Dual-Gate Oxide Semiconductor Transistor With Low-Resistance Gate Link
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Solution Overview
Problem
Transistors using oxide semiconductor films face issues with high connection resistance between gate electrodes, leading to unstable electrical characteristics and increased power consumption, along with challenges from oxygen vacancies affecting carrier supply and threshold voltage shifts.
Innovation Solution
A semiconductor device with a dual gate structure incorporating an oxide semiconductor film, where the connection resistance is reduced by using a metal film and an oxide conductive film, and excess oxygen is added to the insulating films to minimize oxygen vacancies, stabilizing electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dual gate structure is used to increase field-effect mobility and on-state current, then electrical performance is improved, but connection resistance between gate electrodes increases
Solution Approach 1:
The patent applies composite materials by forming a stacked structure of metal film and oxide conductive film as the connection electrode. The metal film (first conductive layer) provides low resistance, while the oxide conductive film (second conductive layer) offers good interface characteristics and stability, creating a composite connection electrode that simultaneously reduces connection resistance and maintains electrical stability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the connection electrode by controlling the thickness of each layer (metal film: 5-50 nm, oxide conductive film: 5-100 nm) and adjusting the oxygen concentration in the oxide conductive film to 10-80 at%. These parameter optimizations reduce connection resistance while preventing oxygen vacancy formation.
2Adaptability or versatility
If oxide semiconductor film is used in channel region, then transistor functionality is achieved, but oxygen vacancies cause threshold voltage shifts and electrical characteristic changes
Solution Approach 1:
The patent applies preliminary anti-action by adding excess oxygen to the insulating films (particularly the second insulating film in contact with the oxide semiconductor) before oxygen vacancies can form in the channel region. This preventive oxygen supply counteracts potential oxygen loss during subsequent processing steps, maintaining the stoichiometry and electrical stability of the oxide semiconductor channel.
Solution Approach 2:
The oxide conductive film in the connection electrode serves dual functions: it provides electrical conduction and simultaneously acts as an oxygen reservoir that can supply oxygen to the oxide semiconductor channel region, preventing oxygen vacancy formation and maintaining channel stability.
3Reliability
If connection resistance is reduced using metal film and oxide conductive film, then electrical stability is improved, but device structure becomes more complex
Solution Approach 1:
The oxide conductive film in the connection electrode performs multiple functions simultaneously: it provides electrical conduction, serves as an oxygen barrier and reservoir, ensures good interface characteristics with the gate insulating film, and prevents oxygen vacancy formation in the channel. This multi-functionality reduces the need for additional separate structures, offsetting the apparent complexity increase.
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 connection resistance, stabilizes electrical characteristics, and minimizes power consumption by using a dual gate structure with metal and oxide conductive films, and by adding excess oxygen to the insulating films to reduce oxygen vacancies.
Implementation Method 1
connection resistance between one gate electrode and the other gate electrode is preferably as low as possible
Implementation Method 2
excess oxygen is added to the insulating films to minimize oxygen vacancies
Data Source
AI summary
The transistor includes a first gate electrode, a first insulating film over the first gate electrode, an oxide semiconductor film over the first insulating film, a source electrode over the oxide semiconductor film, a drain electrode over the oxide semiconductor film, a second insulating film over the oxide semiconductor film, the source electrode, and the drain electrode, and a second gate electrode over the second insulating film. The first insulating film includes a first opening. A connection electrode electrically connected to the first gate electrode through the first opening is formed over the first insulating film. The second insulating film includes a second opening that reaches the connection electrode. The second gate electrode includes an oxide conductive film and a metal film over the oxide conductive film. The connection electrode and the second gate electrode are electrically connected to each other through the metal film.