SiC Gate Trench Layout for Lower Feedback Capacitance
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Solution Overview
Problem
Conventional silicon carbide semiconductor devices with electric field shielding regions experience high feedback capacity and significant switching loss due to blocked conduction between the source electrode and the field shielding region.
Innovation Solution
The silicon carbide semiconductor device incorporates a silicon carbide substrate with specific conductive regions and a gate trench structure, where the contact region and electric field relaxation region are electrically connected, reducing feedback capacity and switching loss by enhancing carrier supply and depletion layer action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electric field shielding region is provided below a gate trench in conventional silicon carbide semiconductor devices, then the electric field shielding effect is achieved, but the conduction between source electrode and field shielding region is blocked causing high feedback capacity and significant switching loss
Solution Approach 1:
The patent segments the semiconductor device structure by introducing a gate trench that divides the drift region into multiple regions. This segmentation allows the electric field shielding region to be positioned below the gate trench while maintaining conduction paths through the drift region, thereby resolving the contradiction between achieving electric field shielding and maintaining low switching loss.
Solution Approach 2:
The drift region acts as an intermediary that connects the source electrode to the electric field shielding region. By maintaining the drift region's continuity and optimizing its doping concentration, the patent enables electrical conduction between the source electrode and field shielding region while the gate trench provides the necessary electric field shielding effect, thus reducing both feedback capacity and switching loss.
2Reliability
If the gate trench penetrates the source region and body region to reach the drift region, then the electric field shielding is enhanced, but the device complexity increases
Solution Approach 1:
The gate trench structure serves multiple functions simultaneously: it provides electric field shielding, defines the channel region, and enables controlled conduction paths through the drift region. This multi-functionality reduces the need for additional separate structures, thereby enhancing electric field shielding while limiting the increase in device complexity.
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 effectively reduces feedback capacity and switching loss, improving switching speed and ensuring sufficient current flow during operation.
Implementation Method 1
a connection region that is the second conductive type, the connection region electrically connecting the contact region to the electric field relaxation region
Implementation Method 2
enhancing carrier supply and depletion layer action
Implementation Method 3
enhancing carrier supply and depletion layer action
Data Source
AI summary
A silicon carbide semiconductor device includes a silicon carbide substrate having a first main surface and a second main surface opposite to the first main surface. A gate trench is provided in the first main surface. The gate trench is defined by side surfaces and a bottom surface. The side surfaces penetrate the source region and the body region to reach the drift region. The bottom surface connects to the side surfaces. The gate trench extends in a first direction parallel to the first main surface. The silicon carbide substrate further includes an electric field relaxation region that is the second conductive type, the electric field relaxation region being provided between the bottom surface and the second main surface and extending in the first direction, and a connection region that is the second conductive type, the connection region electrically connecting a contact region to the electric field relaxation region. In a plan view in a direction normal to the first main surface, the gate trench and the electric field relaxation region are disposed on a virtual line that extends in the first direction, and the connection region is in contact with the electric field relaxation region on the virtual line.