Shield Electrode Structure for MOSFET On-Resistance

Solution Overview

Problem

Existing MOSFET devices with recessed field plate designs face challenges such as higher gate-to-drain capacitance, excessive ringing, lower breakdown voltages, and inferior figures of merit like unclamped inductive switching, which hinder the reduction of specific on-resistance and improve switching characteristics.

Innovation Solution

The implementation of a shield electrode structure with a wide portion proximal to the channel junction and a narrow portion deeper in the drift region, separated by distinct dielectric layers, along with increased dopant concentration in the drain region near the wide portion, to reduce on-resistance and enhance switching performance while maintaining breakdown voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If recessed field plate design is used to reduce on-resistance, then specific on-resistance decreases, but gate-to-drain capacitance increases

Engineering Contradiction:

Improvespecific on-resistanceVSAvoidgate-to-drain capacitance

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The shield electrode is divided into two distinct portions: a first portion (wider) separated from the semiconductor layer by a first dielectric layer, and a second portion (narrower) separated by a second dielectric layer. This segmentation allows each portion to serve different functions in managing electric field distribution, reducing on-resistance while controlling capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the shield electrode structure have different properties: the first portion has a wider width and is separated by a first dielectric layer, while the second portion has a narrower width and is separated by a second dielectric layer. This local differentiation optimizes the balance between on-resistance reduction and capacitance control in different spatial regions.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If recessed field plate design is used to reduce on-resistance, then specific on-resistance decreases, but ringing increases

Engineering Contradiction:

Improvespecific on-resistanceVSAvoidringing

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The shield electrode is divided into two distinct portions: a first portion (wider) separated from the semiconductor layer by a first dielectric layer, and a second portion (narrower) separated by a second dielectric layer. This segmentation allows each portion to serve different functions in managing electric field distribution, reducing on-resistance while controlling capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the shield electrode structure have different properties: the first portion has a wider width and is separated by a first dielectric layer, while the second portion has a narrower width and is separated by a second dielectric layer. This local differentiation optimizes the balance between on-resistance reduction and capacitance control in different spatial regions.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If recessed field plate design is used to reduce on-resistance, then specific on-resistance decreases, but breakdown voltage decreases

Engineering Contradiction:

Improvespecific on-resistanceVSAvoidbreakdown voltage

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The shield electrode is divided into two distinct portions: a first portion (wider) separated from the semiconductor layer by a first dielectric layer, and a second portion (narrower) separated by a second dielectric layer. This segmentation allows each portion to serve different functions in managing electric field distribution, reducing on-resistance while controlling capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the shield electrode structure have different properties: the first portion has a wider width and is separated by a first dielectric layer, while the second portion has a narrower width and is separated by a second dielectric layer. This local differentiation optimizes the balance between on-resistance reduction and capacitance control in different spatial regions.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS8907394B2Insulated gate semiconductor device having shield electrode structure

Publication Date: 2014.12.09 SEMICON COMPONENTS IND LLC

AI summary

In one embodiment, a semiconductor device includes a multi-portion shield electrode structure formed in a drift region. The shield electrode includes a wide portion formed in proximity to a channel side of the drift region, and a narrow portion formed deeper in the drift region. The narrow portion is separated from the drift region by a thicker dielectric region, and the wide portion is separated from the drift region by a thinner dielectric region. That portion of the drift region in proximity to the wide portion can have a higher dopant concentration than other portions of the drift region.