Oxide Semiconductor Transistor Hydrogen Diffusion Control
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Solution Overview
Problem
Variations in electric characteristics of transistors using oxide semiconductors, such as IGZO, can lead to malfunctions and reduced yield in semiconductor devices due to hydrogen concentration and oxygen vacancy issues, necessitating control of these parameters to enhance reliability and reduce power consumption.
Innovation Solution
A semiconductor device structure with an oxide semiconductor layer, source and drain electrodes, and a gate electrode is implemented, where the oxide semiconductor layer is divided into regions with varying hydrogen concentrations and oxygen vacancy densities, and an insulating layer is used to block hydrogen diffusion and oxygen release, employing specific alloys and materials to stabilize the channel formation region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor is used in transistor channel formation region, then next-generation thin film transistor performance is achieved, but variations in electric characteristics occur due to hydrogen concentration and oxygen vacancy issues
Solution Approach 1:
The oxide semiconductor layer is divided into a channel formation region and source/drain regions with different hydrogen concentration requirements. The channel formation region is designed to have low hydrogen concentration for stability, while source/drain regions can have higher hydrogen concentration for conductivity, resolving the contradiction by spatial segmentation of functional requirements
Solution Approach 2:
An insulating layer is introduced as an intermediary between external hydrogen sources and the oxide semiconductor layer. This insulating layer acts as a barrier to prevent hydrogen diffusion into the channel formation region, thereby maintaining low hydrogen concentration and stable electric characteristics without requiring complex manufacturing controls
2Power
If hydrogen concentration in oxide semiconductor is increased, then conductivity in source and drain regions is improved, but electric characteristics variation increases
Solution Approach 1:
Different hydrogen concentration levels are applied to different regions of the oxide semiconductor: low hydrogen concentration in the channel formation region for stability, and high hydrogen concentration in source/drain regions for conductivity. This local differentiation resolves the contradiction by optimizing each region for its specific function
Solution Approach 2:
The oxide semiconductor is segmented into functionally distinct regions with controlled hydrogen concentrations. The channel formation region maintains low hydrogen for consistent electric characteristics, while source/drain regions have high hydrogen for improved conductivity, achieving both goals simultaneously through spatial segmentation
3Ease of manufacture
If oxide semiconductor layer is exposed to hydrogen sources, then manufacturing process is simplified, but hydrogen diffusion increases causing electric characteristics variation
Solution Approach 1:
An insulating layer is formed beforehand to cover and protect the oxide semiconductor layer from external hydrogen sources during subsequent manufacturing processes. This preventive barrier allows simplified manufacturing processes while maintaining hydrogen concentration stability in the channel formation region
Solution Approach 2:
The insulating layer serves as an intermediary barrier between hydrogen-containing materials/processes and the oxide semiconductor. It allows the manufacturing process to proceed with hydrogen-containing materials while preventing harmful hydrogen diffusion into the channel formation region, thus maintaining reliability without complicating manufacturing
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
This structure reduces variations in electric characteristics, improves reliability, and achieves low off-state current and power consumption, making the semiconductor device more stable and efficient.
Implementation Method 1
an insulating layer which blocks diffusion of hydrogen from the source electrode or the drain electrode to the channel formation region
Implementation Method 2
an insulating layer which blocks release of oxygen from the oxide semiconductor layer
Data Source
AI summary
The reliability of a semiconductor device is increased by suppression of a variation in electric characteristics of a transistor as much as possible. As a cause of a variation in electric characteristics of a transistor including an oxide semiconductor, the concentration of hydrogen in the oxide semiconductor, the density of oxygen vacancies in the oxide semiconductor, or the like can be given. A source electrode and a drain electrode are formed using a conductive material which is easily bonded to oxygen. A channel formation region is formed using an oxide layer formed by a sputtering method or the like under an atmosphere containing oxygen. Thus, the concentration of hydrogen in a stack, in particular, the concentration of hydrogen in a channel formation region can be reduced.