Monolithic IGBT Diode Structure for Quasi-Resonant Converters

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Solution Overview

Problem

Conventional quasi-resonant converters require co-packaging of separate IGBT and diode dies, increasing manufacturing costs and resistance, and often necessitate complex backside processing, which can lead to snapback issues and wafer damage.

Innovation Solution

A monolithic IGBT structure integrated with a lateral diode, formed using the channel stop region, eliminating the need for co-packaging and backside processing, allowing for a larger IGBT die and smaller package size without snapback problems, and enabling separate control of injection efficiency without conventional lifetime control processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate IGBT and diode dies are co-packaged, then the device can function as a quasi-resonant converter, but manufacturing costs increase and package footprint increases

Engineering Contradiction:

Improvemanufacturing costVSAvoidpackaging complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the IGBT and diode functions into a single monolithic semiconductor structure. The IGBT device includes an integrated body diode formed by the P-type collector layer and N-type emitter layer, eliminating the need for a separate diode die. This consolidation reduces manufacturing complexity and cost while maintaining the quasi-resonant converter functionality.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If separate IGBT and diode dies are co-packaged, then the device can function as a quasi-resonant converter, but the IGBT must be made smaller increasing resistance and reducing current handling capability

Engineering Contradiction:

Improveassembly complexityVSAvoidcurrent handling capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

By integrating the diode function within the IGBT structure itself, the patent allows the IGBT to maintain its full size without needing to accommodate a separate diode die. The P-type collector layer and N-type emitter layer form the body diode intrinsically, enabling full current handling capability while simplifying assembly.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If backside processing is used to form vertical diode, then the IGBT can have integrated diode function, but additional processing steps increase production cost and risk of wafer damage

Engineering Contradiction:

Improvediode integrationVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Instead of forming the diode structure from the backside of the wafer, the patent forms the body diode intrinsically during frontside processing. The P-type collector layer and N-type emitter layer are configured to create the diode junction within the bulk structure, eliminating the need for backside masking and implantation steps.

Inventive Principle:

Principle #13The other way round (Inversion)

4Adaptability or versatility

If backside processing is used to form vertical diode, then the IGBT can have integrated diode function, but the process is more difficult to carry out and increases risk of wafer damage

Engineering Contradiction:

Improvediode integrationVSAvoidprocess difficulty

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional approach by forming the diode function during frontside processing rather than requiring backside access. The intrinsic body diode is created through the vertical P-N junction between the P-type collector and N-type emitter layers, which can be formed using standard frontside implantation and diffusion techniques.

Inventive Principle:

Principle #13The other way round (Inversion)

5Adaptability or versatility

If reverse conducting vertical diode configuration is used, then the IGBT can conduct in reverse direction, but the device suffers from snapback during device turn-on

Engineering Contradiction:

Improvereverse conductionVSAvoidsnapback stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent modifies the local structure at the collector-emitter junction to prevent snapback. By configuring the P-type collector layer and N-type emitter layer with specific doping profiles and geometric arrangements, the body diode exhibits soft recovery characteristics without snapback during IGBT turn-on, while maintaining reverse conduction capability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8502346B2Monolithic IGBT and diode structure for quasi-resonant converters

Publication Date: 2013.08.06 ALPHA & OMEGA SEMICONDUCTOR INC

AI summary

This invention discloses a semiconductor power device formed in a semiconductor substrate. The semiconductor power device further includes a channel stop region near a peripheral of the semiconductor substrate wherein the channel stop region further includes a peripheral terminal of a diode corresponding with another terminal of the diode laterally opposite from the peripheral terminal disposed on an active area of the semiconductor power device. In an embodiment of this invention, the semiconductor power device is an insulated gate bipolar transistor (IGBT).