Oxide Semiconductor TFT Channel Stability
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Solution Overview
Problem
Oxide semiconductor-based thin film transistors (TFTs) face instability issues due to hydrogen and oxygen diffusion, particularly when miniaturized, leading to changes in characteristics and potential conductivity loss, which affects the performance of display and sensor devices.
Innovation Solution
A TFT structure with an oxide semiconductor, a gate electrode, and a gate insulating film, where the channel region has a specific length and the source and drain regions are optimized with ion implantation and silicon nitride films to maintain stable resistance and prevent hydrogen diffusion into the channel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the channel length is reduced to miniaturize the TFT, then the device size is reduced, but hydrogen diffuses into the channel region causing characteristic changes and potential conductivity loss
Solution Approach 1:
The patent applies preliminary action by forming a hydrogen barrier film (silicon nitride or aluminum oxide) over the oxide semiconductor layer before hydrogen diffusion can occur. This preventive measure blocks hydrogen from the source and drain regions from diffusing into the channel region, thereby maintaining TFT characteristic stability even when the channel length is reduced for miniaturization
Solution Approach 2:
The patent introduces an intermediary substance (hydrogen barrier film made of silicon nitride or aluminum oxide) that acts as a mediator between the source/drain regions and the channel region. This intermediary layer prevents harmful hydrogen diffusion while allowing the TFT to function properly at miniaturized dimensions
2Object-affected harmful factors
If hydrogen is supplied to reduce source and drain region resistance, then the resistance is reduced, but hydrogen diffusion into the channel region causes characteristic changes
Solution Approach 1:
The patent applies segmentation by dividing the oxide semiconductor layer into functionally distinct regions: source region, drain region, and channel region. By selectively controlling hydrogen distribution in each region through the hydrogen barrier film, the patent reduces source and drain resistance while preventing hydrogen from entering the channel region, thereby maintaining characteristic stability
Solution Approach 2:
The patent applies local quality by creating different hydrogen concentration levels in different regions of the oxide semiconductor. The source and drain regions have higher hydrogen content for reduced resistance, while the channel region maintains low hydrogen content for stable characteristics, achieved through the hydrogen barrier film that allows localized hydrogen supply
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 ensures stable TFT characteristics even at miniaturized sizes, enabling high-definition displays and high-resolution sensors by maintaining low resistance in source and drain regions while keeping the channel region resistant, thus preventing conductivity issues.
Implementation Method 1
it has been found that oxygen supplied from a gate insulating film to a channel region contributes to maintaining high resistance
Implementation Method 2
hydrogen is supplied from a silicon nitride film (SiN) or the like to the source region and the drain region, whereby the oxide semiconductor can be reduced and the resistance can be reduced
Implementation Method 3
the oxide semiconductor can be reduced and the resistance can be reduced
Implementation Method 4
there is a technique of diffusing hydrogen into the source and drain regions by exposing the source and drain regions to plasma containing a large amount of hydrogen
Data Source
AI summary
The present invention addresses the problem of: realizing a TFT that uses an oxide semiconductor and that is capable of maintaining stable characteristics even in the case where the TFT is miniaturized; and realizing a display device that has high-definition pixels using such a TFT. To solve this problem, the present invention has the following configuration. A semiconductor device including an oxide semiconductor TFT formed using an oxide semiconductor film 109, the semiconductor device being characterized in that: the channel length of the oxide semiconductor TFT is 1.3 to 2.3 μm; and the sheet resistance of a source region 1092 and a drain region 1091 of the oxide semiconductor film 109 is 1.4 to 20 KΩ/□.