Oxide-Semiconductor Thin-Film Transistor Interface Oxygen Hole Control
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Solution Overview
Problem
Existing thin-film transistors composed of oxide semiconductors face challenges in controlling oxygen holes at the interface layer, particularly on cheap glass substrates, leading to insufficient control over electric characteristics and fabrication reproducibility.
Innovation Solution
A method involving the formation of a thin-film device with a multi-layered structure, including interface layers with controlled oxygen hole densities, achieved through sequential oxidation and patterning of the oxide-semiconductor film without exposing it to atmosphere, to reduce oxygen hole defects and enhance electron mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If annealing is performed at 300 degrees centigrade or higher in oxidation atmosphere to reduce oxygen holes at the upper surface of the oxide-semiconductor film, then oxygen hole density at the upper surface is reduced, but oxygen holes at the lower surface (interface layer) remain uncontrollable
Solution Approach 1:
The patent applies preliminary action by forming a protective film (such as silicon oxide or silicon nitride) on the lower surface of the oxide-semiconductor film before completing the device structure. This protective film prevents oxygen hole generation at the interface layer during subsequent processing steps, thereby controlling oxygen holes at the interface layer before they can affect device performance and reproducibility.
Solution Approach 2:
The patent introduces an intermediary protective film between the oxide-semiconductor film and the underlying structure. This intermediary layer acts as a barrier that prevents oxygen diffusion and interface defect formation, thereby controlling oxygen holes at the interface layer without requiring high-temperature annealing that would cause metal diffusion.
2Reliability
If annealing is performed at 600 degrees centigrade or higher to oxidize the lower surface of the oxide-semiconductor film, then oxygen holes at the lower surface are reduced, but metal film diffusion into the oxide-semiconductor film occurs causing contamination
Solution Approach 1:
The patent applies preliminary action by forming a protective film (such as silicon oxide or silicon nitride) on the lower surface of the oxide-semiconductor film before completing the device structure. This protective film prevents oxygen hole generation at the interface layer during subsequent processing steps, thereby controlling oxygen holes at the interface layer before they can affect device performance and reproducibility.
Solution Approach 2:
The patent introduces an intermediary protective film between the oxide-semiconductor film and the underlying structure. This intermediary layer acts as a barrier that prevents oxygen diffusion and interface defect formation, thereby controlling oxygen holes at the interface layer without requiring high-temperature annealing that would cause metal diffusion.
3Reliability
If high-temperature annealing is used to control oxygen holes, then oxygen hole density is reduced, but substrate cost increases and metal diffusion occurs
Solution Approach 1:
The patent applies preliminary action by forming a protective film (such as silicon oxide or silicon nitride) on the lower surface of the oxide-semiconductor film before completing the device structure. This protective film prevents oxygen hole generation at the interface layer during subsequent processing steps, thereby controlling oxygen holes at the interface layer before they can affect device performance and reproducibility.
Solution Approach 2:
The patent introduces an intermediary protective film between the oxide-semiconductor film and the underlying structure. This intermediary layer acts as a barrier that prevents oxygen diffusion and interface defect formation, thereby controlling oxygen holes at the interface layer without requiring high-temperature annealing that would cause metal diffusion.
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 effectively controls oxygen hole density, improving the switching characteristics and reproducibility of thin-film transistors, enabling their use in display drivers with high fabrication yield on affordable glass substrates.
Implementation Method 1
oxidizing the oxide-semiconductor film to reduce a density of oxygen holes in at least one of the first and second interface layers
Data Source
AI summary
A method of forming a thin-film device includes forming an oxide-semiconductor film formed on the first electrical insulator, and forming a second electrical insulator formed on the oxide-semiconductor film, the oxide-semiconductor film defining an active layer. The oxide-semiconductor film is comprised of a first interface layer located at an interface with the first electrical insulator, a second interface layer located at an interface with the second electrical insulator, and a bulk layer other than the first and second interface layers. The method further includes oxidizing the oxide-semiconductor film to render a density of oxygen holes in at least one of the first and second interlayer layers is smaller than a density of oxygen holes in the bulk layer.