Semiconductor Terminal Structure for Leakage Suppression

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Solution Overview

Problem

Existing power semiconductor devices face high leakage current and increased heat generation due to large energy loss, primarily because the depletion layer extends to the end of the semiconductor substrate, creating a low resistance region that increases leakage paths.

Innovation Solution

The semiconductor device incorporates a P− layer separated from the N++ layer in the terminal portion, with an electrode connected to the N++ layer via an insulating film, preventing contact between the P− layer and the low resistance region, and using a polycrystalline semiconductor film to generate an N-type accumulation layer, reducing leakage current and heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the depletion layer extends to the end of the semiconductor substrate to increase breakdown voltage, then the withstand voltage is improved, but the leakage current increases and heat generation increases

Engineering Contradiction:

Improvewithstand voltageVSAvoidleakage current and heat generation

Core Design Contradiction:

StrengthVSLoss of energy

Solution Approach 1:

The terminal portion is divided into multiple impurity layers (first impurity layer, second impurity layer, third impurity layer, fourth impurity layer) with different conductivity types and concentrations. This segmentation creates multiple depletion regions that collectively suppress leakage current while maintaining high withstand voltage capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the terminal portion are assigned different impurity concentrations and conductivity types. The first impurity layer has high concentration at the end portion, the second impurity layers have intermediate concentration in intermediate portions, and the third and fourth impurity layers have low concentration in specific regions. This local quality variation optimizes both breakdown voltage and leakage current suppression in different areas.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If multiple impurity layers are disposed in the terminal portion to suppress leakage current, then the leakage current is reduced, but the device complexity increases

Engineering Contradiction:

Improveleakage currentVSAvoidstructure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

Multiple impurity layers with different functions are merged into a single integrated structure in the terminal portion. The first, second, third, and fourth impurity layers are combined to simultaneously achieve leakage current suppression, heat generation reduction, and high breakdown voltage, rather than using separate structures for each function.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The terminal portion structure serves multiple functions: the first impurity layer provides high concentration doping for voltage blocking, the second impurity layers provide intermediate concentration for transition, and the third and fourth impurity layers provide low concentration for leakage suppression. This multi-functional design achieves multiple objectives within a single integrated structure.

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 effectively suppresses leakage current and heat generation, allowing for higher withstand voltage and reduced energy loss by preventing leakage paths and electric field concentration, while maintaining a reduced semiconductor substrate size for cost-effectiveness.

Implementation Method 1

an insulating film disposed on at least a part of the terminal portion, the insulating film having a first opening on the first impurity layer; and an electrode disposed on the insulating film, the electrode connected to the first impurity layer via the first opening

Methodology Applied

Scientific EffectPhysical separation through insulating film: Physical Containment

Implementation Method 2

The leakage current of the semiconductor device can be reduced... since the leakage current is relatively large, the heat generated in the off state of the semiconductor device is increased

Methodology Applied

Scientific EffectDepletion layer formation: Electric Field

Data Source

PatentUS11004932B2Semiconductor device

Publication Date: 2021.05.11 MITSUBISHI ELECTRIC CORP

AI summary

The semiconductor device includes: a fourth impurity layer disposed in a state of being connected to the outermost peripheral second impurity layer and being separated from the first impurity layer between the outermost peripheral second impurity layer and the first impurity layer of the terminal portion, the fourth impurity layer having a second conductivity type and having an impurity concentration lower than an impurity concentration of the second impurity layer; an insulating film disposed on at least a part of the terminal portion, the insulating film having a first opening on the first impurity layer; and an electrode disposed on the insulating film, the electrode connected to the first impurity layer via the first opening.