Oxide Semiconductor TFT Gate Stack for Stable Channel Oxidation
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Solution Overview
Problem
In liquid crystal display devices using oxide semiconductors, the oxidation of the active layer can be compromised due to holes or cracks in the aluminum oxide film, leading to display failures and reduced yields, as oxygen is dissipated from the gate insulating film.
Innovation Solution
A semiconductor device configuration with a thin film transistor (TFT) using an oxide semiconductor, where an aluminum oxide film is covered by a third insulating film to prevent oxygen loss and ensure adequate oxidation of the channel region, comprising a gate insulating film, an aluminum oxide film, an insulating film, and a gate electrode, with ion implantation to impart conductivity to the drain and source regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an aluminum oxide film is used to oxidize the oxide semiconductor active layer, then the oxidation of the channel region is improved, but the film may develop holes or cracks during manufacturing which causes oxygen to dissipate from the gate insulating film, leading to oxidation failure
Solution Approach 1:
The patent applies local quality by creating a multi-layer insulating film structure where different layers serve different local functions: the aluminum oxide film provides oxygen for oxidation, while the overlying insulating film provides protection and stability. This local differentiation of functions resolves the contradiction between achieving good oxidation quality and maintaining film stability.
Solution Approach 2:
The patent uses composite materials by combining aluminum oxide with other insulating materials in a multi-layer structure. This composite approach allows the system to benefit from both the oxygen-rich properties of aluminum oxide (for oxidation) and the stability/protection properties of the other insulating materials, thereby resolving the contradiction between oxidation effectiveness and film reliability.
2Device complexity
If the aluminum oxide film is made thinner to reduce manufacturing complexity, then the device complexity is reduced, but the film becomes more susceptible to holes and cracks, worsening the oxidation reliability
Solution Approach 1:
The patent applies segmentation by dividing the insulating film into multiple thinner layers rather than using a single thick layer. This segmentation allows each layer to be more easily manufactured without defects while collectively providing the necessary protection and oxidation functionality, resolving the contradiction between device complexity and oxidation reliability.
Solution Approach 2:
The patent uses beforehand cushioning by adding an insulating film layer that serves as a protective cushion over the aluminum oxide film. This protective layer prevents the aluminum oxide film from developing holes or cracks during manufacturing, thereby maintaining oxidation reliability without significantly increasing device complexity.
3Reliability
If ion implantation is used to impart conductivity to drain and source regions, then the electrical conductivity is improved, but the process adds manufacturing steps, increasing device complexity
Solution Approach 1:
The patent applies preliminary action by performing ion implantation early in the manufacturing process, before the aluminum oxide and insulating films are deposited. This timing allows the conductivity to be established in the semiconductor layer before subsequent layers are added, achieving the desired electrical properties without requiring additional complex processing steps later in the manufacturing sequence.
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 enhances the transistor properties of the oxide semiconductor TFT, reducing display failures and improving the yield of the display device by maintaining sufficient resistance in the channel region and ensuring stable oxidation.
Implementation Method 1
oxygen injected into a gate insulating film is dissipated
Implementation Method 2
the oxide semiconductor is oxidized using an aluminum oxide film
Implementation Method 3
performing ion implantation using the gate electrode as a mask to impart electrical conductivity to the drain region and the source region
Data Source
AI summary
There is provided a technique that enables a reduction in the display failure of a display device and the improvement of the yields of the display device in a display device that adopts a semiconductor device including a thin film transistor using an oxide semiconductor. A semiconductor device according to an embodiment includes a thin film transistor having an oxide semiconductor. The oxide semiconductor has a drain region, a source region, and a channel region provided between the drain region and the source region. The thin film transistor includes a gate insulating film provided on the channel region, an aluminum oxide film provided on the gate insulating film, an insulating film provided on the aluminum oxide film, and a gate electrode provided on the insulating film.