Oxide Semiconductor TFT With Segmented Channel Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional oxide semiconductor TFTs experience threshold voltage shifts due to ultraviolet light irradiation and negative bias stress, affecting their electric properties and reliability.
Innovation Solution
A thin film transistor (TFT) with an oxide semiconductor channel layer comprising multiple sub-layers of varying oxygen content, where a lower oxygen content first sub-layer is sandwiched between a higher oxygen content second sub-layer, which acts as a UV shielding layer, and the reactive oxygen/argon flow ratio in sputtering processes is adjusted to form these sub-layers, preventing threshold voltage shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the oxide semiconductor channel layer is made as a single uniform layer, then the manufacturing process is simple, but the threshold voltage shifts under UV light irradiation and negative bias stress
Solution Approach 1:
The oxide semiconductor channel layer is divided into multiple sub-layers with different oxygen contents. The first sub-layer has lower oxygen content while the second sub-layer has higher oxygen content, creating a structured composition that prevents threshold voltage shifts under UV light and negative bias stress while maintaining manufacturing feasibility through sequential deposition processes
Solution Approach 2:
Different regions of the oxide semiconductor channel layer are given different oxygen contents to perform different functions. The first sub-layer with lower oxygen content provides stable electrical properties, while the second sub-layer with higher oxygen content acts as a UV shielding layer, creating local quality variations that solve the threshold voltage stability problem
2Reliability
If the oxygen content in the oxide semiconductor channel layer is increased to prevent threshold voltage shifts, then the UV shielding capability improves, but the electrical conductivity decreases
Solution Approach 1:
The channel layer is segmented into sub-layers with different oxygen contents, allowing the first sub-layer to maintain high conductivity with lower oxygen while the second sub-layer provides UV shielding with higher oxygen content, thus resolving the contradiction between conductivity and UV protection
Solution Approach 2:
Different oxygen contents are locally distributed within the channel layer structure, with the lower oxygen first sub-layer providing electrical conductivity and the higher oxygen second sub-layer providing UV shielding, enabling each region to optimize its local function without compromising overall device performance
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 TFT exhibits improved electric properties and reliability by preventing threshold voltage shifts and shielding UV damage, maintaining stable performance.
Implementation Method 1
a reactive oxygen/argon flow ratio of a sputtering process of the first sub-layer ranges from about 0 to about 10, and a reactive oxygen/argon flow ratio of a sputtering process of the second sub-layer ranges from about 5 to about 80
Data Source
AI summary
A thin film transistor (TFT) including a gate, a gate insulator, an oxide semiconductor channel layer, a source, and a drain is provided. The gate insulator covers the gate, while the oxide semiconductor channel layer is configured on the gate insulator and located above the gate. The oxide semiconductor channel layer includes a first sub-layer and a second sub-layer located on the first sub-layer. An oxygen content of the first sub-layer is lower than an oxygen content of the second sub-layer. The source and the drain are configured on a portion of the second sub-layer. In addition, a fabricating method of the above-mentioned TFT is also provided.