SiC Trench MOSFET Gate Layout to Reduce Trench-End Field Stress
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Solution Overview
Problem
The reliability of the gate insulating layer in silicon carbide (SiC) MOSFETs with a trench gate structure is compromised due to electric field concentration at the trench ends, leading to reduced reliability and increased leakage current.
Innovation Solution
The design incorporates a trench gate structure where the gate electrode and wiring are not present between the end of the trench and the interlayer insulating layer, alleviating electric field concentration and enhancing the reliability of the gate insulating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the gate electrode is drawn to the outside of the trench by gate wiring, then the gate voltage can be applied, but electric field concentrates on the gate insulating layer at the end of the trench, reducing reliability
Solution Approach 1:
The gate electrode is extracted from the trench structure and extended outward as gate wiring that can be drawn to the outside of the trench. This allows gate voltage application while removing the electrode from the high-stress trench environment, thereby preventing electric field concentration on the gate insulating layer at the trench end and improving reliability
Solution Approach 2:
The gate wiring acts as an intermediary between the gate electrode inside the trench and the external voltage source. By providing this intermediate conductive path, the system can apply gate voltage without requiring the electrode itself to be exposed, thus maintaining electrical functionality while protecting the gate insulating layer from electric field concentration
2Loss of energy
If the trench gate structure is applied to increase channel area, then on-resistance is reduced, but electric field concentration occurs at the trench end
Solution Approach 1:
The gate electrode is extracted from the trench and extended outward as wiring. This maintains the trench gate structure's benefit of increased channel area and reduced on-resistance, while simultaneously removing the electrode from the trench end where electric field concentration occurs, thereby eliminating the harmful effect
Solution Approach 2:
The gate electrode is extended from the vertical dimension (inside the trench) to the horizontal dimension (outside the trench as wiring). This dimensional transition allows the electrode to maintain its functional role in creating the channel while avoiding the electric field concentration problem at the trench end
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 improves the reliability of the gate insulating layer by reducing electric field-induced leakage current, thereby enhancing the overall performance and longevity of the MOSFET.
Implementation Method 1
an electric field may concentrate on a gate insulating layer at an end of the trench
Data Source
AI summary
A semiconductor device according to an embodiment includes: a silicon carbide layer having a first plane parallel to a first direction and a second direction orthogonal to the first direction, and a second plane facing the first plane, the silicon carbide layer including a first trench and a second trench extending in the first direction; a gate electrode in the first trench and the second trench; a gate insulating layer; a gate wiring extending in the second direction, intersecting with the first trench and the second trench, connected to the gate electrode; a first electrode; a second electrode; and an interlayer insulating layer provided between the gate electrode and the first electrode. Neither the gate electrode nor the gate wiring is present between an end of the first trench in the first direction and the interlayer insulating layer.