GaN Trench Gate Structure for Electric Field Distribution
Solution Overview
Problem
Semiconductor devices, such as transistors and diodes, face a trade-off between breakdown voltage and on-resistance, with silicon-based devices limiting further improvements, and the reliability of gate insulating layers in trench gate structures is a concern due to high electric field concentration.
Innovation Solution
A nitride semiconductor device with a specific gallium nitride layer structure and a trench gate structure is developed, incorporating an aluminum nitride gate insulating layer and a gate electrode, which includes a shallower trench with inclined side surfaces and p-type and n-type regions to reduce the electric field strength on the gate insulating layer, enhancing its reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench gate structure is used to reduce on-resistance, then the channel region per unit area increases, but the electric field concentrates on the gate insulating layer at the bottom of the trench, reducing its reliability
Solution Approach 1:
The patent applies local quality by creating regions with different impurity concentrations within the semiconductor layer. Specifically, it forms a first region with a first impurity concentration and a second region with a second impurity concentration that is lower than the first, adjacent to the gate insulating layer. This local variation in impurity concentration allows the electric field to be distributed more favorably, reducing concentration at critical points while maintaining overall device performance.
Solution Approach 2:
The patent employs parameter changes by systematically varying the impurity concentration parameter across different regions of the semiconductor layer. By controlling the impurity concentration to be lower in the second region adjacent to the gate insulating layer compared to the first region, the patent optimizes the electric field distribution. This parameter adjustment resolves the contradiction by reducing electric field concentration harmful effects while preserving the benefits of the trench gate structure for reducing on-resistance.
2Reliability
If the semiconductor material is changed from silicon to nitride semiconductor, then the breakdown voltage increases and on-resistance decreases, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the impurity concentration parameter across different regions of the nitride semiconductor layer. By controlling the impurity concentration to be lower in the second region adjacent to the gate insulating layer compared to the first region, the patent optimizes the electric field distribution. This parameter adjustment resolves the contradiction by reducing electric field concentration harmful effects while preserving the benefits of the trench gate structure for reducing on-resistance.
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 significantly improves the reliability of the gate insulating layer and reduces on-resistance by distributing the electric field and increasing the channel region per unit area, achieving a semiconductor device with enhanced performance.
Implementation Method 1
an electric field is concentrated on a gate insulating layer at a bottom of the trench, so that reliability of the gate insulating layer becomes a concern
Implementation Method 2
By using a nitride semiconductor such as gallium nitride as the semiconductor material of the semiconductor devices, the trade-off relationship determined by the semiconductor material can be improved. Therefore, it is possible to dramatically increase the breakdown voltage of the semiconductor devices
Implementation Method 3
it is possible to dramatically increase the breakdown voltage of the semiconductor devices and to dramatically reduce the on-resistance of the semiconductor devices
Data Source
AI summary
A semiconductor device of an embodiment includes: a nitride semiconductor layer including a first GaN region of n-type, a second GaN region of n-type on the first GaN region, a third GaN region of p-type on the first GaN region, a fourth GaN region of p-type sandwiching the second GaN region with the third GaN region, a fifth GaN region of p-type on the third GaN region, a sixth GaN region of p-type sandwiching the second GaN region with the fifth GaN region, a seventh GaN region of n-type on the fifth GaN region, an eighth GaN region of n-type on the sixth GaN region, a trench between the seventh GaN region and the eighth GaN region, the trench having an inclination angle of less than 90 degrees; a gate insulating layer including an aluminum nitride film in the trench; a gate electrode; a first electrode; and a second electrode.