GaN Bidirectional Switch Field-Plate Layout for Uniform Electric Field
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Solution Overview
Problem
Current GaN bidirectional switch devices for matrix converters require multiple power devices, increasing chip area and cost, and suffer from uneven electric field distribution and high device loss, leading to reduced performance and reliability.
Innovation Solution
A GaN bidirectional switch device design featuring a substrate, semiconductor epitaxial layer, first-level field plate dielectric layer, groove, and interconnecting field plate metals, which reduces the number of power devices needed and ensures uniform electric field distribution during the off state, enhancing withstand voltage and stability by inhibiting current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple power devices (two IGBTs in reverse parallel with diodes) are used to achieve bidirectional switching with reverse blocking ability, then the device can operate in four quadrants, but the chip area and cost increase, and device loss increases
Solution Approach 1:
The patent merges multiple power devices into a single GaN HEMT device structure. The GaN HEMT inherently provides bidirectional switching capability through its device physics, eliminating the need for separate IGBTs and diodes. This consolidation reduces chip area while maintaining four-quadrant operation capability, directly resolving the technical contradiction between versatility and area.
Solution Approach 2:
The GaN HEMT device is designed to perform multiple functions within a single device structure. It provides both switching functionality and reverse blocking capability through integrated design elements (such as the JFET region and drift layer), rather than requiring separate dedicated components. This multi-functionality reduces the overall device count and chip area while maintaining full four-quadrant operation.
2Adaptability or versatility
If multiple power devices (two IGBTs in reverse parallel with diodes) are used to achieve bidirectional switching, then reverse blocking ability is obtained, but the number of components and connecting lines increases, reducing system reliability
Solution Approach 1:
The patent combines reverse blocking ability and switching functionality into a single GaN HEMT device rather than using multiple separate components. This reduction in component count and interconnections directly improves system reliability by minimizing potential failure points and connection interfaces, while maintaining the required reverse blocking capability through integrated device design.
3Adaptability or versatility
If a conventional bidirectional switch structure is used, then reverse blocking is achieved, but electric field distribution in the withstand voltage region becomes uneven, reducing device performance
Solution Approach 1:
The patent implements localized structural modifications in specific regions of the GaN HEMT to optimize electric field distribution. The JFET region and drift layer are designed with specific doping profiles and geometries that create localized electric field control, ensuring uniform field distribution in the withstand voltage region while maintaining reverse blocking function. This local quality adjustment resolves the contradiction between reverse blocking capability and field distribution uniformity.
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 design reduces device volume, improves withstand voltage, and increases stability by maintaining functioning field plates during AC signal cycles, thereby enhancing the overall performance and reliability of the GaN bidirectional switch device.
Implementation Method 1
make the electric field distribution in the withstand voltage region more uniform, thereby improving the withstand voltage of the GaN bidirectional switch device
Implementation Method 2
inhibit capture of electrons in channels by defects on a surface or in an interior of the semiconductor epitaxial layer under the action of a high electric field during switching
Data Source
AI summary
A gallium nitride bidirectional switch device includes: a substrate, a semiconductor epitaxial layer and a first-level field plate dielectric layer sequentially stacked in that order; the semiconductor epitaxial layer is provided with an active area and a non-active area, the first-level field plate dielectric layer is located in the active area and extends to the non-active area, a groove penetrates the first-level field plate dielectric layer and the semiconductor epitaxial layer to expose the substrate and is located in the non-active area, two first-level field plate metals are spaced on the first-level field plate dielectric layer and located in the active area; and the two first-level field plate metals are connected through a first interconnecting metal to form a first field plate metal interconnecting structure, and a part of the first field plate metal interconnecting structure fills the groove and is connected with the substrate exposed by the groove.