JBS Diode Drift Region Segmentation for Leakage Control

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Solution Overview

Problem

JBS diodes with low barrier height suffer from high leakage currents under high reverse bias voltages due to increased electrical fields, which is not adequately mitigated by reducing the distance between implanted regions, leading to performance deterioration.

Innovation Solution

The design incorporates a drift region with a doping profile that includes both superficial and deep implanted regions, with the deep implanted regions being staggered and having a higher doping level, forming depleted areas that reduce the electrical field, and ohmic-contact regions to manage the Schottky junctions, allowing for low leakage currents and efficient current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the barrier height of Schottky junctions is reduced to enable low forward voltage, then the switch-on threshold voltage decreases and energy consumption is reduced, but leakage current increases significantly under high reverse bias voltages

Engineering Contradiction:

Improveenergy consumptionVSAvoidleakage current

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The drift region is segmented into multiple regions with different doping levels: a first drift region with lower doping level and a second drift region with higher doping level. This segmentation allows the low-doping region to support high reverse bias voltages with low leakage current, while the high-doping region enables low forward voltage operation, thus resolving the contradiction between low energy consumption and low leakage current.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the drift region are assigned different doping qualities: the first drift region (contacting Schottky junctions) has lower doping level optimized for low forward voltage, while the second drift region (between implanted regions) has higher doping level optimized for low leakage current. This local quality differentiation allows each region to optimize its function, resolving the contradiction between energy efficiency and leakage suppression.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If the distance between implanted regions is reduced to lower electrical field and mitigate leakage current, then leakage current decreases, but the area available for current flow in forward bias is reduced, increasing resistance

Engineering Contradiction:

Improveleakage currentVSAvoidforward conduction performance

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The drift region is divided into a first drift region with lower doping level that provides large area for current flow (reducing resistance), and a second drift region with higher doping level that suppresses leakage current. This segmentation allows the device to achieve both low resistance in forward bias and low leakage current in reverse bias, resolving the contradiction between forward conduction performance and leakage current suppression.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The doping level parameter is changed spatially within the drift region: lower doping level in the first drift region to reduce resistance and improve forward conduction, and higher doping level in the second drift region to reduce leakage current. This parameter change resolves the contradiction between forward performance and leakage suppression by optimizing each region for its specific function.

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 achieves low leakage currents under high reverse bias and enables high operating current with low forward voltage, improving the overall performance and energy efficiency of the JBS diode.

Implementation Method 1

The deep implanted regions are staggered and have a higher doping level, forming depleted areas that reduce the electrical field

Methodology Applied

Scientific EffectDepleted region formation:

Implementation Method 2

Portions of the anode metallization region in direct electrical contact with the drift region, alongside the implanted regions, form Schottky junctions (i.e. semiconductor-metal junctions)

Methodology Applied

Scientific EffectSchottky barrier formation:

Data Source

PatentEP4040498A1Vertical conduction electronic device comprising a JBS diode and manufacturing process thereof

Publication Date: 2022.08.10 STMICROELECTRONICS SRL

Figure 1~2A
Figure 2~3
Figure 4~6

AI summary

The vertical conduction electronic device (50) is formed by a body (55) of wide-bandgap semiconductor material having a first conductivity type and a surface (55A), which defines a first direction (Y) and a second direction (X), wherein the body has a drift region (59, 59A, 59B). The electronic device is further formed by a plurality of superficial implanted regions (62) having a second conductivity type, which extend in the drift region from the surface and delimit between them, in the drift region, at least one superficial portion (68) facing the surface; by at least one deep implanted region (65) having the second conductivity type, which extends in the drift region, at a distance from the surface of the body; and by a metal region (80), which extends on the surface of the body, in Schottky contact with the superficial portion (68) of the drift region.