Nitride Semiconductor Device Electric Field Distribution
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Solution Overview
Problem
Nitride semiconductor devices face challenges in effectively utilizing high breakdown voltage capabilities due to electric field concentration at the edges of gate and field plate electrodes, leading to reduced breakdown voltage and increased on-resistance.
Innovation Solution
A semiconductor device structure is implemented with a nitride semiconductor layer stack, including a first nitride semiconductor layer, a second layer with a larger band gap, and a third layer with a smaller band gap, where the gate electrode is positioned between the second and third layers without being in contact with the third layer, and an insulating film is used to distribute the electric field uniformly, preventing local enhancements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional nitride semiconductor device structure is used, then high breakdown voltage capability is achieved, but electric field concentration at electrode edges reduces the effective breakdown voltage and increases on-resistance
Solution Approach 1:
The patent introduces a field plate electrode that extends in the planar direction (parallel to the substrate surface) beyond the gate electrode edge, and a protrusion structure that extends in the vertical direction. This multi-dimensional extension of the electrode structure redistributes the electric field in both lateral and vertical dimensions, preventing concentration at the gate edge while maintaining high breakdown voltage capability.
Solution Approach 2:
The field plate electrode acts as an intermediary between the gate electrode and the drain region. It distributes the electric field uniformly across the semiconductor surface and prevents direct field concentration at the gate edge. The insulating film between the field plate and semiconductor surface further mediates the electric field distribution, enabling uniform field characteristics.
2Volume of moving object
If the gate electrode is positioned close to the third nitride semiconductor layer, then device size is reduced, but electric field concentration increases causing higher on-resistance
Solution Approach 1:
The field plate electrode extends in the planar direction beyond the gate electrode, creating a lateral extension that distributes the electric field without requiring increased vertical spacing. This allows the device to maintain compact vertical dimensions while achieving uniform electric field distribution through lateral expansion, thus reducing on-resistance without increasing overall device size.
3Device complexity
If the electric field is allowed to concentrate at electrode edges, then simpler device structure is achieved, but breakdown voltage performance deteriorates
Solution Approach 1:
The device structure is segmented into distinct functional regions: the gate electrode for control, the field plate electrode for field distribution, and the protrusion structure for vertical field management. This segmentation allows each component to perform its specific function optimally - the field plate distributes the field laterally while the protrusion manages vertical field concentration, together achieving high breakdown voltage without excessive complexity.
Solution Approach 2:
The protrusion structure extends vertically from the gate electrode or field plate, adding a vertical dimension to the field distribution mechanism. This vertical extension creates a gradual field transition zone that prevents sharp field concentration at horizontal edges, thereby improving breakdown voltage performance while maintaining a relatively simple planar layout.
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 enhances breakdown voltage and reduces on-resistance by ensuring a uniform electric field distribution, allowing the device to operate reliably in normally-off mode and enabling downsizing while maintaining high breakdown voltage characteristics.
Implementation Method 1
an insulating film is used to distribute the electric field uniformly, preventing local enhancements
Implementation Method 2
The second semiconductor layer has a larger band gap than the first semiconductor layer, and the third semiconductor layer has a smaller band gap than the second semiconductor layer
Data Source
AI summary
According to one embodiment, a semiconductor device includes a first semiconductor layer; a second semiconductor layer having a larger band gap than the first semiconductor layer; a third semiconductor layer having a smaller band gap than the second semiconductor layer; a first electrode being in contact with the third semiconductor layer; a second electrode being in contact with the third semiconductor layer; and a third electrode provided between the third semiconductor layer in contact with the first electrode, the second semiconductor layer directly below the first electrode, and the first semiconductor layer directly below the first electrode, and the third semiconductor layer in contact with the second electrode, the second semiconductor layer directly below the second electrode, and the first semiconductor layer directly below the second electrode, being in contact with the third semiconductor layer, the second semiconductor layer, and the first semiconductor layer via insulating film.