.

Inventive Principle:

Principle #35Parameter changes

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 hump effect is alleviated, stabilizing the thin film transistor performance by ensuring simultaneous turn-on currents in both edge and main regions, thereby improving overall transistor functionality.

Implementation Method 1

adjusting the work function difference between the gate electrode and active layer materials

Methodology Applied

Scientific EffectWork function difference:

Data Source

PatentEP3683846B1Thin film transistor and manufacturing method therefor, and electronic apparatus

Publication Date: 2025.10.01 BOE TECHNOLOGY GROUP CO LTD

Figure 1A~1C
Figure 2A~2C
Figure 3~4B

AI summary

A thin film transistor includes a substrate, and a gate electrode (202), a gate insulating layer (204), an active layer, a source electrode and a drain electrode which are on the substrate (201). The active layer includes a channel region (208) between the source electrode and the drain electrode and the channel region (208) includes an edge region (209) along a channel length direction and a main region (210) outside the edge region. The thin film transistor further includes an auxiliary layer (203), a projection of the auxiliary layer (203) on the substrate (201) is at least partially overlapped with a projection of the edge region (209) of the channel region (208) on the substrate (201), and the auxiliary layer (203) is configured to enhance a turn-on voltage of the edge region (209) of the channel region (208). The thin film transistor provides the auxiliary layer (203) to enhance the turn-on voltage of the edge region (209) of the channel region (208), so that a hump effect of the thin film transistor is alleviated and a performance of the thin film transistor is improved.