Orthogonal Trench Alignment in Semiconductor Devices

Solution Overview

Problem

Conventional semiconductor devices, such as IGBTs, face challenges in suppressing leakage current and optimizing the trade-off between ON voltage and turn-off loss due to the alignment of trench portions in transistor and diode portions.

Innovation Solution

The semiconductor device incorporates trench portions in transistor and diode portions with orthogonal directions, along with a lifetime control region and well regions, to reduce electric field concentration and injection of holes, thereby improving reverse recovery characteristics and suppressing leakage current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If trench portions in transistor portions and diode portions are aligned in the same direction, then manufacturing is simplified, but leakage current increases and reverse recovery characteristics deteriorate

Engineering Contradiction:

Improvetrench alignment simplicityVSAvoidleakage current suppression

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by intentionally misaligning the trench portions in transistor portions and diode portions. Specifically, the trench portions in transistor portions extend in a first direction while trench portions in diode portions extend in a second direction that is different from the first direction. This asymmetric arrangement prevents direct alignment between transistor and diode trenches, reducing electric field concentration at interfaces and suppressing leakage current, thereby improving reverse recovery characteristics without significantly complicating manufacturing.

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If trench portions in transistor portions and diode portions are aligned in the same direction, then manufacturing is simplified, but reverse recovery characteristics deteriorate

Engineering Contradiction:

Improvetrench alignment simplicityVSAvoidreverse recovery characteristics

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies asymmetry by intentionally misaligning the trench portions in transistor portions and diode portions. Specifically, the trench portions in transistor portions extend in a first direction while trench portions in diode portions extend in a second direction that is different from the first direction. This asymmetric arrangement prevents direct alignment between transistor and diode trenches, reducing electric field concentration at interfaces and suppressing leakage current, thereby improving reverse recovery characteristics without significantly complicating manufacturing.

Inventive Principle:

Principle #4Asymmetry

3Device complexity

If conventional trench alignment is used, then device structure is simple, but electric field concentration increases causing higher leakage current

Engineering Contradiction:

Improvetrench arrangement complexityVSAvoidelectric field concentration

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent applies asymmetry by intentionally misaligning the trench portions in transistor portions and diode portions. Specifically, the trench portions in transistor portions extend in a first direction while trench portions in diode portions extend in a second direction that is different from the first direction. This asymmetric arrangement prevents direct alignment between transistor and diode trenches, reducing electric field concentration at interfaces and suppressing leakage current, thereby improving reverse recovery characteristics without significantly complicating manufacturing.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS10643992B2Semiconductor device

Publication Date: 2020.05.05 FUJI ELECTRIC CO LTD

AI summary

A semiconductor device is provided, the semiconductor device including: a semiconductor substrate having a first-conductivity-type drift region; one or more transistor portions provided in the semiconductor substrate; and one or more diode portions provided in the semiconductor substrate, wherein both the transistor portions and the diode portions have trench portions that lie from a top surface of the semiconductor substrate to the drift region and include conductive portions, and in a top view of the semiconductor substrate, a main direction of the trench portions in the transistor portions is different from a main direction of the trench portions in the diode portions.