Oxide Semiconductor Transistor with Oxygen Release Insulator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transistors using oxide semiconductors face issues with hydrogen contamination and oxygen vacancies, leading to adverse effects on electric characteristics, particularly in the form of threshold voltage shifts and reduced mobility.
Innovation Solution
A semiconductor device structure and manufacturing method involving an oxide semiconductor film with a first oxide insulating film that releases oxygen and a second oxide insulating film that prevents oxygen diffusion, where the end portion of the oxide semiconductor film is positioned over the second insulating film to reduce oxygen vacancies and hydrogen contamination, enhancing electric characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrogen is present in the oxide semiconductor, then carrier concentration increases, but threshold voltage shifts and electric characteristics deteriorate
Solution Approach 1:
The patent removes hydrogen from the oxide semiconductor film by performing heat treatment in an oxygen atmosphere, extracting the harmful hydrogen impurities that cause threshold voltage shifts while maintaining the desired carrier concentration through controlled oxygen exposure
Solution Approach 2:
The patent uses an oxygen atmosphere during heat treatment to prevent hydrogen contamination and maintain a clean environment for the oxide semiconductor, creating an inert-like condition that protects against harmful impurity incorporation
2Quantity of substance
If oxygen vacancies are present in the oxide semiconductor, then carrier supply increases, but electric characteristics are adversely affected
Solution Approach 1:
The patent performs heat treatment in an oxygen atmosphere before device operation to preemptively fill oxygen vacancies and reduce carrier supply from these defects, preventing threshold voltage shifts before they occur during device operation
Solution Approach 2:
The patent uses oxygen as a strong oxidant during heat treatment to accelerate the filling of oxygen vacancies in the oxide semiconductor film, rapidly restoring stoichiometry and eliminating harmful carrier sources
3Area of stationary object
If amorphous silicon is used for transistors, then larger substrate area can be covered, but field-effect mobility is low
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to oxide semiconductor, which enables both large-area coverage and improved field-effect mobility by utilizing the unique properties of oxide semiconductors that support high mobility in amorphous or polycrystalline forms
4Speed
If polycrystalline silicon is used for transistors, then field-effect mobility is high, but large substrate area coverage is difficult
Solution Approach 1:
The patent changes the crystallinity parameter of the semiconductor material, using oxide semiconductors that can achieve high field-effect mobility in amorphous or polycrystalline forms, thereby enabling both high speed performance and large-area coverage that polycrystalline silicon cannot achieve
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 approach effectively reduces oxygen vacancies and hydrogen contamination, leading to improved electric characteristics, including reduced threshold voltage shifts and enhanced mobility in oxide semiconductor transistors.
Implementation Method 1
the first oxide insulating film from which part of oxygen is released by heating
Implementation Method 2
the second oxide insulating film which prevents diffusion of oxygen to the outside
Data Source
AI summary
A transistor including an oxide semiconductor with favorable electric characteristics and a manufacturing method thereof are provided. A semiconductor device includes a transistor. The transistor includes an oxide semiconductor film over a base insulating film, a gate electrode overlapping with the oxide semiconductor film with a gate insulating film interposed therebetween, and a pair of electrodes in contact with the oxide semiconductor film and serving as a source electrode and a drain electrode. The base insulating film includes a first oxide insulating film partly in contact with the oxide semiconductor film and a second oxide insulating film in the periphery of the first oxide insulating film. An end portion of the oxide semiconductor film which crosses the channel width direction of the transistor is located over the second oxide insulating film.