Semiconductor device including transistor with doped oxide semiconductor and method for manufacturing the semiconductor device
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving stable and reliable electrical characteristics due to oxygen vacancies and impurity diffusion, which affect the performance and reliability of transistors used in display devices.
Innovation Solution
A semiconductor device structure is developed with a metal oxide semiconductor layer, a gate insulating layer containing an oxide, and a conductive layer, where an impurity element like phosphorus or boron is introduced to create a concentration gradient, reducing oxygen vacancies and maintaining low electrical resistance in the source and drain regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor layer is used to achieve high field-effect mobility, then transistor performance is improved, but oxygen vacancies and impurity diffusion occur leading to unstable electrical characteristics
Solution Approach 1:
The patent applies different doping concentrations of phosphorus in different regions: higher concentration in source/drain regions to reduce resistance and stabilize electrical characteristics, and lower concentration in the channel region to maintain high field-effect mobility. This local differentiation resolves the contradiction by optimizing each region's properties for its specific function.
Solution Approach 2:
The patent changes the phosphorus concentration parameter across different regions of the oxide semiconductor layer. By controlling the phosphorus concentration to be higher in source/drain regions and lower in the channel region, the patent simultaneously achieves stable electrical characteristics (through high phosphorus concentration) and high field-effect mobility (through low phosphorus concentration in channel).
2Reliability
If phosphorus doping is increased to reduce electrical resistance in source and drain regions, then conductivity is improved, but carrier density increases which may affect transistor performance
Solution Approach 1:
The patent applies high phosphorus concentration specifically in source/drain regions where low resistance is critical, while maintaining low phosphorus concentration in the channel region where high mobility is essential. This localized approach reduces overall carrier density impact while achieving the desired conductivity improvement in source/drain regions.
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 results in a semiconductor device with improved electrical characteristics and high reliability by reducing oxygen vacancies and maintaining low carrier density, leading to enhanced performance in transistors for display devices.
Implementation Method 1
the semiconductor layer includes a first region overlapping with the first conductive layer and a second region not overlapping with the first conductive layer. The first insulating layer includes a third region overlapping with the first conductive layer and a fourth region not overlapping with the first conductive layer. Furthermore, the second region and the fourth region contain a first element.
Implementation Method 2
the first element is preferably phosphorus, boron, magnesium, aluminum, or silicon. Moreover, it is preferable that the first element exist in a state of being bonded to oxygen.
Data Source
AI summary
A semiconductor device having favorable electrical characteristics is provided. A semiconductor device having stable electrical characteristics is provided. A highly reliable semiconductor device is provided. The semiconductor device includes a semiconductor layer, a first insulating layer, and a first conductive layer. The semiconductor layer includes an island-shaped top surface. The first insulating layer is provided in contact with a top surface and a side surface of the semiconductor layer. The first conductive layer is positioned over the first insulating layer and includes a portion overlapping with the semiconductor layer. In addition, the semiconductor layer includes a metal oxide, and the first insulating layer includes an oxide. The semiconductor layer includes a first region overlapping with the first conductive layer and a second region not overlapping with the first conductive layer. The first insulating layer includes a third region overlapping with the first conductive layer and a fourth region not overlapping with the first conductive layer. Furthermore, the second region and the fourth region contain phosphorus or boron.