What Exactly is the Third Generation Semiconductor? GaN, SiC are The Key Technology?

As the world enters the era of IoT, 5G, green energy, and electric vehicles, Wide Band Gap (WBG) semiconductors that can fully demonstrate high-voltage, high-temperature, and high-frequency capabilities and meet the requirements of current mainstream applications for high energy conversion efficiency Beginning to become the darling of the market, semiconductor materials opened the prelude to the new era of the third-generation semiconductor.

What is the Third Generation Semiconductor and Wide Energy Gap?

When it comes to the third-generation semiconductors, let’s first briefly introduce the first and second-generation semiconductors. In the field of semiconductor materials, the first generation semiconductor is "silicon" (Si), the second generation semiconductor is "gallium arsenide" (GaAs), and the third generation semiconductor (also known as "wide energy gap semiconductor", WBG) is "Silicon carbide" (SiC) and "gallium nitride" (GaN).

The "energy gap" in wide-gap semiconductors, in the most vernacular way, represents "one energy gap", which means "the minimum energy required to make a semiconductor go from insulating to conducting."

The silicon and gallium arsenide of the first and second generation semiconductors are low energy gap materials, with values ​​of 1.12 eV and 1.43 eV respectively. The energy gap of the third generation (wide energy gap) semiconductors, SiC and GaN reach 3.2 eV and 3.4 eV, respectively. Therefore, when encountering high temperature, high voltage and high current, compared with the first and second generation, the third generation semiconductor will not easily change from insulating to conductive, the characteristics are more stable, and the energy conversion is better.

The Third-Generation Semiconductor Myth

With the advent of the era of 5G and electric vehicles, the demand for high-frequency, high-speed computing, and high-speed charging of technology products has increased. The temperature, frequency, and power of silicon and gallium arsenide have reached the limit, and it is difficult to increase the power and speed; once the operating temperature exceeds 100. The first two generations of products are more prone to failure, so they cannot be used in more severe environments. In addition, the world has begun to pay attention to the issue of carbon emissions, so the third-generation semiconductors with high energy efficiency and low energy consumption have become the new darling of the times.

The third-generation semiconductors can still maintain excellent performance and stability at high frequencies, and at the same time have the characteristics of fast switching speed, small size, and rapid heat dissipation. The volume of the module and cooling system.

Many people think that third-generation semiconductors, like advanced manufacturing processes, are accumulated from the technologies of first- and second-generation semiconductors, but this is not the case. From the picture, these three generations of semiconductors are actually in a parallel state, and they develop their own technologies. Since China, the United States, and the European Union are actively developing third-generation semiconductors, Taiwan, one of the keys to the semiconductor industry chain, is bound to keep up with this trend.

SiC and GaN Have Their Own Advantages and Different Development Fields

After understanding the differences of the first three generations of semiconductors, we then focus on the materials of the third generation semiconductors - SiC and GaN. The application fields of these two materials are slightly different. At present, GaN components are often used in fields with voltages below 900V, such as chargers, bases Taiwan, 5G communication-related and other high-frequency products; SiC is a voltage greater than 1,200 V, such as electric vehicle-related applications.

SiC is composed of silicon (Si) and carbon (C), which has strong bonding force and is thermally, chemically, and mechanically stable. Due to the characteristics of low loss and high power, SiC is suitable for high-voltage and high-current application scenarios, such as Electric vehicles, electric vehicle charging infrastructure, solar and offshore wind power and other green energy power generation equipment.

In addition, SiC itself is a "homogenous epitaxy" technology, so it has good quality and good component reliability. This is also the main reason why electric vehicles choose to use it. In addition, it is a vertical component, so the power density is high.

Today, the battery power system of electric vehicles is mainly 200V-450V, and higher-end models will develop towards 800V, which will be the main market for SiC. However, SiC wafers are difficult to manufacture, and the source crystals for crystal growth are highly demanding and difficult to obtain. In addition, the crystal growth technology is difficult, so mass production is still not possible at present, which will be described in more detail later.

GaN is a lateral element and is grown on different substrates, such as SiC or Si substrates. It is a "hetero-epitaxy" technology. The quality of the GaN film produced is poor. Although it can be used in consumer areas such as fast charging, it is used in electric vehicles. Or there are some doubts in the industry, and it is also the direction that manufacturers are eager to break through.

The application fields of GaN include high-voltage power components (Power) and high-frequency components (RF). Power is often used as a power converter and rectifier, while the commonly used Bluetooth, Wi-Fi, and GPS positioning are among the applications of RF components. one.

In terms of substrate technology, the production cost of GaN substrates is relatively high, so GaN components are all based on silicon. GaN-on-SiC) two wafers are fabricated.

Commonly heard GaN process technology applications, such as the above-mentioned GaN RF RF components and Power GaN, all come from GaN-on-Si substrate technology; as for GaN-on-SiC substrate technology, due to the difficulty of manufacturing silicon carbide substrates (SiC), The technology is mainly in the hands of a few international manufacturers, such as Cree, II-VI and ROHM.

Although the third-generation semiconductors have better performance in terms of performance, their technical threshold is higher, and not all electronic components and technical applications require such high performance, so the third-generation semiconductors will not completely replace the previous ones. After the second generations have been replaced by the old, in principle, the third generations will each play an important role in different fields. Basically, the first generation will focus on logic ICs, memory ICs, micro-component ICs and analog ICs used in computers and consumer electronics, the second generation will focus on RF chips in the field of mobile communications, and the third generation will focus on The biggest driving force comes from the fields of 5G, IoT, green energy, electric vehicles, satellite communications and military, and high-frequency radio frequency components and high-power power semiconductor components are the main applications. Among them, 5G and electric vehicles are regarded as the biggest drivers and driving forces to accelerate the development of third-generation semiconductors.