Oxide Semiconductor Transistor Stack With Oxygen-Rich Insulating Films
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Solution Overview
Problem
Oxide semiconductor films in transistors suffer from oxygen vacancies and impurities, leading to poor electrical characteristics, increased power consumption, and reliability issues, particularly in display devices, due to defects and impurities introduced during manufacturing.
Innovation Solution
A semiconductor device structure incorporating a multilayer film with an oxide semiconductor film and an oxide film containing In or Ga, where the second oxide insulating film has a higher oxygen content than stoichiometric, and is formed using specific deposition conditions to reduce oxygen vacancies and impurities, thereby improving electrical characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If oxide semiconductor films are used in transistors, then new semiconductor applications can be enabled, but oxygen vacancies and impurities cause poor electrical characteristics and reliability issues
Solution Approach 1:
The patent applies local quality by creating distinct regions with different oxygen concentrations within the oxide semiconductor structure. The gate insulating film contains oxygen to compensate for vacancies, while the oxide semiconductor film itself maintains semiconducting properties. This localized differentiation allows the structure to simultaneously achieve good electrical characteristics and high reliability.
Solution Approach 2:
The patent uses composite materials by combining oxide semiconductor films with gate insulating films that have different oxygen concentrations and compositions. This composite structure allows the oxide semiconductor to provide semiconducting functionality while the gate insulating film provides oxygen supply to reduce vacancies, thereby improving reliability without sacrificing adaptability.
2Productivity
If conventional manufacturing processes are used for oxide semiconductor films, then production can proceed, but defects and impurities are introduced leading to increased power consumption
Solution Approach 1:
The patent applies preliminary action by forming the gate insulating film with high oxygen concentration before forming the oxide semiconductor film. This preliminary oxygen-rich environment prevents the formation of oxygen vacancies during subsequent manufacturing steps, reducing defects and minimizing power consumption without affecting productivity.
Solution Approach 2:
The patent uses an inert atmosphere approach by maintaining oxygen-rich conditions during the formation of the gate insulating film, creating a protective environment that prevents impurity introduction and oxygen vacancy formation in the oxide semiconductor film, thereby reducing power consumption while maintaining efficient manufacturing.
3Ease of manufacture
If oxide semiconductor films are deposited without oxygen compensation, then manufacturing is simpler, but threshold voltage changes significantly under stress tests
Solution Approach 1:
The patent uses an intermediary approach by introducing the gate insulating film as a mediator between the manufacturing process and the oxide semiconductor film. This intermediary layer provides oxygen to compensate for vacancies without complicating the manufacturing process, thereby maintaining ease of manufacture while achieving high threshold voltage stability under stress conditions.
4Ease of manufacture
If oxygen vacancies are present in oxide semiconductor films, then film formation is easier, but electrical characteristics deteriorate and off-state current increases
Solution Approach 1:
The patent applies the blessing in disguise principle by converting the potential harm of oxygen vacancies into a benefit. The gate insulating film is intentionally designed with high oxygen concentration, which compensates for oxygen vacancies in the oxide semiconductor film. This converts what would be a defect into a mechanism for improving electrical characteristics and reducing off-state current.
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
The solution effectively reduces defects and impurities, leading to stable electrical characteristics, low off-state current, and reduced power consumption, with minimal change in threshold voltage under stress tests, enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
a second oxide insulating film which contains more oxygen than that in the stoichiometric composition... the second oxide insulating film is formed over the first oxide insulating film
Data Source
AI summary
To reduce defects in an oxide semiconductor film in a semiconductor device. To improve the electrical characteristics and the reliability of a semiconductor device including an oxide semiconductor film. In a semiconductor device including a transistor including a gate electrode formed over a substrate, a gate insulating film covering the gate electrode, a multilayer film overlapping with the gate electrode with the gate insulating film provided therebetween, and a pair of electrodes in contact with the multilayer film, a first oxide insulating film covering the transistor, and a second oxide insulating film formed over the first oxide insulating film, the multilayer film includes an oxide semiconductor film and an oxide film containing In or Ga, the first oxide insulating film is an oxide insulating film through which oxygen is permeated, and the second oxide insulating film is an oxide insulating film containing more oxygen than that in the stoichiometric composition.