Schottky Barrier Diode Reverse Surge Withstand Capability

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Solution Overview

Problem

Conventional Schottky barrier diodes face challenges in maintaining reverse surge withstand capability due to excessive reverse voltage exceeding breakdown voltage limits, leading to potential deterioration of diode characteristics.

Innovation Solution

The semiconductor device incorporates a semiconductor substrate with a first conductive type and a second portion of opposite conductivity type, where the side and bottom surfaces of the second portion are in contact with the first portion, and the bottom surface of the second portion is positioned lower than the main surface, reducing resistance and enhancing surge current flow to the Schottky junction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a conventional Schottky barrier diode structure is used, then the diode operates at high speed with small forward voltage drop, but the reverse surge withstand capability is poor when emergency stop is performed

Engineering Contradiction:

Improveoperating speedVSAvoidreverse surge withstand capability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The diode structure is segmented into multiple functional regions: a first concentration portion (p+) and a second concentration portion (p-) with different impurity concentrations, arranged in a specific spatial configuration. This segmentation allows different regions to handle different aspects of the electrical stress, with the first concentration portion providing low resistance paths and the second concentration portion providing field control, thereby improving reverse surge withstand capability while maintaining high-speed operation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the diode are assigned different local properties: the first concentration portion has high impurity concentration for low resistance, while the second concentration portion has lower impurity concentration for field control. The metal layer is positioned to contact specific regions at different depths, creating local variations in electrical characteristics that optimize both speed and reliability

Inventive Principle:

Principle #3Local quality

2Reliability

If the reverse voltage exceeds the breakdown voltage limit, then the diode characteristics deteriorate, but reducing the breakdown voltage limit would reduce the operating voltage range

Engineering Contradiction:

Improvediode characteristic stabilityVSAvoidreverse voltage tolerance

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The diode structure incorporates protective elements in advance: the specific arrangement of the first and second concentration portions creates a gradual field distribution that cushions the impact of reverse voltage surges before they can cause breakdown. This preemptive field management prevents sudden characteristic deterioration while maintaining high reverse voltage tolerance

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The invention changes the impurity concentration parameter spatially, creating a gradient from the first concentration portion (high concentration) to the second concentration portion (lower concentration). This parameter variation allows the diode to maintain stable characteristics across a wide reverse voltage range by controlling the electric field distribution to prevent premature breakdown

Inventive Principle:

Principle #35Parameter changes

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 reduces the resistance value at the Schottky junction, allowing for improved reverse surge withstand capability and preventing functional deterioration even under excessive reverse voltage conditions.

Implementation Method 1

A diode, which is an example of a semiconductor device, such as a Schottky barrier diode (hereinafter, occasionally referred to as an SBD), is a semiconductor device using rectifying action of a Schottky barrier at a Schottky junction between a semiconductor layer and a metal layer

Methodology Applied

Scientific EffectSchottky barrier rectifying action:

Implementation Method 2

a Schottky barrier diode (hereinafter, occasionally referred to as an SBD), is a semiconductor device using rectifying action of a Schottky barrier at a Schottky junction between a semiconductor layer and a metal layer

Methodology Applied

Scientific EffectSchottky barrier effect:

Data Source

PatentUS9653539B2Semiconductor device

Publication Date: 2017.05.16 SHINDENGEN ELECTRIC MANUFACTURING CO LTD

AI summary

It is an objective to improve reverse surge withstand capability of a semiconductor device, for example, a Schottky barrier diode.A p-type semiconductor section 14 includes a p+ type semiconductor portion (first concentration portion) 14a and a p− type semiconductor portion (second concentration portion) 14b, which have different impurity concentrations from each other. Additionally, a part of a side surface 13S of a metal portion 13 and a part of a bottom surface 13B of the metal portion 13 connected to the side surface 13S thereof are in contact with a part of the p+ type semiconductor portion 14a. Further, at least a part of a side surface 14bS of the p− type semiconductor portion 14b is in contact with a side surface 14aS of the p+ type semiconductor portion 14a.