Oxide Semiconductor Layer Si Concentration Gradient
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Solution Overview
Problem
Existing semiconductor devices with thin film transistors face challenges in achieving high electric characteristics and reliability, particularly in maintaining stability and reducing off-current over long-term use due to crystallization issues in oxide semiconductor layers.
Innovation Solution
Incorporating a concentration gradient of SiOx in the oxide semiconductor layer, using a combination of insulating materials like silicon oxide, silicon nitride, or aluminum oxide, to hinder crystallization and enhance heat resistance, with a sputtering method to deposit layers with varying Si-element concentrations, ensuring an amorphous structure that reduces off-current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an oxide semiconductor layer is used in thin film transistors, then the device can achieve transparent and flexible characteristics, but the oxide semiconductor layer tends to crystallize over time, leading to degraded electric characteristics and reduced reliability
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of SiOx within the oxide semiconductor layer, where the SiOx concentration varies from the gate electrode interface toward the upper surface. This non-uniform distribution allows different regions of the same layer to serve different functions: the region near the gate electrode maintains good electrical characteristics while the region farther away prevents crystallization, thus resolving the contradiction between transparency/flexibility and long-term reliability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the oxide semiconductor layer by controlling the SiOx concentration gradient. Specifically, it adjusts the SiOx concentration to be 0.01-5 atomic % near the gate electrode interface and 0.1-10 atomic % farther away. This parameter change transforms the uniform oxide semiconductor layer into a functionally differentiated structure that simultaneously achieves transparency, flexibility, and long-term stability.
2Temperature
If the oxide semiconductor layer is made amorphous to prevent crystallization, then heat resistance improves, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent applies preliminary action by pre-mixing SiOx particles into the oxide semiconductor target material before deposition. This ensures that SiOx is uniformly distributed in the target, and during sputtering, the mechanical mixing and transport processes naturally create the desired concentration gradient in the deposited film. This preliminary preparation simplifies the manufacturing process while achieving precise gradient control.
Solution Approach 2:
The patent replaces complex post-deposition processing with a sputtering-based deposition process that inherently creates the SiOx concentration gradient through controlled deposition conditions. By using sputtering with a pre-mixed target, the gradient is formed during deposition itself rather than requiring subsequent mechanical or chemical processing steps, thus improving manufacturing precision.
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 approach results in improved heat resistance, reduced characteristic variation, and lower off-current in thin film transistors, enhancing the overall electric performance and reliability of semiconductor devices.
Implementation Method 1
a sputtering method with use of a first oxide semiconductor target and then by a sputtering method with use of a second oxide semiconductor target containing SiO2
Implementation Method 2
SiOx (x>0) which hinders crystallization is contained in the oxide semiconductor layer, which enables improvement of the heat resistance
Data Source
AI summary
A semiconductor device including a thin film transistor which includes an oxide semiconductor layer and has high electric characteristics and reliability. Film deposition is performed using an oxide semiconductor target containing an insulator (an insulating oxide, an insulating nitride, silicon oxynitride, aluminum oxynitride, or the like), typically SiO2, so that the semiconductor device in which the Si-element concentration in the thickness direction of the oxide semiconductor layer has a gradient which increases in accordance with an increase in a distance from a gate electrode is realized.