Back Side Metal Structure for Reverse Blocking

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Solution Overview

Problem

Conventional semiconductor devices face challenges in achieving enhanced reverse blocking capabilities, as existing edge termination constructions often result in reduced reverse breakdown voltage and increased leakage current due to inefficient field shaping and dopant concentration distribution.

Innovation Solution

The semiconductor device incorporates a field shaping zone with a maximum dopant concentration at least three times higher than the base layer, combined with a dielectric structure and a back side metal structure, which effectively concentrates the electric field within the dielectric, reducing leakage current and improving reverse blocking characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional edge termination constructions are used, then manufacturing is simpler, but reverse blocking capability is reduced and leakage current increases

Engineering Contradiction:

Improvereverse blocking capabilityVSAvoidedge termination construction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The edge termination construction is segmented into distinct functional zones: a field shaping zone with high dopant concentration for electric field concentration, a dielectric structure for field termination, and a back side metal structure for potential distribution. This segmentation allows each zone to perform its specific function optimally, achieving enhanced reverse blocking capability while managing complexity through functional specialization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating a field shaping zone with dopant concentration at least three times higher than the base layer, specifically in the edge portion. This localized high doping region concentrates the electric field where needed, while the dielectric structure provides localized field termination. The back side metal structure extends specifically into the edge portion to provide localized potential distribution, thereby improving reverse blocking capability without requiring uniform complexity throughout the entire device.

Inventive Principle:

Principle #3Local quality

2Reliability

If field shaping zone with high dopant concentration is implemented, then reverse blocking capability is enhanced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvereverse blocking capabilityVSAvoiddopant concentration control precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent specifies a quantitative parameter relationship: the maximum dopant concentration in the field shaping zone must exceed at least three times the maximum dopant concentration in the base layer. This parameter change provides a clear manufacturing target and acceptance criterion, enabling consistent achievement of the desired electric field concentration effect while providing measurable guidance for process control and quality assurance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If back side metal structure extends into edge portion, then electric field distribution is improved, but device complexity increases

Engineering Contradiction:

Improveelectric field distributionVSAvoidmetal structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The back side metal structure serves multiple functions: it provides the primary electrical contact on the back side, extends into the edge portion to distribute potential and improve electric field distribution, and works in conjunction with the dielectric structure to support the field termination function. This multi-functionality reduces the need for additional separate structures, thereby improving electric field distribution without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 the reverse blocking capability by minimizing leakage current and maintaining effective transistor gain, while reducing surface generation current and improving area efficiency.

Implementation Method 1

a field shaping zone with a maximum dopant concentration that exceeds at least three times a maximum dopant concentration in the base layer... effectively concentrates the electric field within the dielectric

Methodology Applied

Scientific EffectElectric field concentration: Electric Field

Implementation Method 2

A dielectric structure is between the back side metal structure and the field shaping zone... minimizing leakage current

Methodology Applied

Scientific EffectDielectric isolation: Dielectric

Data Source

PatentUS8618576B1Semiconductor device with back side metal structure

Publication Date: 2013.12.31 INFINEON TECHNOLOGIES AG

AI summary

A semiconductor device includes a semiconductor body with a base layer and a field shaping zone of a first conductivity type. The base layer extends parallel to a back surface of the semiconductor body in a central portion and into an edge portion that surrounds the central portion. The field shaping zone is formed in the edge portion and has a maximum dopant concentration exceeding at least three times a maximum dopant concentration in the base layer. A back side metal structure directly adjoins the back surface in the central portion and extends over the edge portion. A dielectric structure is between the back side metal structure and the field shaping zone. Leakage current mechanisms reducing the reverse blocking capabilities are reduced.