Vertical Semiconductor Trench Isolation for Active Area Recovery

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Solution Overview

Problem

Existing vertical semiconductor devices face challenges with large area occupation by field termination, increased manufacturing costs, and thermal budget due to complex processing requirements for field termination in reverse bias operations.

Innovation Solution

A vertical semiconductor device design featuring a trench that electrically isolates the second semiconductor region, reducing the area required for field termination and simplifying the manufacturing process by eliminating the need for complex layer structuring and ion implantation steps, allowing the second semiconductor region to fully cover the first semiconductor region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the field termination area is increased to prevent premature lateral breakdown, then the reliability is improved, but the active area of the semiconductor device is reduced

Engineering Contradiction:

Improveprevention of premature lateral breakdownVSAvoidactive area of semiconductor device

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The second semiconductor region is segmented into an inner portion and an outer portion by introducing a trench structure. This segmentation allows the outer portion to provide field termination functionality while the inner portion maintains active device area, thus preventing premature lateral breakdown without sacrificing active area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a two-dimensional planar structure to a three-dimensional structure by introducing a trench that extends vertically through the semiconductor layers. This vertical dimensionality change enables electrical isolation between the inner and outer portions of the second semiconductor region, allowing field termination without occupying lateral active area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If complex processing steps including mask layer, lithography, etching, and ion implantation are used to form the second semiconductor region, then the manufacturing precision is improved, but the manufacturing cost and thermal budget are increased

Engineering Contradiction:

Improveformation of second semiconductor regionVSAvoidmanufacturing cost and thermal budget

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention extracts and removes the trench structure after formation, eliminating the need for complex mask layer, lithography, and etching steps to define the second semiconductor region. This extraction approach simplifies the manufacturing process while maintaining the ability to form the second semiconductor region with appropriate precision through alternative methods.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using complex processing steps to directly form the second semiconductor region with precise boundaries, the invention inverts the approach by first forming a continuous second semiconductor region and then using a trench to define the inner and outer portions. This inversion simplifies the manufacturing process by eliminating multiple complex steps.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the second semiconductor region is structured into the epitaxial layer with specific distances from substrate and edge, then the reliability is improved, but the device complexity is increased

Engineering Contradiction:

Improvefield termination performanceVSAvoidstructuring of second semiconductor region

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The second semiconductor region is segmented into inner and outer portions by a trench, simplifying the overall device structure. The outer portion provides field termination while the inner portion maintains active functionality, achieving reliable field termination without complex structuring of the entire second semiconductor region.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The trench acts as an intermediary structure that electrically isolates the inner and outer portions of the second semiconductor region. This intermediary element simplifies the device structure by providing clear electrical separation without requiring complex structuring or multiple layers to achieve the same isolation effect.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240072113A1Vertical semiconductor device and manufacturing method therefor

Publication Date: 2024.02.29 NEXPERIA BV

AI summary

A vertical semiconductor device and method for manufacturing the same is provided. The semiconductor device includes a body with a substrate and an epitaxial layer on the substrate, the layer includes a first region of a first conductivity type, and a second region of a second different conductivity type, the second region is arranged opposite to the substrate with respect to the first region, and when viewed in a first direction from the layer to the substrate, the first region and the second region each extend across an entire area of the body. The device further includes a trench arranged in the body, extending through the second region and at least partially into the first region, thereby dividing the second region into an inner and an outer portion that are mutually electrically isolated, and a first conductive contact on the second region to enable electrically accessing the inner portion.