IGBT Branched Gate Trench Electric Field Management

Solution Overview

Problem

Conventional semiconductor devices with branched gate trenches face challenges in optimizing trench depth and distribution, leading to electric field concentration and avalanche breakdown, which affects breakdown voltage and threshold voltage variability.

Innovation Solution

The semiconductor device incorporates a first trench portion with a branch portion surrounded by a contact region, a second trench portion as a dummy trench, and an accumulation region, with specific insulating films and conductive portions to control channel formation and electric field distribution, allowing for adjustable trench density and reduced latch-up and threshold voltage variation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gate trench is formed at a deeper position at the branch portion, then the trench can surround operating regions more effectively, but electric field concentration occurs leading to avalanche breakdown

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by forming an accumulation region with higher impurity concentration at the branch portion of the gate trench. This localized modification of material properties (impurity concentration) specifically addresses the electric field concentration problem at the critical branch portion without changing the overall trench structure, thereby preventing avalanche breakdown while maintaining effective region surrounding.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the gate trench is formed at a deeper position at the branch portion, then the trench density can be adjusted, but threshold voltage variability increases

Engineering Contradiction:

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent introduces local quality through the accumulation region that is selectively formed at branch portions. This allows different structural characteristics at different locations (deeper trench at branch vs. standard trench elsewhere) while maintaining uniform threshold voltage through the localized impurity concentration adjustment that compensates for the structural variations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies parameter changes by modifying the impurity concentration parameter locally at the branch portion through the accumulation region. This parameter modification (higher impurity concentration) compensates for the structural difference of the deeper trench, thereby maintaining uniform electrical characteristics across different trench locations while allowing trench density adjustment.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the branch portion is surrounded by contact region, then latch-up can be suppressed, but the device complexity increases

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies merging by combining the contact region formation with the branch portion structure. The contact region is integrated into the design to surround the branch portion, achieving dual functionality: it provides electrical contact and simultaneously suppresses latch-up by controlling the electric field distribution at the branch portion.

Inventive Principle:

Principle #5Merging (Combining)

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 enhances breakdown voltage, suppresses latch-up, and reduces threshold voltage variation by efficiently managing electric fields and current flow, improving the overall performance and reliability of the semiconductor device.

Implementation Method 1

The gate trench portion may include an insulating film formed on an inner wall of a gate trench provided extending from the front surface of the semiconductor substrate and penetrating the base region

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

an accumulation region with a higher impurity concentration than the drift region is provided between the gate trench portion and the drift region

Methodology Applied

Scientific EffectImpurity concentration:

Implementation Method 3

Conventional semiconductor devices with branched gate trenches face challenges in optimizing trench depth and distribution, leading to electric field concentration and avalanche breakdown

Methodology Applied

Scientific EffectAvalanche breakdown: Avalanche Breakdown

Data Source

PatentUS10818782B2Insulated-gate bipolar transistor (IGBT) including a branched gate trench

Publication Date: 2020.10.27

AI summary

At a portion at which a gate trench is branched, the trench is formed at a deeper position than at portions of the gate trench having a linear shape. A semiconductor device is provided, including: a first conductivity-type semiconductor substrate; a second conductivity-type base region provided at a front surface side of the semiconductor substrate; a first trench portion provided extending from a front surface of the semiconductor substrate and penetrating the base region; and a second conductivity-type contact region which is provided in a part of the base region at a front surface side of the semiconductor substrate and has a higher impurity concentration than the base region, wherein the first trench portion has a branch portion on the front surface of the semiconductor substrate, and the branch portion is provided being surrounded by the contact region on the front surface of the semiconductor substrate.