Oxide Transistor Channel Stack for Mobility and Threshold Control
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Solution Overview
Problem
Conventional oxide transistors face limitations in improving charge mobility and achieving a desired threshold voltage range due to the use of a single layer of metal oxide as the active layer.
Innovation Solution
The oxide transistor is manufactured with a multi-layer structure comprising a first channel layer of indium-zinc oxide, a spacer of gallium oxide, and a second channel layer of indium-zinc oxide, formed through sequential gas supply processes to control the band gap and adjust charge mobility and threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer of metal oxide is used as the active layer, then the device structure is simple, but the charge mobility is limited and threshold voltage control is difficult
Solution Approach 1:
The active layer is divided into multiple channel layers (first channel layer and second channel layer) with different materials and charge mobility characteristics. This segmentation allows each layer to contribute differently to charge transport, thereby improving overall charge mobility while maintaining controllable threshold voltage through the combined effect of layers with varying properties.
Solution Approach 2:
The patent employs composite material structure by combining different metal oxide materials (e.g., In-Zn-O and Ga-O) in the active layer. This composite approach leverages the advantageous properties of each material to achieve enhanced charge mobility and improved threshold voltage control that cannot be obtained with a single material system.
2Reliability
If the thickness of the active layer is increased, then the transistor performance may improve, but the output voltage increases and stability deteriorates
Solution Approach 1:
Different channel layers are assigned different local qualities in terms of charge mobility and material composition. The first channel layer and second channel layer have distinct charge mobility characteristics, allowing the structure to achieve high overall performance while maintaining stable output voltage through the balanced contribution of layers with complementary properties.
3Ease of manufacture
If conventional single-layer metal oxide is used, then the manufacturing process is simple, but the threshold voltage range cannot be easily adjusted
Solution Approach 1:
The multi-layer structure provides dynamic adjustability of threshold voltage by varying the thickness, material composition, or stacking sequence of different channel layers. This allows flexible tuning of device characteristics to achieve desired threshold voltage ranges while maintaining a manufacturable process based on sequential deposition techniques.
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 structure enhances charge mobility to 50 cm²/V·s or more and allows stable operation without increasing output voltage, facilitating easy adjustment of the threshold voltage.
Implementation Method 1
a step of forming a first channel layer by supplying a gas containing indium (In) and zinc (Zn) and supplying a gas containing oxygen; a step of forming a spacer on the first channel layer by supplying a gas containing gallium (Ga) and supplying a gas containing oxygen; and a step of forming a second channel layer on the spacer by supplying a gas containing indium (In) and zinc (Zn) and supplying a gas containing oxygen
Data Source
AI summary
The present inventive concept provides a method of manufacturing an oxide transistor, the method comprising: a step of forming a first channel layer by supplying a gas containing indium (In) and zinc (Zn) and supplying a gas containing oxygen; a step of forming a spacer on the first channel layer by supplying a gas containing gallium (Ga) and supplying a gas containing oxygen; and a step of forming a second channel layer on the spacer by supplying a gas containing indium (In) and zinc (Zn) and supplying a gas containing oxygen, and an oxide transistor made by the method.