May 26, 2024

How Superjunction MOSFETs Improve Power Efficiency

Electrical Engineering, Energy efficiency, Low Power Consumption, MOSFET Technology, Power efficiency, Power Electronics, Semiconductor technology, Superjunction MOSFETs, Superjunction Technology

In the world of power semiconductor devices, superjunction MOSFETs lead the way. They are the top pick for designers who care about energy use and want more efficient switching power systems. Thanks to superjunction technologies, reduced die sizes are possible. This lets designers save space and improve current density. Yet, these technologies also bring new challenges. For instance, there’s a growing need to cut back on noise performance. Minimizing electromagnetic noise is crucial in high-quality power supplies for many items, including LCD TVs and LED lighting.

It also impacts medical power supplies, notebook power adapters, and power supplies for tablets.

What is a Superjunction MOSFET?

In a conventional MOSFET, the drift region causes most of the on-state resistance for a 600V device. The superjunction method fixes this issue. It uses deep p-doping in the drift region. This balances against the highly doped n-regions. This happens during electron flow. In the off-state, it creates a space charge depletion region. This ensures even electric fields and a High Breakdown Voltage.

Conventional MOSFET Structure and Limitations

Most of the on-state resistance in a conventional MOSFET comes from its drift region. This is a big problem. It hampers the devices’ performance and efficiency.

Superjunction Architecture and Charge Balancing

The superjunction overcomes the high on-state resistance problem. It involves using deep p-doping in the drift region. This balances against the highly doped n-regions. It maintains a uniform electric field in the off-state. This allows for a High Breakdown Voltage.

Advantages of Superjunction Technology

The superjunction can be made much smaller for a given RDS(ON). This makes it switch better. Unlike traditional MOSFETs, it does this by reducing the RDS(ON). This is done by decreasing the pitch and upping the doping. It breaks the 1979 silicon limit based on 1-D Poisson theory.

Working Principle of Superjunction MOSFETs

In a superjunction MOSFET, the N-region is heavily doped. This step takes its resistivity beyond the silicon limit. Two P-type material pillars surround this N-region, allowing a very high breakdown voltage. High breakdown voltage and very low RDS(ON)*A are the key features of the superjunction architecture. This design is perfect for power MOSFETs. It saves space without sacrificing power.

Charge balancing is vital for superjunction MOSFETs. The N-regions, rich in electrons, are well matched by the P-type pillars. This balance creates a steady electric field. It helps achieve a high breakdown voltage.

The superjunction architecture is special. It reduces the device’s on-state resistance (RDS(ON)) significantly. This drop in resistance does not affect the breakdown voltage. Thus, superjunction MOSFETs are a top pick for power electronics needing high efficiency and power density.

Low On-Resistance and High Breakdown Voltage

Superjunction MOSFET tech is all about beating the limits of silicon. It does this by shrinking the size of p-type pillars and making the doping stronger. With this, the on-resistance (RDS(ON)) drops, meaning we can make the devices smaller. This move is a big win, cutting down output capacitance (COSS) and making devices switch better.

Overcoming Silicon Limits with Superjunction Design

The superjunction layout lets us go past old silicon limits. It uses clever balance between the p-type and n-type regions. This trick sharply drops RDS(ON) but keeps the high breakdown voltage needed for high-voltage uses.

Reduced Die Size and Increased Current Density

Making superjunction MOSFETs smaller for the same RDS(ON) boosts their switching and lets them handle more electricity. The smaller size is great for using less space and managing heat well. This is key for making power systems work better.

Low On-Resistance and High Breakdown Voltage

Fabrication Techniques for Superjunction MOSFETs

Superjunction MOSFETs are made using two main methods: a multi-epitaxial and a deep trench approach. Each way has its own benefits and problems for making the device work well and be easy to produce.

Multi-Epitaxial Approach

The multi-epitaxial way plants a p-type layer between n-type layers. This helps with setting the right charge balance. Yet, it can be hard to control the process perfectly, leading to issues in creating the best Superjunction MOSFETs.

Deep Trench Etching and Re-Growth

The deep trench method includes carving out spaces for p-type columns and then filling them. It allows for better side-to-side control and makes the device perform better. But, it’s tough to do this without pitfalls in production.

Both methods have their good sides and downfalls. Experts are working to make these ways better so Superjunction MOSFETs can do even more and be easier to make.

Performance Advantages of Superjunction MOSFETs

Superjunction MOSFETs have clear benefits over standard silicon types. They have lower on-resistance and smaller die sizes. This means they cause fewer Reduced Conduction Losses and Reduced Switching Losses.

Superjunction MOSFETs’ output capacitance (COSS) changes a lot, helping with almost-no-power turn-offs. This makes them work well at High Frequency Operation.

Reduced Conduction and Switching Losses

The superjunction process includes adding platinum that shortens the carriers’ lives. This makes the body diode recover faster, a key advantage over wide bandgap devices. Their unique pillar structure also makes them perform reliably at up to 150°C.

Improved Switching Behavior and High Frequency Operation

Superjunction MOSFETs’ COSS has a unique behavior that aids in nearly power-less turn-offs, perfect for High Frequency Operation. Platinum in their process decreases recovery times, another advantage over wide bandgap devices.

Temperature Stability and Reliability

The structures in superjunction MOSFETs are more consistent. This contributes to their stable performance and reliability even at high temperatures up to 150°C.

Applications of Superjunction MOSFETs

Superjunction MOSFETs are widely used in fields that need both power and efficiency. They shine in areas like solar inverters, energy systems that are renewable, power supplies, motor controls, and lighting. Their abilities make these areas work better.

Solar Inverters and Renewable Energy Systems

In solar power systems, these MOSFETs are key. They help get more energy out of solar panels by losing less in the process. Their design, with low resistance and high voltage, boosts efficiency. This means more power from the sun ends up being useful energy.

Power Supplies and Motor Control

These MOSFETs are crucial in powering machines and controlling motors. They cut down on how much energy is lost when power flows through them. This makes machines more efficient. Their smaller size and better ability to switch also help make power systems smaller and work better.

Lighting and Ballast Applications

For lights and ballasts, these MOSFETs bring big wins in saving energy and managing heat. Their low resistance and quick switching lower how much energy is wasted. This leads to brighter lights and more reliable systems, without using more power.

Superjunction MOSFET Applications

How Superjunction MOSFETs Improve Power Efficiency

Superjunction MOSFETs boost power efficiency in several ways. They have a low on-resistance and smaller die size. This leads to less energy lost in conduction and switching, which cuts down heat loss. Making designs smaller, thanks to superjunction technology, also means more power packed in one place.

Their better switching, staying stable at higher temperatures, and being more reliable help too. All this adds up to systems needing less power and lasting longer. That’s why they’re ideal for devices that need to use energy wisely.

Reduced Energy Losses and Heat Dissipation

Because superjunction devices have a low on-resistance and are smaller, they lose less energy and create less heat. This means they handle power better and keep the system cool. Overall, your devices will perform more efficiently.

Smaller Form Factors and Higher Power Density

Superjunction technology makes devices smaller, offering higher power density. This lets designers fit more power in less space. As a result, your electronic setups become more efficient and tidy.

Improved System Efficiency and Reliability

The better switching, staying stable at higher temperatures, and reliability of superjunction MOSFETs also mean they last longer. They improve how well your system works over time. This is great for setups that need to work hard without wasting energy.

Comparison with Wide Bandgap Devices

Devices like silicon carbide (SiC) MOSFETs and gallium nitride (GaN) transistors have pros over silicon ones. They boast lower losses when conducting and faster switching. Still, superjunction silicon devices hold their own in low and medium frequency uses.

Silicon Carbide (SiC) MOSFETs

SiC MOSFETs are available in both planar and trench shapes. They support voltages from 1.2 kV to 6.5 kV. With a top voltage of 1,200 V and high current abilities, they fit many power electronics tasks.

Gallium Nitride (GaN) Transistors

Gallium nitride (GaN) transistors excel in moving electrons and managing heat better. GaN FETs operate at 600 V and drive high-density converters of 10 kW or more. While superjunction silicon MOSFETs have advantages, GaN devices show constant progress in performance through better making methods.

Interestingly, GaN needs over 50% less energy to switch than SiC. This means it loses less power in the PFC stage. The newest GaN devices reach amazing switch rates and cut losses by 82% against SiC. GaN can outdo both SiC and superjunction in a 1-kW PFC task.

Using GaN in a multilevel setup offers better switching features than SiC or IGBT in grid converters. It also leads to better heat spreading and lets the system pack more power in a smaller space. TI GaN devices in multilevel converters hit 99.2% efficiency, topping IGBTs and SiC devices. They also allow for better power density.

Even with its strengths, the price difference between superjunction silicon and wide bandgap devices is getting smaller. Wide band devices gain more use, further reducing this gap. This keeps superjunction silicon MOSFETs as a strong choice for medium and low frequency power conversion applications.

Future Trends and Developments

The need for efficient power electronics is growing. This growth will lead to more steps forward in superjunction MOSFET technology. These advancements aim to make devices work better and last longer, even at high temperatures.

Superjunction MOSFETs are also being made smaller and more reliable. This is thanks to work on how they connect with other parts, like gate drivers and control systems. These changes make power systems both more powerful and smaller.

The superjunction silicon devices are getting cheaper compared to other types. This means they will be used more often in different electronic devices. The superjunction MOSFET market is set to grow steadily from 2024 to 2032, driven by a need for better energy use.

Big companies like ON Semiconductor, STMicroelectronics, and Infineon are pushing these developments further. They are creating better products that use less energy and take up less space. This technology is not only for future electronics. It’s also for use in cars, factories, phones, green energy, and the internet.

How Superjunction MOSFETs Improve Power Efficiency

What is a Superjunction MOSFET?

Conventional MOSFET Structure and Limitations