Oxide TFT Gate Insulation Structure for Leak Current Suppression
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Solution Overview
Problem
In oxide semiconductor TFTs, the reduction of channel resistance leads to increased leak current due to oxygen extraction by the metal gate electrode, which reduces the oxygen supply from oxygen-rich SiO films, causing instability in the oxide semiconductor.
Innovation Solution
A two-layer aluminum oxide film structure is introduced between the oxide semiconductor film and the gate electrode, with a higher oxygen concentration in the first aluminum oxide film and a lower concentration in the second film, to prevent oxygen extraction and maintain oxygen supply to the oxide semiconductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal gate electrode is formed directly above the oxide semiconductor film via an insulating film, then the adhesive strength between the gate electrode and resist is improved, but oxygen is extracted from the oxide semiconductor through the insulating film, causing leak current to increase
Solution Approach 1:
An aluminum oxide film is introduced as an intermediary layer between the metal gate electrode and the oxide semiconductor film. This intermediary layer prevents direct oxygen extraction from the oxide semiconductor by the metal gate electrode, while still allowing the gate electrode to function properly. The aluminum oxide film acts as a barrier that mediates the interaction between the gate electrode and the semiconductor, blocking the harmful oxygen extraction pathway.
Solution Approach 2:
The aluminum oxide film is formed on the surface of the gate electrode before the gate electrode is positioned above the oxide semiconductor film. This preliminary formation of the aluminum oxide layer ensures that the oxygen barrier is in place before any oxygen extraction can occur, preventing the degradation of the oxide semiconductor's oxygen content and maintaining low leak current from the beginning of device operation.
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 leak current in TFTs by maintaining oxygen levels in the oxide semiconductor, ensuring stable transistor performance.
Implementation Method 1
an oxygen concentration in the first aluminum oxide film is bigger than an oxygen concentration in the second aluminum oxide film
Data Source
AI summary
A display device including a substrate having thin film transistors (TFT) comprising: the TFT including an oxide semiconductor film, a gate electrode and an insulating film formed between the oxide semiconductor film and the gate electrode, wherein a first aluminum oxide film and a second aluminum oxide film, which is formed on the first aluminum oxide film, are formed between the insulating film and the gate electrode, an oxygen concentration in the first aluminum oxide film is bigger than an oxygen concentration in the second aluminum oxide film.