Semiconductor Trench Layout for Gate Insulation Avalanche Protection

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Solution Overview

Problem

Existing semiconductor devices face challenges in achieving improved static and dynamic behavior, particularly in withstanding high voltages and currents while protecting gate insulation layers from avalanches during switching events.

Innovation Solution

The semiconductor device design includes a semiconductor body with a drift region and multiple base regions, featuring first and second-type trenches with specific electrical insulation and conductive material configurations, along with contact areas to manage charge carrier extraction and reduce avalanche intensity, ensuring the gate insulation layer's protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a gate electrode is placed in a trench to control the semiconductor device, then the device can be switched on and off, but the gate insulation layer in the trench is vulnerable to avalanche damage during switching events

Engineering Contradiction:
Improveswitching capabilityVSAvoidgate insulation layer protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The semiconductor device is divided into multiple independent cells, each with its own trench structure. By segmenting the device into first-type cells (with gate electrodes) and second-type cells (without gate electrodes), the avalanche energy is distributed and prevented from concentrating on a single gate insulation layer, thus protecting the gate structure while maintaining switching capability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Second-type trenches are introduced as intermediary structures between first-type trenches containing gate electrodes. These second-type trenches act as buffer zones that intercept and dissipate avalanche energy before it can reach the gate insulation layer in adjacent first-type trenches, thereby protecting the gate structure from damage

Inventive Principle:
Principle #24Intermediary (Mediator)

2Power

If the semiconductor device is designed to handle high voltages and currents, then the power handling capability is improved, but the risk of avalanche damage to the gate insulation layer increases

Engineering Contradiction:
Improvepower handling capabilityVSAvoidavalanche damage risk
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful avalanche effect into a beneficial protective mechanism by strategically placing second-type trenches that intentionally attract and dissipate avalanche energy. The controlled avalanche occurrence in second-type trenches protects the gate insulation layers in first-type trenches, transforming a harmful phenomenon into a protective feature that enables high power operation

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Different regions of the semiconductor device are assigned different functions: first-type trenches contain gate electrodes for switching control, while second-type trenches are designed to be avalanche-resistant zones. This local differentiation allows the device to handle high voltages and currents by confining avalanche damage to specific protected regions while maintaining gate integrity in other regions

Inventive Principle:
Principle #3Local quality

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 design enhances the semiconductor device's ability to handle high voltages and currents while minimizing damage to the gate insulation layer during switching events, improving both static and dynamic performance and extending the device's operational stability.

Implementation Method 1

The gate electrode is separated from the semiconductor body by a gate insulation layer

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

contact areas to manage charge carrier extraction and reduce avalanche intensity

Methodology Applied
Scientific EffectCharge carrier extraction: Electrical Resistance

Implementation Method 3

protect the first-type trench, particularly the gate insulation layer therein, for example from avalanches during switching events

Methodology Applied
Scientific EffectAvalanche breakdown: Avalanche Breakdown

Data Source

PatentEP4394889A1Semiconductor device and method for producing a semiconductor device
Publication Date: 2024.07.03 HITACHI ENERGY LTD
  • EP4394889A1 patent drawingFigure 1~2
  • EP4394889A1 patent drawingFigure 3~4
  • EP4394889A1 patent drawingFigure 5~6

AI summary

The semiconductor device (100) comprises a semiconductor body (10) with a top side (11) and a bottom side (19). A first main electrode (2) is arranged on the top side and a second main electrode (3) is arranged on the bottom side. The semiconductor device comprises a gate electrode (4) and at least two trenches, namely a first-type trench (51) and a second-type trench (52). The semiconductor body comprises a drift region (14) of a first conductivity type and at least three base regions (13a, 13b, 13c) each of a second conductivity type. The semiconductor body further comprises an injection region (12) of the first conductivity type. The first main electrode is in electrical contact with the injection region. The gate electrode extends into the first-type trench. The second-type trench is free of the gate electrode. The third base region comprises at least one contact area (6c) in which the third base region is in electrical contact with an electrode of the semiconductor device which is different from the gate electrode.