What is SiC MOSFET? Introducing the challenges of silicon and the benefits and features of using SiC!

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Basic Analog Discrete Power Devices On Semi

Introduction

Si (silicon) semiconductors have been widely used in power semiconductors, but in recent years, their performance has been reaching their limits. It is becoming difficult to meet such demands.

Instead, SiC power semiconductors using the wide bandgap material SiC (silicon carbide) are attracting attention.
SiC power semiconductors that support high withstand voltage, high heat resistance, and high-speed switching, especially SiC MOSFETs, are divided into the following three topics and explained in detail.

・ Why is SiC attracting attention? Difference between Si (silicon) and SiC

・Issues of Si (silicon) power semiconductors

・Features of ONSEMI's SiC MOSFET "M1-M3 Family"

Why is SiC attracting attention? Difference between Si (silicon) and SiC

Today, the amount of power required in various situations and applications is increasing dramatically.

On the other hand, the Si (silicon) power semiconductors that have been used so far are approaching the theoretical limit called the silicon limit, and significant improvement cannot be expected.

Figure 1: Theoretical voltage and resistance limits (Note)

Under these circumstances, demand is growing for wide bandgap semiconductors that use new materials such as SiC (silicon carbide).

A wide bandgap semiconductor is a semiconductor with a large bandgap energy, that is, the energy required to move an electron from the valence band to the conduction band.
The bandgap energy of SiC is about three times that of Si, and it behaves more like an insulator than a conductor. Therefore, it is possible to make products with higher withstand voltage than Si.

For example, the introduction of SiC power semiconductors is progressing for the following products (applications).

・Traction inverter
・EV fast charging charger
・Power supplies for industrial equipment
・Special power supply for semiconductor manufacturing equipment
・Solar inverter

Issues with Si (silicon) power semiconductors

Silicon power semiconductors have been used in the development of the above products (applications), and the following issues have arisen.

Issue (1) Support for high withstand voltage and high-speed switching

Super junction MOSFET (SJ MOSFET) and IGBT are used depending on the product characteristics.
However, "super junction MOSFETs are not suitable for large currents compared to IGBTs" and "IGBTs are difficult to switch at high speed", making it difficult to support high withstand voltages, large currents, and high-speed switching.

Issue (2) Miniaturization of the final product

As the amount of power required increases, the size of the final product is becoming noticeably larger.
While the need for miniaturization is increasing due to installation and transportation convenience, it is difficult to respond to miniaturization because the switching speed of silicon power semiconductors is insufficient and the number of parts cannot be reduced.

Issue (3) Heat generation from devices

Heat is a problem when driving a motor.
Since silicon power semiconductors have a large power loss and generate a large amount of heat, complex heat dissipation measures are required.

We would like to recommend ONSEMI's extensive lineup of SiC power semiconductors to those who have such issues.
SiC power semiconductors with low on-resistance and high reliability contribute to high efficiency and miniaturization of various products.

Features of ONSEMI's SiC MOSFET "M1-M3 Family"

ONSEMI offers SiC power semiconductors with various specifications such as Schottky barrier diodes, MOSFETs and modules.
Here, we will focus on SiC MOSFETs. Its features are as follows.

Features (1) Supports main withstand voltages and 900V withstand voltage

In addition to 650V, which is in demand to replace superjunction MOSFETs, and 1200V and 1700V, which are in demand to replace IGBTs, ONCEMI has released 900V devices, which are not supported by many vendors. It covers standardly used packages such as "TO-247 3pin", "TO-247 4pin", and "D2PAK 7pin".

Features (2) Full lineup of low on-resistance products

We have a lineup of multiple low on-resistance devices that our competitors do not have.

For example, 14mΩ of 1200V D2PAK 7pin and 650V TO-247 3pin / D2PAK 7pin have the lowest ON resistance compared to other companies with the same voltage and same package.
Furthermore, the 1200V withstand voltage TO-247 4pin with 14mΩ and the 650V withstand voltage TO-247 4pin with 12mΩ are also the lineup with the lowest on-resistance for MOSFET structures. (Compare with ON resistance value at Vgs=18V)

Features (3) Securing about twice the creepage distance

By installing a slit in the TO-247 4-pin package, the creepage distance is doubled compared to competitors' products in the same package.
The longer the creepage distance, the higher the resistance to high voltage. This package is extremely advantageous in cases where a certain or more creepage distance is required.

Features (4) Highly reliable gate terminal

ONSEMI devices also have excellent gate terminal reliability.
In stress tests with high gate loads at high temperatures, ONSEMI devices maintain a nearly constant threshold voltage.
On the other hand, other companies' devices change the threshold voltage over time.

特長(5) 導通損失・スイッチング損失を大幅削減

The latest generation of the M3 family has significantly reduced switching losses compared to its predecessor.
This further improves efficiency and reduces heat generation.
Superior performance compared to ONSEMI's M1 family and comparable devices from competitors.

The figure below is a graph comparing the switching loss Eon at turn-on. (Left: Room temperature, Right: 150 ℃)