Oxide Semiconductor Insulating Stack for Stable Transistor Characteristics
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Solution Overview
Problem
Existing semiconductor devices using metal oxide materials face challenges in achieving stable and reliable electrical characteristics due to issues with impurity diffusion and hydrogen/water absorption, which affect the performance and reliability of transistors.
Innovation Solution
A semiconductor device structure is designed with a stacked insulating layer comprising silicon nitride, silicon oxynitride, and silicon oxide films, where the middle layer has a higher oxygen content and lower nitrogen content, and the top layer has a higher nitrogen content and lower oxygen content, to prevent impurity diffusion and enhance oxygen supply, thereby stabilizing the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple insulating layer structure is used, then device complexity is reduced, but impurity diffusion and hydrogen/water absorption increase, worsening electrical stability
Solution Approach 1:
The insulating layer is divided into three distinct films (first, second, and third insulating films) with different compositions and functions. The first film (higher nitrogen) acts as a barrier layer, the second film (higher oxygen) serves as an oxygen supply layer, and the third film (higher nitrogen) provides another barrier layer. This segmentation allows each layer to perform its specific function, preventing impurity diffusion while maintaining electrical stability.
Solution Approach 2:
The insulating layer uses a composite structure combining different insulating materials with specific oxygen and nitrogen content ratios. By stacking films with varying compositions (silicon oxide, silicon oxynitride, silicon nitride), the structure achieves both impurity barrier functionality and oxygen supply capability, resolving the contradiction between structural simplicity and electrical reliability.
2Object-affected harmful factors
If the insulating layer has high nitrogen content, then impurity diffusion is reduced, but oxygen supply to the semiconductor layer decreases, affecting carrier mobility
Solution Approach 1:
Different regions of the insulating layer have different compositions tailored to their specific functions. The first and third insulating films have higher nitrogen content to prevent impurity diffusion at the interfaces with the semiconductor layer and gate electrode. The second insulating film has higher oxygen content to supply oxygen to the semiconductor layer. This local quality differentiation resolves the contradiction between impurity barrier and oxygen supply requirements.
Solution Approach 2:
The second insulating film with higher oxygen content acts as an intermediary layer between the semiconductor layer and the gate electrode structure. It mediates the oxygen supply function while the first and third high-nitrogen films provide impurity barrier functions, allowing the system to achieve both impurity protection and oxygen supply without direct conflict.
3Reliability
If oxygen content in the insulating layer is increased, then carrier mobility is improved, but hydrogen/water absorption increases, reducing device reliability
Solution Approach 1:
The insulating layer structure assigns different compositional qualities to different layers. The second insulating film has higher oxygen content specifically positioned to supply oxygen to the semiconductor layer for improved carrier mobility. The first and third films have higher nitrogen content to provide barrier functions against hydrogen and water absorption. This localized quality assignment resolves the contradiction between oxygen supply and hydrogen/water absorption.
Solution Approach 2:
The structure converts the potential harm of high oxygen content (increased hydrogen/water absorption) into a benefit by spatially separating the oxygen supply function (second film) from the barrier function (first and third films). The high-oxygen region is confined to where it is needed for oxygen supply, while high-nitrogen regions provide protection against hydrogen/water absorption, transforming what could be a harmful effect into a controlled, beneficial arrangement.
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 proposed structure enhances the electrical stability and reliability of the semiconductor device by reducing impurity diffusion and hydrogen/water absorption, leading to improved carrier mobility and reduced threshold voltage fluctuations.
Implementation Method 1
the first 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 amount of the nitrogen included in the second insulating film is smaller than the amount of the nitrogen included in the first insulating film and larger than the amount of nitrogen included in the third insulating film
Implementation Method 2
The amount of the oxygen included in the second insulating film is larger than the amount of oxygen included in the first insulating film and smaller than the amount of the oxygen included in the third insulating film
Implementation Method 3
The first insulating film includes silicon and nitrogen... The third insulating film includes silicon and oxygen... to prevent impurity diffusion and enhance oxygen supply, thereby stabilizing the semiconductor layer
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. The 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 first 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 second insulating layer includes an oxide. The third insulating film includes a part in contact with the semiconductor layer. The first insulating film includes silicon and nitrogen. The second insulating film includes silicon, nitrogen, and oxygen. The third insulating film includes silicon and oxygen. The semiconductor layer includes indium and oxygen.