Oxide Semiconductor Transistor Oxygen Vacancy Control
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Solution Overview
Problem
Transistors using oxide semiconductors face poor electrical characteristics due to hydrogen and oxygen vacancies, which shift the threshold voltage in the negative direction, leading to normally-on characteristics and manufacturing challenges, especially when high-temperature processing is required for miniaturization.
Innovation Solution
Forming insulating films, such as gate and sidewall insulating films, at temperatures below those that eliminate oxygen from the oxide semiconductor film, using plasma CVD methods with microwave plasma to prevent oxygen loss and generate dense films, and performing plasma treatment in oxygen or nitrogen atmospheres to fill vacancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment is applied to remove hydrogen from the oxide semiconductor film, then hydrogen is removed and electrical characteristics improve, but oxygen is eliminated and oxygen vacancies are generated causing threshold voltage shift
Solution Approach 1:
The patent applies preliminary action by performing plasma treatment in an oxygen atmosphere before high-temperature heat treatment to fill oxygen vacancies in advance. This preliminary oxygen supply ensures that when high-temperature treatment removes hydrogen, oxygen vacancies are immediately filled, preventing threshold voltage shift and maintaining electrical characteristics.
Solution Approach 2:
The patent uses plasma treatment in an oxygen or nitrogen atmosphere to create a controlled environment that prevents oxygen loss during subsequent high-temperature processing. The oxygen-rich plasma environment supplies oxygen to fill vacancies while the controlled atmosphere prevents excessive oxygen elimination from the oxide semiconductor film.
2Manufacturing precision
If high-temperature heat treatment is applied during insulating film formation to create thin and quality films, then insulating film quality improves and transistor miniaturization is enabled, but oxygen is eliminated from the oxide semiconductor film causing poor electrical characteristics
Solution Approach 1:
The patent performs plasma treatment in an oxygen atmosphere before forming insulating films at high temperature. This preliminary action fills oxygen vacancies in the oxide semiconductor film in advance, so that when high-temperature processing occurs during insulating film formation, the oxygen vacancies are already filled and cannot cause electrical characteristic degradation.
Solution Approach 2:
The patent changes the atmospheric parameters by introducing oxygen or nitrogen plasma before high-temperature insulating film formation. This parameter change (atmosphere composition) allows the oxide semiconductor film to maintain its oxygen content during subsequent high-temperature processing, enabling both thin quality insulating films and good electrical characteristics.
3Length of moving object
If the transistor is miniaturized by using thin insulating films, then device size is reduced and integration density increases, but manufacturing becomes more difficult due to sensitivity to oxygen vacancies
Solution Approach 1:
The patent applies preliminary plasma treatment in an oxygen atmosphere before miniaturization processing. This preliminary action fills oxygen vacancies and stabilizes the oxide semiconductor film, making it more robust against the stringent manufacturing variations that occur during miniaturization, thereby easing manufacturing difficulty.
Solution Approach 2:
The patent uses controlled oxygen or nitrogen plasma environments during the miniaturization process to protect the oxide semiconductor film from oxygen loss. This controlled atmosphere compensates for the increased sensitivity to oxygen vacancies that arises when transistors are miniaturized with thin insulating films.
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 inhibits the generation of oxygen vacancies, improves electrical characteristics by reducing contact resistance and enhancing field-effect mobility, and allows for the miniaturization of transistors with stable threshold voltages.
Implementation Method 1
plasma treatment in oxygen or nitrogen atmospheres to fill vacancies
Implementation Method 2
using plasma CVD methods with microwave plasma to prevent oxygen loss and generate dense films
Data Source
AI summary
A method for manufacturing a semiconductor device including an oxide semiconductor includes the steps of forming an oxide semiconductor film, forming a gate insulating film provided over the oxide semiconductor film, forming a gate electrode in contact with the gate insulating film, a sidewall insulating film in contact with the gate electrode, and forming a source electrode and a drain electrode in contact with the oxide semiconductor film. In the method, the gate insulating film and the sidewall insulating film are formed at a temperature at which oxygen contained in the oxide semiconductor film is inhibited from being eliminated, preferably at a temperature lower than a temperature at which oxygen contained in the oxide semiconductor film is eliminated.