Zn-Based Oxide Transistor with Insulating Layer
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Solution Overview
Problem
The high cost and resource depletion concerns of indium (In) and gallium (Ga) in In-Ga-Zn-based oxide semiconductors, along with variability in threshold voltage, pose challenges for the development of efficient and cost-effective transistors for next-generation displays.
Innovation Solution
A transistor design that incorporates a Zn-based oxide layer with an insulating oxide semiconductor layer, where the oxide semiconductor layer has an amorphous structure with reduced conductivity, and is formed without using indium or gallium, by stacking the oxide semiconductor layer over the oxide layer with the oxide layer overlapping the source or drain electrode layers, using silicon oxide as the insulating oxide and forming the layers through sputtering methods with specific target compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If In-Ga-Zn-based oxide is used as the semiconductor layer, then high mobility and light-transmitting properties are achieved, but manufacturing cost increases due to expensive rare metals In and Ga
Solution Approach 1:
The invention extracts and removes the expensive rare metals In and Ga from the oxide semiconductor composition, retaining only Zn as the metal element. This extraction eliminates the cost issue while maintaining the functional performance of the transistor through optimized Zn-based oxide composition and structure.
Solution Approach 2:
The invention replaces expensive rare metals (In, Ga) with abundant and inexpensive Zn-based oxide materials. This substitution uses readily available, low-cost materials to achieve the same functional objectives, dramatically reducing manufacturing costs while maintaining device performance.
2Reliability
If In-Ga-Zn-based oxide is used as the semiconductor layer, then semiconductor characteristics are achieved, but resource depletion concerns arise due to scarcity of In and Ga
Solution Approach 1:
The invention extracts and eliminates the dependency on depleting rare metal resources (In and Ga) by formulating a semiconductor layer using only Zn-based oxide. This extraction from the material composition directly addresses resource depletion concerns while preserving essential semiconductor characteristics.
Solution Approach 2:
The invention changes the compositional parameters of the oxide semiconductor from In-Ga-Zn-based to purely Zn-based oxide. This parameter change in material composition shifts the resource base from scarce rare metals to abundant zinc, maintaining functionality while eliminating resource depletion issues.
3Ease of manufacture
If conventional oxide semiconductor structure is used, then manufacturing is simplified, but threshold voltage variability increases
Solution Approach 1:
The invention applies local quality by creating a multi-layer structure where an amorphous oxide semiconductor layer with specific properties is stacked on a crystalline ZnO layer. Each layer has distinct local characteristics that work together to reduce threshold voltage variability while maintaining manufacturing feasibility.
Solution Approach 2:
The invention uses composite material structure by stacking an amorphous oxide semiconductor layer containing insulating oxide on a crystalline ZnO layer. This composite structure combines the advantages of both amorphous and crystalline phases to achieve stable electrical characteristics and reduced threshold voltage variability.
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 approach reduces variation in threshold voltage and stabilizes electric characteristics, enabling the use of transistors in display devices with improved reliability and reduced manufacturing costs by eliminating the need for rare metals like indium and gallium.
Implementation Method 1
forming the layers through sputtering methods with specific target compositions
Data Source
AI summary
An object is to provide a transistor including an oxide layer which includes Zn and does not include a rare metal such as In or Ga. Another object is to reduce an off current and stabilize electric characteristics in the transistor including an oxide layer which includes Zn. A transistor including an oxide layer including Zn is formed by stacking an oxide semiconductor layer including insulating oxide over an oxide layer so that the oxide layer is in contact with a source electrode layer or a drain electrode layer with the oxide semiconductor layer including insulating oxide interposed therebetween, whereby variation in the threshold voltage of the transistor can be reduced and electric characteristics can be stabilized.