Thin-Film Transistor With Protection Layer Preventing Ion Diffusion
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Solution Overview
Problem
Conventional thin-film transistors experience unstable electrical characteristics due to the diffusion of doped charged ions from the source and drain electrodes into the semiconductor channel, leading to unchanged conductivity and inability to function as digital switches or analog amplifiers.
Innovation Solution
A thin-film transistor structure is developed with a semiconductor oxide layer of thickness not exceeding 20 nanometers, a protection layer defining the semiconductor channel, and an organic dielectric layer with through holes for the source and drain electrodes, preventing ion diffusion and enabling voltage control current source functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charged ions are doped into the contact area of source and drain electrodes to increase conductivity, then the electrode areas have lower resistivity and higher electron mobility, but the charged ions diffuse to the semiconductor channel causing unstable electrical characteristics
Solution Approach 1:
The patent divides the semiconductor oxide layer into two distinct functional regions: a semiconductor channel portion covered by the protection layer and non-channel portions exposed to the organic dielectric layer. This segmentation prevents charged ions from the source and drain electrodes from diffusing into the channel region, thereby maintaining electrical stability while allowing high conductivity in the contact areas.
Solution Approach 2:
The protection layer acts as an intermediary barrier between the semiconductor channel and the organic dielectric layer. This intermediate layer prevents direct contact and ion diffusion from the charged electrodes through the organic dielectric into the sensitive channel region, resolving the contradiction between needing conductive electrodes and maintaining channel stability.
2Ease of manufacture
If conventional doping method is used to increase electrode conductivity, then resistivity decreases and electron mobility increases, but after heating process the doped ions diffuse to semiconductor channel resulting in source and drain electrodes being substantially conducted
Solution Approach 1:
The patent segments the semiconductor oxide layer into channel and non-channel portions, allowing the non-channel portions to become highly conductive through ion diffusion from doped electrodes while the channel portion remains protected and maintains its semiconductor properties. This enables both easy manufacturing through conventional doping and reliable transistor switching functionality.
Solution Approach 2:
Different regions of the semiconductor oxide layer are given different functional qualities: the channel portion maintains semiconductor properties for switching control, while the non-channel portions under source and drain electrodes achieve high conductivity through ion diffusion. This local differentiation resolves the contradiction between ease of manufacture and device functionality.
3Quantity of substance
If doped charged ions are used to increase contact area conductivity, then electrode resistivity decreases, but the equivalent resistance of thin-film transistor becomes substantially unchanged regardless of gate electrode voltage
Solution Approach 1:
The patent segments the semiconductor oxide layer into protected channel portions and exposed non-channel portions. This allows charged ions to concentrate in the non-channel contact areas under source and drain electrodes, providing low resistance contacts, while the protected channel portions maintain their semiconductor properties and respond to gate voltage for voltage-controlled current source functionality.
Solution Approach 2:
The patent applies local quality differentiation where the semiconductor oxide layer has high ion concentration and high conductivity in the contact areas (non-channel portions) but maintains semiconductor properties and voltage sensitivity in the channel portions. This resolves the contradiction between achieving low contact resistance and maintaining voltage control functionality.
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 stabilizes the semiconductor channel, allowing for controlled conductivity and enabling the thin-film transistor to function as a voltage control current source, with improved resistance and current-voltage characteristics similar to MOSFETs.
Implementation Method 1
the organic dielectric layer includes a plurality of through holes... preventing ion diffusion
Implementation Method 2
A thickness of the semiconductor oxide layer is not larger than 20 nanometers (nm)... enabling voltage control current source functionality
Data Source
AI summary
A thin-film transistor comprises a substrate, a first electrode on the top surface of the substrate, an insulation layer on the top surface of the substrate and covering the first electrode, a semiconductor oxide layer on the top surface of the insulation layer, a protection layer on the top surface of the semiconductor oxide layer, an organic dielectric layer on the top surface of the semiconductor oxide layer and covering the protection layer, a source electrode and a drain electrode both penetrating the organic dielectric layer from the top surface thereof. A channel thickness of the semiconductor oxide layer is not thicker than 20 nanometers. The source electrode contacts the semiconductor oxide layer at the first side of the protection layer and the drain electrode contacts the semiconductor oxide layer at the second side, opposite to the first side, of the protection layer.