Oxide Semiconductor Transistor Oxygen Diffusion
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Solution Overview
Problem
Transistors using oxide semiconductors face issues with oxygen vacancies leading to poor electrical characteristics, reliability concerns, and a tendency to be normally-on due to localized states, which affect the threshold voltage and increase off-state current.
Innovation Solution
The introduction of a method where oxygen is added to specific oxide semiconductor films and diffused through heat treatment to reduce oxygen vacancies, employing a multi-layer structure with In-Ga-Zn oxide films and other metal oxide compositions to control energy levels and interface states, thereby improving electrical characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen is added to oxide semiconductor films through heat treatment, then oxygen vacancies are reduced and electrical characteristics improve, but the manufacturing process complexity increases
Solution Approach 1:
Oxygen is added to the first and third oxide semiconductor films during the manufacturing process before final assembly, so that oxygen vacancies are reduced in advance. This preliminary oxygen addition eliminates the need for subsequent complex oxygen replenishment treatments, resolving the contradiction between improving electrical characteristics and maintaining simple manufacturing processes.
2Reliability
If a multi-layer oxide semiconductor structure is used, then oxygen vacancy reduction and electrical performance improve, but the device structure becomes more complex
Solution Approach 1:
The invention applies different treatments to different layers of the oxide semiconductor structure. The first and third oxide semiconductor films receive oxygen addition treatment, while the second oxide semiconductor film does not. This localized differentiation optimizes oxygen vacancy reduction where needed without unnecessarily complicating the entire device structure, resolving the contradiction between improved electrical performance and structural simplicity.
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 enhances the electrical performance of oxide semiconductor transistors by reducing oxygen vacancies, stabilizing the threshold voltage, and minimizing off-state current, resulting in more reliable and efficient semiconductor devices with improved normally-off characteristics.
Implementation Method 1
the oxygen is diffused into the second oxide semiconductor film by heat treatment or the like, so that oxygen vacancies in the second oxide semiconductor film are reduced
Implementation Method 2
the oxygen is diffused into the second oxide semiconductor film by heat treatment or the like
Data Source
AI summary
A method for manufacturing a semiconductor device includes the steps of forming a first insulating film over a first gate electrode over a substrate while heated at a temperature higher than or equal to 450° C. and lower than the strain point of the substrate, forming a first oxide semiconductor film over the first insulating film, adding oxygen to the first oxide semiconductor film and then forming a second oxide semiconductor film over the first oxide semiconductor film, and performing heat treatment so that part of oxygen contained in the first oxide semiconductor film is transferred to the second oxide semiconductor film.