Composite Oxide Semiconductor Structure for Stable Oxide TFT Switching
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Solution Overview
Problem
Transistors using oxide semiconductor films face challenges with high field-effect mobility leading to normally-on characteristics and adverse effects from oxygen vacancies, which affect electrical characteristics and reliability.
Innovation Solution
A composite oxide semiconductor is developed with a mixture of regions containing indium and oxygen, and zinc or tin, with specific atomic ratios and structures to enhance conductivity and reduce oxygen vacancies, improving field-effect mobility and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the field-effect mobility of a transistor is increased by using an oxide semiconductor film as a channel region, then the transistor performance is improved, but the transistor tends to exhibit normally-on characteristics
Solution Approach 1:
The patent applies local quality by creating distinct regions within the oxide semiconductor film with different compositions and properties. Specifically, it forms a first region with In-O clusters and a second region with Zn-O clusters, where each region has different carrier concentrations and conductivity characteristics. This spatial differentiation allows the channel to maintain high mobility in certain areas while controlling the overall off-state current to prevent normally-on behavior.
Solution Approach 2:
The patent employs composite materials by combining multiple oxide semiconductor regions with different metal compositions (In-O and Zn-O clusters) within a single channel film. This composite structure leverages the high mobility characteristics of In-O clusters while using Zn-O clusters to provide regions with lower carrier concentration, thereby achieving both high performance and reliable switching characteristics.
2Quantity of substance
If oxygen vacancies are formed in the oxide semiconductor film, then the carrier concentration increases, but the electrical characteristics change and reliability decreases
Solution Approach 1:
The patent applies local quality by creating distinct regions within the oxide semiconductor film with different compositions and properties. Specifically, it forms a first region with In-O clusters and a second region with Zn-O clusters, where each region has different carrier concentrations and conductivity characteristics. This spatial differentiation allows the channel to maintain high mobility in certain areas while controlling the overall off-state current to prevent normally-on behavior.
Solution Approach 2:
The patent converts the harmful effect of oxygen vacancies into a beneficial structure by intentionally forming In-O clusters and Zn-O clusters with controlled oxygen deficiency. These clusters, which would normally be considered defects, are strategically positioned and composed to provide high mobility pathways while their boundaries create natural barriers that prevent uncontrolled carrier generation. The harmful oxygen vacancies are thus transformed into structured features that enhance performance.
Data Source
AI summary
A novel composite oxide semiconductor which can be used in a transistor including an oxide semiconductor film is provided. In the composite oxide semiconductor, a first region and a second region are mixed. The first region includes a plurality of first clusters containing In and oxygen as main components. The second region includes a plurality of second clusters containing Zn and oxygen as main components. The plurality of first clusters have portions connected to each other. The plurality of second clusters have portions connected to each other.