Oxide Semiconductor Transistor Oxygen Release Gate Insulator
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Solution Overview
Problem
Oxide semiconductor transistors with gate insulating films containing high hydrogen concentrations suffer from reliability issues due to oxygen deficiencies and hydrogen impurities, leading to fluctuating electrical characteristics and a shift in threshold voltage, making them less reliable.
Innovation Solution
A semiconductor device with a gate insulating film comprising a stacked structure of silicon oxynitride and an oxygen release type oxide film, where the oxygen release type oxide film supplies oxygen to the oxide semiconductor film, reducing hydrogen concentration and improving the reliability of the transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a gate insulating film with high hydrogen concentration (such as silicon nitride formed by PE-CVD) is used, then the transistor can be manufactured more easily, but oxygen deficiencies occur in the oxide semiconductor film and hydrogen impurities increase, leading to fluctuating electrical characteristics and reduced reliability
Solution Approach 1:
The gate insulating film is divided into multiple layers with different functions: a lower layer (silicon nitride or silicon oxide) that provides easy manufacturability and basic insulation, and an upper oxygen release layer (silicon oxide or silicon oxynitride) that supplies oxygen to prevent oxygen deficiencies. This segmentation allows each layer to optimize its specific function while working together to achieve both ease of manufacture and high reliability.
Solution Approach 2:
Different regions of the gate insulating film have different hydrogen concentrations and oxygen release properties. The lower layer has higher hydrogen concentration for ease of manufacture, while the upper layer has lower hydrogen concentration and high oxygen release capability. This local quality differentiation resolves the contradiction by providing appropriate properties at different locations within the same insulating film structure.
2Reliability
If hydrogen concentration in the gate insulating film is reduced to prevent oxygen deficiencies, then electrical characteristics become more stable, but the dielectric strength voltage and coverage of the gate insulating film become insufficient
Solution Approach 1:
The gate insulating film merges two different materials (silicon nitride/silicon oxide and silicon oxide/silicon oxynitride) that have complementary properties. The lower layer provides high dielectric strength and good coverage, while the upper layer provides oxygen release capability and low hydrogen concentration. Together, they achieve both electrical stability and sufficient dielectric strength.
Solution Approach 2:
The gate insulating film uses a composite structure combining materials with different characteristics. The silicon nitride or silicon oxide base provides mechanical strength and dielectric properties, while the silicon oxide or silicon oxynitride overlay provides oxygen release functionality. This composite material approach allows simultaneous achievement of dielectric strength and oxygen supply capability.
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 provides a semiconductor device with stable electrical characteristics and improved reliability by reducing oxygen deficiencies and hydrogen impurities, resulting in a low threshold voltage and high insulating properties.
Implementation Method 1
an oxygen release type oxide film from which oxygen is released by heating
Data Source
AI summary
Provided is a semiconductor device including an oxide semiconductor and having stable electrical characteristics. Specifically, a semiconductor device including an oxide semiconductor and including a gate insulating film with favorable characteristics is provided. Further, a method for manufacturing the semiconductor device is provided. The semiconductor device includes a gate electrode, a gate insulating film over the gate electrode, an oxide semiconductor film over the gate insulating film, and a source electrode and a drain electrode in contact with the oxide semiconductor film. The gate insulating film includes at least a silicon oxynitride film and an oxygen release type oxide film which is formed over the silicon oxynitride film. The oxide semiconductor film is formed on and in contact with the oxygen release type oxide film.