Nitride Semiconductor Isolation Layout for Lower Output Capacitance
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Solution Overview
Problem
High output capacitance in semiconductor devices limits their performance in high-frequency power applications, as it leads to significant switching losses due to the capacitance between the drain electrode and the substrate or package, making it difficult to achieve both high breakdown field strength and high electron mobility.
Innovation Solution
The semiconductor device employs a multi-finger structure with separated wiring portions and element isolation areas in the nitride semiconductor layers, reducing the capacitance between the drain electrode and the substrate or package, and using a low relative permittivity insulation film to further minimize capacitance, thereby reducing output capacitance without increasing on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drain electrode is directly connected to the substrate or package, then the electrical connection is simple, but the capacitance between the drain electrode and substrate/package increases leading to high output capacitance and switching losses
Solution Approach 1:
The drain electrode is divided into multiple separated wiring portions (first wiring portion, second wiring portion, third wiring portion) that are spatially distributed and electrically connected through the element isolation area. This segmentation reduces the capacitance between the drain electrode and substrate/package by distributing the electrical connection across multiple smaller contact points rather than a large continuous area, thereby reducing switching losses while maintaining electrical connectivity.
Solution Approach 2:
The element isolation area serves as an intermediary structure between the separated wiring portions of the drain electrode. It provides electrical connection between the first, second, and third wiring portions while being positioned to minimize capacitance with the substrate or package. This intermediary structure enables the drain electrode to achieve low output capacitance without compromising electrical connectivity.
2Loss of energy
If a low relative permittivity insulation film is used, then the capacitance is reduced, but the insulation film material selection becomes more limited
Solution Approach 1:
The patent specifies that the insulation film should have a relative permittivity of 5 or less, which is a parameter change from conventional insulation films that typically have higher permittivity values. This parameter change enables significant reduction in output capacitance and switching losses. The patent provides specific material examples (nitride semiconductor, oxide semiconductor, silicon oxide, silicon nitride, silicon nitro oxide, fluorinated polymer) that meet this permittivity requirement, guiding material selection while achieving the desired electrical performance.
3Loss of energy
If the element isolation area extends into the second nitride semiconductor layer, then the capacitance between drain electrode and substrate is reduced, but the manufacturing precision requirement increases
Solution Approach 1:
The element isolation area extends in the vertical dimension (first direction) into the second nitride semiconductor layer, rather than only extending in the horizontal plane. This dimensional approach allows the element isolation area to achieve electrical isolation and capacitance reduction by positioning itself within the semiconductor layer structure, providing a degree of freedom in positioning that can accommodate manufacturing variations while maintaining the capacitance reduction effect.
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 enables a semiconductor device with low output capacitance, suitable for high-frequency power applications, by reducing the capacitance components and maintaining low on-state resistance, thus enhancing the device's performance in high breakdown field strength and electron mobility.
Implementation Method 1
using a low relative permittivity insulation film to further minimize capacitance, thereby reducing output capacitance
Implementation Method 2
The insulation film has a relative permittivity of 5 or less
Data Source
AI summary
A semiconductor device includes first and second nitride semiconductor layers. The second layer on the first nitride has a first region, a second region, and a third region between the first and second regions. A first gate electrode is in the first region and extends parallel to a surface of a substrate. A first source electrode is in the first region and extends in the first direction. A second gate electrode in the second region and extends in the first direction. A second source electrode is in the second region and extends in the first direction. A drain electrode coupled to a first and a second wiring. The first wiring directly contacts the second nitride semiconductor layer in the first region. The second wiring directly contacts the second nitride semiconductor layer in the second region. An insulation material is in the third region.