Deconstructing the origin of MOSFET

This article was contributed by Ashita Mirchandani, Head of Device Design and Technology Development, and Bastian Lang, Product Marketing Manager, Infineon Technologies AG

Over the past 50 years, our world has undergone tremendous changes. Various new economic, social and technological trends have emerged and are profoundly affecting people's daily lives in different ways.

However, no matter how the world changes and to what extent,

One thing remains constant:

Technology plays a vital role in this .

However, looking at the value chain behind these solutions,

We can see that it all comes down to the smallest detail:

Microchip

There is no doubt that the correct selection of the appropriate power switching device determines the performance (including reliability) of the entire system.

Always at the forefront of critical power semiconductor innovation

With more than 40 years of experience in power MOSFET innovation , Infineon has been leading the way in helping design engineers solve the challenges they encounter in their daily work and achieve their design goals. Although these goals may have changed in recent years, the innovative spirit behind Infineon products has always been throughout the entire process from device design, technology, packaging, product development to manufacturing.

Looking back at the development history of the MOSFET industry, the continuous advancement of MOSFET technology has greatly enriched its product applications and market prospects , and has become an indispensable part of our lives. In 1979, the first hexagonal topology MOSFET was launched . In 1995, a new generation of MOSFET technology was launched : this technology is based on an advanced four-mask process, using innovative self-alignment features to improve manufacturing accuracy and yield; this process significantly shortens the manufacturing cycle of MOSFET (compared to the requirements of the six-step process), and the junction depth is reduced by 40% compared to the traditional process, thereby greatly reducing the transistor junction resistance and improving robustness.

Soon after these technologies were developed, the world's first FETKY product was born : it integrated MOSFET and Schottky diode into one package, greatly reducing the size and power loss of DC-DC converter products.

Later, in 1999, a new stripe planar technology was introduced : it uses advanced manufacturing expertise to achieve a fully self-aligned manufacturing process; its biggest feature is its high-density planar structure, which can provide extremely low on-resistance, excellent high-frequency operating characteristics, the industry's best product robustness and excellent manufacturing cycle. In the same year, the industry's highest cell density and lowest on-resistance R _DS(on) Trench MOSFET product series was also launched : this technology focuses on providing the latest products for mobile phones, laptops and other various portable electronic devices, and also paves the way for better performance products to be launched.

In 2000, the first ultra-low switching loss OptiMOS™ MOSFET product series was released , which can help designers improve efficiency and increase power density. After years of development, the OptiMOS™ series has now evolved to the sixth generation. OptiMOS™ products provide extremely low R _DS(on) and excellent high-frequency switching performance. The OptiMOS™ series is optimized for various applications and circuits , such as synchronous rectification and OR-ing circuits in switch mode power supplies (SMPS) in servers, desktop computers, wireless chargers, and fast chargers. In addition, in 2012, the low R _DS(on) and high current capability StrongIRFET™ series MOSFET products were launched , which are ideal for low-frequency applications that require both parameter performance and product robustness.

figure 1

Infineon's 12-300 V power MOSFET products

Technology development and product range

Packaging innovation is also at the core of Infineon’s MOSFET product development. In 1993, we introduced the industry’s first surface-mount power MOSFET package: SOT-223 . In 2002, we introduced a patented surface-mount package: DirectFET ™ power package : it uses a new connection method and has revolutionary performance improvements in both conduction and thermal efficiency. In 2013, the now widely used TO-Leadless package ^{was introduced: compared with the traditional D2PAK} package , it can achieve higher current capabilities in a smaller package size. Recently, Infineon introduced the OptiMOS™ power MOSFET product family in the PQFN 3.3 x 3.3 Source-Down package , whose internal die is upside down (source at the bottom), which greatly improves thermal performance and reduces R _DS(on).

figure 2

StrongIRFET™ and OptiMOS™ product families

High performance in a space-saving package

Let’s take a closer look

Benefits of packaging innovation for specific applications

Chip-level innovation to improve system performance

The application example chosen here is artificial intelligence. Power management, and more specifically the power density of the power converters that power the processors and ASICs in the system, is one of the biggest challenges designers face in implementing artificial intelligence and meeting the demands of cloud computing and cloud storage.

With the introduction of 48V bus voltage, more power conversion links are introduced into the power chain. This conversion must be performed close to the effective load to avoid transmission losses and better benefit from the higher bus voltage of 48V. With Infineon's hybrid switched capacitor (HSC) resonant DC-DC converter solution and Infineon's latest Source-Down OptiMOS™ power MOSFET devices , innovation in power conversion can be achieved at the system level. This new topology shows great potential to improve power density and efficiency levels compared to the current mainstream conversion scheme. Combined with Infineon's new Source-Down MOSFET product family , this solution can achieve overall optimization starting from the bottom, device innovation, while taking into account system performance.

To overcome the power density challenge,

This requires innovation at the device level.

and improvements in resonant topologies.

With the introduction of Infineon's Source-Down packaging technology , the IQE006NE2LM5 product further enhances the electrical and thermal performance of power devices, thereby achieving the high power density required for modern data center applications. The main advantages of this innovative packaging include:

To compare performance advantages

We tested both

8:1 Hybrid Switched Capacitor (HSC) Converter

One is based on the traditional Drain-Down device (BSZ011NE2LS5I) , and the other is based on the new Source-Down device (IQE006NE2LM5) .

Figure 2 shows a comparison of the thermal performance of the devices. When using the conventional package, a hot spot can be observed ( Figure 3a ); however, this hot spot can be eliminated when using the new Source-Down package ( Figure 3b ). The surface temperature of the Source-Down MOSFET is significantly improved: 9°C lower than the Drain-Down device. Figure 4 shows the efficiency comparison (including auxiliary power losses). The system with the new Source-Down device is more efficient and the power density is significantly improved.

image 3

(Left: Figure 3a, Right: Figure 3b)

Thermal performance of HSC converter at 48 V input, 450 W:

a) Using BSZ011NE2LS5I, b) Using IQE006NE2LM5

Figure 4

BSZ011NE2LS5I and IQE006NE2LM5

At Tamb ₌ 24°C and v = 3.3 m/s,

Efficiency of HSC converter at 48 V to 6 V

(Including auxiliary power loss)

Current social trends that affect people's daily lives,

For Design Engineers and Semiconductor Manufacturers

Brought severe challenges.

Over the past 40 years,

Infineon 's power MOSFET innovations have proven:

Device-level optimization can significantly improve system performance advantages.

And it can help create an easier, safer and greener future.

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