Oxide Semiconductor Layer Stack for Stable High-Mobility TFTs
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving favorable electrical characteristics and high reliability, particularly in display devices, due to issues with field-effect mobility and stability of electrical properties.
Innovation Solution
A semiconductor device is designed with a stacked-layer structure comprising a first insulating layer, a second insulating layer with a specific oxide film stack, a semiconductor layer containing indium and oxygen, and a conductive layer. The semiconductor layer may include regions with varying compositions of indium, gallium, and zinc to optimize electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor layer containing indium and gallium is used to achieve high field-effect mobility, then electrical performance is improved, but stability of electrical characteristics deteriorates
Solution Approach 1:
The patent applies local quality by creating a stacked-layer semiconductor structure where different layers have different compositions: the first semiconductor layer contains indium and gallium for high mobility, while the second semiconductor layer contains only indium for stability. This allows each layer to perform its specific function optimally, resolving the contradiction between mobility and stability.
Solution Approach 2:
The patent uses composite materials by combining multiple oxide semiconductor layers with different compositions (In-Ga-O and In-O) to form a stacked structure. This composite approach leverages the high mobility of indium-gallium oxide while the indium oxide layer provides stability, achieving both improved electrical performance and characteristic stability.
2Reliability
If a simple insulating layer structure is used to reduce device complexity, then manufacturing is simplified, but electrical characteristic stability deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the insulating layer into multiple stacked layers (first insulating layer, second insulating layer, third insulating layer) with different functions. The first layer provides interface quality, the second layer provides insulation, and the third layer provides protection, thereby achieving electrical stability through structured complexity.
Solution Approach 2:
The insulating layer structure uses composite materials by stacking different oxide layers (such as silicon oxide, silicon nitride, and oxygen-containing oxide layers) that work together to provide both electrical stability and manufacturing compatibility, resolving the contradiction between complexity and reliability.
3Productivity
If indium content in semiconductor layer is increased to improve field-effect mobility, then electrical performance is enhanced, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent segments the indium content distribution across different layers: the first semiconductor layer has high indium content (40-70 at%) for mobility, while the second layer has lower indium content (20-40 at%) for stability. This segmentation makes composition control more manageable than uniform high-indium structures.
Solution Approach 2:
The patent applies parameter changes by varying the indium and gallium content ratios between layers and controlling the thickness of each layer to optimize both mobility and manufacturability. The first layer uses In:Ga:O ratio of 40:10:50 to 70:10:20 while the second layer uses 20:10:70 to 40:10:50, providing controlled parameter variation.
Data Source
AI summary
A semiconductor device with favorable electrical characteristics is provided. A highly reliable semiconductor device is provided. A semiconductor device with stable electrical characteristics is provided. A semiconductor device includes a first insulating layer, a second insulating layer, a semiconductor layer, and a first conductive layer. The semiconductor layer, the second insulating layer, and the first conductive layer are stacked in this order over the first insulating layer. The second insulating layer has a stacked-layer structure in which a first insulating film, a second insulating film, and a third insulating film are stacked in this order. The first insulating film, the second insulating film, and the third insulating film each contain an oxide. The first insulating film includes a portion in contact with the semiconductor layer. The semiconductor layer contains indium, gallium, and oxygen and includes a region with an indium content percentage higher than a gallium content percentage.