Nitrogen Silicon Gate Insulator for Oxide Semiconductor ESD Protection
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Solution Overview
Problem
The challenge is to develop a semiconductor device with oxide semiconductors that has high reliability and electrical stability, while minimizing changes to existing transistor structures, process conditions, and production apparatuses, and preventing yield decreases due to electrostatic discharge damage.
Innovation Solution
A semiconductor device is designed with a silicon film containing nitrogen as the gate insulating layer and an oxide insulating layer containing metal elements from the oxide semiconductor layer, stacked in a specific order, which increases the physical thickness of the gate insulating layer, reducing electrostatic discharge damage and improving interface stability between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate insulating layer (silicon oxide film) is used for oxide semiconductor transistors, then the transistor structure remains simple and compatible with existing processes, but the interface properties are poor and reliability is reduced
Solution Approach 1:
The gate insulating layer is formed as a composite structure combining a silicon oxide film and a silicon nitride film. The silicon oxide film provides good interface properties with the oxide semiconductor layer, while the silicon nitride film contributes higher relative permittivity and improved withstand voltage. This composite approach resolves the contradiction by achieving both good interface properties and enhanced reliability without completely redesigning the transistor structure.
Solution Approach 2:
The gate insulating layer structure is designed to serve multiple functions: the silicon oxide film component ensures excellent interface properties with the oxide semiconductor, while the silicon nitride film component provides higher permittivity for improved capacitance and withstand voltage. This multi-functional design allows a single gate insulating layer structure to address both interface quality and electrical stability requirements.
2Reliability
If the gate insulating layer thickness is increased to improve withstand voltage and reduce electrostatic discharge damage, then reliability against ESD improves, but the physical thickness increases and may affect device integration
Solution Approach 1:
The invention changes the material composition parameters of the gate insulating layer by incorporating silicon nitride film with higher relative permittivity. This allows achieving the required capacitance and withstand voltage with a optimized thickness that balances ESD protection requirements with device integration constraints. The parameter change in material composition enables thinner while more effective gate insulating layers.
3Productivity
If existing mass production technology for silicon-based semiconductors is used for oxide semiconductors, then productivity and cost are improved, but the mechanism of carrier generation is greatly different leading to poor interface properties
Solution Approach 1:
The invention applies local quality by using a silicon oxide film specifically at the interface with the oxide semiconductor layer to ensure excellent interface properties, while using silicon nitride film in other regions of the gate insulating layer to provide higher permittivity and withstand voltage. This localized material selection allows the structure to maintain good interface characteristics while benefiting from mass production compatibility.
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 configuration enhances the semiconductor device's reliability and stability by reducing charge trapping and photodegradation, while allowing for mass production at low cost using existing technology, and effectively prevents yield decreases from electrostatic discharge.
Implementation Method 1
The silicon film containing nitrogen has a higher relative permittivity than a silicon oxide film and therefore needs a larger thickness for an equivalent capacitance. Thus, when the silicon film containing nitrogen is used for the gate insulating layer, the physical thickness of the gate insulating layer can be increased, which makes it possible to reduce a decrease in withstand voltage
Data Source
AI summary
A highly reliable semiconductor device the yield of which can be prevented from decreasing due to electrostatic discharge damage is provided. A semiconductor device is provided which includes a gate electrode layer, a gate insulating layer over the gate electrode layer, an oxide insulating layer over the gate insulating layer, an oxide semiconductor layer being above and in contact with the oxide insulating layer and overlapping with the gate electrode layer, and a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer. The gate insulating layer includes a silicon film containing nitrogen. The oxide insulating layer contains one or more metal elements selected from the constituent elements of the oxide semiconductor layer. The thickness of the gate insulating layer is larger than that of the oxide insulating layer.