Oxide Semiconductor Channel Engineering for Low Off-State Current
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Solution Overview
Problem
Transistors using silicon semiconductors in flat panel displays suffer from oxygen vacancies at the interface with conductive electrodes, leading to reduced electrical characteristics and increased off-state current, which affects the device's performance and reliability.
Innovation Solution
A semiconductor device with an oxide semiconductor film, where low-resistance regions are formed between the oxide semiconductor film and the source/drain electrodes, and a channel formation region is positioned between these regions, with controlled oxygen addition to reduce oxygen vacancies and improve electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive film is formed over an oxide semiconductor film to create source and drain electrodes, then contact resistance is reduced due to oxygen vacancy and hydrogen formation, but oxygen vacancy is also caused in the channel formation region leading to electrical characteristic defects
Solution Approach 1:
The patent applies local quality by creating distinct regions with different oxygen concentrations within the oxide semiconductor film. Specifically, low-resistance regions are formed at the source/drain electrode interfaces where oxygen vacancy is permitted to reduce contact resistance, while the channel formation region maintains higher oxygen concentration to prevent electrical characteristic defects. This spatial differentiation of oxygen content allows simultaneous optimization of both contact resistance and channel electrical characteristics.
Solution Approach 2:
The oxide semiconductor film is segmented into functionally distinct regions: low-resistance regions adjacent to source/drain electrodes and a channel formation region separated from direct electrode contact. This segmentation is achieved through selective oxygen addition processes that treat different spatial zones differently, allowing the low-resistance regions to provide low contact resistance while the channel region maintains high electrical stability.
2Reliability
If oxygen is added to the oxide semiconductor film to reduce oxygen vacancy, then electrical characteristics are improved, but contact resistance increases due to reduced oxygen vacancy at the interface
Solution Approach 1:
The patent implements local quality by applying oxygen addition selectively to specific regions of the oxide semiconductor film. The channel formation region receives oxygen addition to reduce oxygen vacancy and improve electrical characteristics, while the low-resistance regions at the source/drain interfaces are either excluded from oxygen addition or receive less oxygen to maintain the oxygen vacancy necessary for low contact resistance. This localized treatment resolves the contradiction between improving electrical characteristics and maintaining low contact resistance.
3Reliability
If the conductive film material is easily diffused into the oxide semiconductor film by heat treatment, then low-resistance region is formed improving conductivity, but oxygen vacancy is caused in the channel formation region creating defects
Solution Approach 1:
The patent applies local quality by creating a structural configuration where the channel formation region is positioned to avoid direct contact with the conductive film, while low-resistance regions are formed at the source/drain electrode interfaces. This spatial arrangement allows conductive material diffusion to benefit the contact regions without adversely affecting the channel region, thereby improving conductivity without creating electrical characteristic defects in the channel.
Solution Approach 2:
The patent introduces an intermediary structure by forming low-resistance regions that act as buffer zones between the conductive film and the oxide semiconductor bulk. These intermediary regions absorb the harmful effects of oxygen vacancy and conductive material diffusion, protecting the channel formation region from damage while still benefiting from the low-resistance contact provided by the diffused conductive material.
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 reduces oxygen vacancies in the channel formation region, enhancing the semiconductor device's electrical characteristics, mobility, and switching performance while minimizing off-state current and power consumption.
Implementation Method 1
oxygen in the oxide semiconductor film is bonded to the conductive material. The bonding causes oxygen vacancy in a region of the oxide semiconductor film in the vicinity of an interface with the conductive film
Implementation Method 2
the material of the conductive film is a conductive material which is easily diffused into the oxide semiconductor film by heat treatment
Data Source
AI summary
A semiconductor device having a reduced amount of oxygen vacancy in a channel formation region of an oxide semiconductor is provided. Further, a semiconductor device which includes an oxide semiconductor and has improved electric characteristics is provided. Furthermore, a methods for manufacturing the semiconductor device is provided. An oxide semiconductor film is formed; a conductive film is formed over the oxide semiconductor film at the same time as forming a low-resistance region between the oxide semiconductor film and the conductive film; the conductive film is processed to form a source electrode and a drain electrode; and oxygen is added to the low-resistance region between the source electrode and the drain electrode, so that a channel formation region having a higher resistance than the low-resistance region is formed and a first low-resistance region and a second low-resistance region between which the channel formation region is positioned are formed.