SiC Trench Device Extension Zone Shields Gate Dielectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon Carbide (SiC) trench semiconductor devices face challenges in meeting reliability demands for gate dielectrics due to high breakdown electric fields, requiring innovative designs to enhance device performance.
Innovation Solution
The design includes a silicon carbide semiconductor body with a trench structure featuring a gate dielectric and gate electrode, along with specific doping zones such as a body zone, extension zone, and drift zone, which are electrically coupled to improve the reliability of the gate dielectric and reduce electric field stress, thereby enhancing the device's operational reliability and on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a conventional trench structure with gate dielectric is used in SiC semiconductor devices, then the device can operate at high voltage levels, but the gate dielectric reliability deteriorates due to high breakdown electric fields
Solution Approach 1:
An extension zone of the first conductivity type is introduced as an intermediary region between the body zone and the drift zone. This extension zone acts as a mediator that gradually transitions the dopant concentration from the high-doped body zone to the low-doped drift zone, thereby reducing the abrupt electric field changes that stress the gate dielectric. The extension zone with intermediate dopant concentration levels serves as a buffer region that protects the gate dielectric from direct exposure to high breakdown electric fields.
Solution Approach 2:
The patent applies local quality by creating distinct zones with different dopant concentrations: the body zone with high dopant concentration for low on-resistance, the drift zone with low dopant concentration for high voltage blocking, and the extension zone with intermediate dopant concentration specifically positioned to reduce electric field stress on the gate dielectric. Each zone has optimized local properties tailored to its specific function, with the extension zone locally addressing the gate dielectric reliability issue.
2Reliability
If the dopant concentration in the body zone is increased to reduce on-resistance, then the on-resistance decreases, but the electric field stress on the gate dielectric increases
Solution Approach 1:
The semiconductor device is segmented into multiple distinct zones along the vertical direction: the body zone, the extension zone, and the drift zone. This segmentation allows the high dopant concentration to be confined to the body zone for low on-resistance, while the extension zone and drift zone gradually transition to lower dopant concentrations to reduce electric field stress on the gate dielectric. The segmentation creates a graded structure that decouples the conflicting requirements of low on-resistance and low electric field stress.
Solution Approach 2:
The patent employs parameter changes by varying the dopant concentration parameter through the vertical structure. The body zone has high dopant concentration for low on-resistance, the extension zone has intermediate dopant concentration to reduce electric field stress, and the drift zone has low dopant concentration for high voltage blocking. This gradual parameter change in dopant concentration creates a graded junction that reduces abrupt electric field changes and minimizes stress on the gate dielectric while maintaining low 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 proposed design improves the reliability of the gate dielectric and reduces on-resistance by creating a space charge region that shields the dielectric from high electric fields, leading to superior performance in high-voltage operations.
Implementation Method 1
creating a space charge region that shields the dielectric from high electric fields
Implementation Method 2
A body zone of a first conductivity type adjoins to a sidewall of the trench, the body zone being electrically coupled to a contact via a body contact zone including a higher maximum concentration of dopants than the body zone
Data Source
AI summary
A semiconductor device as described herein includes a silicon carbide semiconductor body. A trench extends into the silicon carbide semiconductor body at a first surface. A gate dielectric and a gate electrode are formed within the trench. A body zone of a first conductivity type adjoins to a sidewall of the trench, the body zone being electrically coupled to a contact via a body contact zone including a higher maximum concentration of dopants than the body zone. An extension zone of the first conductivity type is electrically coupled to the contact via the body zone, wherein a maximum concentration of dopants of the extension zone along a vertical direction perpendicular to the first surface is higher than the maximum concentration of dopants of the body zone along the vertical direction. A distance between the first surface and a bottom side of the extension zone is larger than the distance between the first surface and the bottom side of the trench.