RC-IGBT Diode Region Direct Contact Structure

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Solution Overview

Problem

Conventional reverse conducting IGBTs face challenges in achieving favorable diode characteristics and low manufacturing costs due to high contact resistance between the p-type anode layer and barrier metal, and the need for different process conditions for IGBT and diode regions, which increases complexity and cost.

Innovation Solution

The semiconductor device eliminates the need for a high concentration p+-type anode layer in the diode region by directly contacting the first electrode with the semiconductor layer in the diode region, eliminating the barrier metal and tungsten plug, allowing for shared electrode conditions between IGBT and diode regions, thus reducing contact resistance and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If barrier metal and tungsten plug are used in diode region to reduce contact resistance, then contact resistance decreases, but manufacturing cost increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent divides the semiconductor device into distinct IGBT region and diode region, applying different structural configurations to each region. The IGBT region uses barrier metal and tungsten plug, while the diode region uses direct connection, segmenting the solution to optimize for each specific functional requirement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different structural qualities to different regions: the IGBT region has barrier metal and tungsten plug for low contact resistance, while the diode region has direct connection between aluminum electrode and p-type anode layer. This local differentiation optimizes each region for its specific electrical characteristics and manufacturing requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

If different electrode materials are used in IGBT and diode regions, then region-specific performance is optimized, but assembly process complexity increases

Engineering Contradiction:

Improveregion-specific performanceVSAvoidassembly process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the device into IGBT region and diode region with different electrode configurations. The IGBT region uses aluminum electrode with barrier metal and tungsten plug, while the diode region uses direct aluminum electrode connection, allowing each region to be optimized independently while maintaining overall device functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different electrode material configurations are applied locally to different regions based on their specific performance requirements. The IGBT region uses multi-layer electrode structure for optimal switching performance, while the diode region uses simplified direct connection for optimal rectification performance, reducing overall assembly complexity.

Inventive Principle:

Principle #3Local quality

3Reliability

If p+-type anode layer with high impurity concentration is added to reduce contact resistance, then contact resistance decreases, but carrier discharge time increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidcarrier discharge time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent extracts and eliminates the p+-type anode layer from the diode region structure, using direct connection between aluminum electrode and p-type anode layer instead. This removal of the high impurity concentration layer reduces carrier storage and accelerates carrier discharge time while maintaining low contact resistance through the direct aluminum-to-p-type interface.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent eliminates the need for expensive and time-consuming p+-type anode layer formation process by using direct aluminum electrode connection to the p-type anode layer. This simplifies the manufacturing process and reduces carrier discharge time while achieving the desired low contact resistance performance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10957691B2Semiconductor device, semiconductor device manufacturing method, and power conversion apparatus

Publication Date: 2021.03.23 MITSUBISHI ELECTRIC CORP

AI summary

An RC-IGBT includes a first electrode disposed on a first main surface of a semiconductor substrate over a transistor region and a diode region. The semiconductor substrate includes a MOS gate structure on a first main surface side in the transistor region. The RC-IGBT includes: an interlayer dielectric covering a gate electrode of the MOS gate structure, and having a contact hole exposing a semiconductor layer; and a barrier metal disposed in the contact hole. The first electrode enters the contact hole, is in contact with the semiconductor layer of the MOS gate structure through the barrier metal, and is in direct contact with a semiconductor layer in the diode region of the semiconductor substrate.