Oxide TFT Hydrogen Profile for Short-Channel Display Stability
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Solution Overview
Problem
In high-definition display apparatuses, the short channel effect in oxide semiconductor thin-film transistors leads to unstable characteristics, such as threshold voltage lowering and drain-induced barrier lowering, due to the small size of sub-pixels and the resulting short channel lengths of switching thin-film transistors.
Innovation Solution
The introduction of intermediate source and drain areas in the oxide semiconductor layer with lower hydrogen concentrations than the source and drain areas, and the use of silicon oxide and silicon nitride films with varying thicknesses and overlapping configurations to reduce the short channel effect without requiring a separate ion implantation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the channel length of the switching thin-film transistor is reduced to accommodate small sub-pixel sizes, then the sub-pixel integration is improved, but the transistor characteristics become unstable due to short channel effects
Solution Approach 1:
The patent applies local quality by creating intermediate source and drain areas with different hydrogen concentrations than the main source and drain areas. Specifically, the intermediate source area has a first hydrogen concentration and the intermediate drain area has a second hydrogen concentration, which are different from the hydrogen concentration in the main source and drain areas. This local variation in hydrogen concentration allows the transistor to maintain stable characteristics despite the short channel length, resolving the contradiction between small sub-pixel size and transistor stability.
2Reliability
If ion implantation is used to reduce short channel effect, then the transistor characteristics are stabilized, but the manufacturing process complexity increases
Solution Approach 1:
The patent replaces the mechanical/ion implantation process with a chemical vapor deposition process. Instead of using ion implantation to create the hydrogen concentration gradient in the oxide semiconductor layer, the patent uses a chemical atmosphere containing hydrogen to naturally form the intermediate source and drain areas with controlled hydrogen concentrations during the deposition process. This substitution eliminates the need for separate ion implantation equipment and processes, reducing manufacturing complexity while achieving the same transistor stabilization effect.
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 configuration stabilizes the characteristics of the thin-film transistors by reducing the short channel effect, ensuring reliable operation of the display apparatuses.
Implementation Method 1
a hydrogen concentration of each of the intermediate source area and the intermediate drain area is lower than a hydrogen concentration of each of the source area and the drain area
Data Source
AI summary
A display apparatus includes an oxide semiconductor layer on a substrate; a gate insulating film on the oxide semiconductor layer; a gate electrode on the gate insulating film; a first interlayer insulating film on the gate insulating film and the gate electrode; a second interlayer insulating film on the first interlayer insulating film; a source electrode connected to the oxide semiconductor layer; and a drain electrode spaced apart from the source electrode and connected to the oxide semiconductor layer, wherein the oxide semiconductor layer includes: a channel area overlapping the gate electrode; a source area connected to the source electrode; a drain area connected to the drain electrode; an intermediate source area between the channel and source areas; and an intermediate drain area between the channel and drain areas, wherein a hydrogen concentration of each of the intermediate source and drain areas is lower than that of each of the source and drain areas.