GaN and SiC - The third-generation semiconductor material, has long been widely used in blue and green LEDs and lasers. GaN and SiC have become a must-have technology for many manufacturers.
What are the Third Generation Semiconductor and Wide-bandgap Semiconductors?
In the field of semiconductor materials, the first-generation semiconductor is Si, the second-generation semiconductor is GaAs, and the third-generation semiconductor (Wide-bandgap semiconductors, WBG) is SiC and GaN. The Energy gap in a wide-bandgap semiconductors represents an energy gap, which means the minimum energy required to make a semiconductor from insulation to conduction. 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 gaps of the third generation wide-bandgap semiconductors, SiC and GaN reach 3.2 eV and 3.4 eV respectively, so 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, with more stable characteristics and better energy conversion.
With the wide-bandgap semiconductors (WBG) power components of the third-generation semiconductor materials being widely used in 5G base stations, low-orbit satellites, electric vehicles, mobile phone fast charging, and other markets, Taiwan's semiconductor production chain has been actively deploying in the GaN and SiC fields in recent years.
The Development of Taiwan's Semiconductor Industry:
Taiwan's semiconductor industry takes the existing silicon-based semiconductor ecosystem and research energy as a good foundation. Through the power of the association, it integrates major domestic and foreign manufacturers and the government, academia, and research community to jointly build a transnational and cross-domain collaboration and integration platform. By building a complete supply of compound semiconductors chain to help Taiwan expand into a larger global semiconductor ecosystem. Therefore, it is necessary and immediate to maintain Taiwan's dominance in compound semiconductors. In the past, Taiwan used silicon semiconductors to support the entire ICT industry chain and played a key role in the global technology industry. If it can gradually develop to the height of silicon semiconductors in the field of wide-bandgap semiconductors, it will not only continue Taiwan's advantages in the semiconductor industry but also increase its competitiveness. Continue to make contributions to the global technology industry and economic development.
Compound semiconductors have been listed as key national development projects all over the world, and Taiwan's niche advantages include not only the "compound semiconductor program" actively launched by the government, but also the integration of resources from industry, government, and academia to promote talent training programs. For example, universities and colleges are encouraged to increase compound semiconductor scholarships to recruit outstanding talents from all over the world, establish an employment-oriented technical and vocational system and cultivate low-level technical manpower, etc., to stabilize Taiwan's leading and key position in the global compound semiconductor industry chain. Today's compound semiconductor technology is becoming more and more complex, and how to make up for the insufficiency of the existing supply chain through upstream and downstream cooperation is an important issue. Looking at the supply chain of compound semiconductors in Taiwan, Taiwan has many wafer factories, and silicon carbide substrates, gallium nitride epitaxy, and corresponding production equipment are key projects that can be developed.
Power Transistor Technology Background:
- Low on-resistance to reduce conduction losses in the on-state for efficient power conversion
- High-speed switching performance to reduce switching loss
- Noise energy during abnormal operation of power conversion in the role of the circuit as an absorption source, when an overvoltage is applied in the off state, the transistor causes a non-destructive breakdown and absorbs the noise energy as thermal energy to ensure power conversion reliability of the device.
The Differences Between Semiconductor Materials GaN and SiC:
- GaN has a faster frequency: Suitable for consumer device charging, light gasoline power, hybrid power, and 5G radio frequency communication applications.
- SiC has a higher withstand voltage capability: Suitable for applications that require higher voltages such as electric vehicles, supercharging stations, vehicles, and energy sources.
The Applications of Semiconductor Materials GaN and SiC:
In the era of the Internet of Things, green energy, and 5G, the energy efficiency of electronic equipment is more important, and compound semiconductors such as SiC and GaN are the key to improving efficiency. Since the withstand voltage and output power of SiC and GaN are different, they can perform in different fields. 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 are more prone to failure when it is more severe, 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 a breakthrough application in the era. 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.
SiC and GaN have some overlapping voltage levels and frequencies. SiC is mainly aimed at 600V~3.3kV for high voltage applications in the electric vehicle market; while GaN is expected to open new prospects in 100V~600V power electronics. In addition, GaN has a switching frequency of more than 1 MHz, so in addition to its application in the field of power charging, GaN has a greater market opportunity in 5G wireless communication. In practical applications, SiC has better technology maturity, so the market is growing rapidly, and the application in the xEV market is also increasingly widespread.
SiC is composed of Si and C, which has a strong bonding force and is thermally, chemically, and mechanically stable. Due to the characteristics of low consumption and high power, SiC is suitable for high-voltage and high-current application scenarios, such as electric vehicles and electric vehicle charging. Infrastructure, solar and offshore wind power, and other green power generation equipment.
The characteristics of small size, low heat generation, and high wattage make GaN very suitable for fast charging of consumer electronic products, and the characteristics of high withstand voltage allow GaN to exert the greatest competitive advantage in the fields of automobile, industry, and telecommunications. In addition to consumer electronics, GaN also has wide adoption opportunities in the automotive field, such as 48V hybrid, DC-DC voltage conversion, in-vehicle wireless charging, in-vehicle data center servers, and even lidar's high-power laser drive, etc., are suitable for the use of GaN fields. In the long run, consumer electronics, automotive, and industry are the three main application areas for GaN power semiconductors.
Advantages of GaN:
- Lower on-resistance: reduces losses and improves the energy conversion efficiency.
- Faster electron migration rate: increase the frequency of the AC circuit and reduce the external components and volume required.
- Higher voltage withstands capability: higher wattage charging, increasing charging speed.
- GaN enables higher power, higher power efficiency, smaller device size, and lower system cost.
Technical Requirements for Testing, Etching, and Packaging of Semiconductor Materials GaN and SiC:
Over the past few decades, the packaging of power chips has been pursuing miniaturization, better thermal performance, and better electrical characteristics, and the packaging technology used has become increasingly complex. In the early years, almost all power chips were packaged by wire bonding, but in recent years, power chips using flip-chip packaging have become more and more common. To further achieve a higher degree of integration in a single package, many chip manufacturers have developed packaging technology that integrates active and passive components on the same substrate and launched products that look like chips but are modules.
In the inspection part, as far as SiC is concerned, the most critical is the defect inspection before wafer casting, because the probability of defects in SiC wafers is high, so wafer defect inspection before production is very critical. The opposite is true for GaN devices, where the most difficult part is that the etch process cannot damage the GaN structure, which would negatively affect device reliability. Therefore, for GaN components, the inspection focus is on the inspection after the etching process.
As for the etching part, the most challenging part of SiC etching is how to speed up the etching and end-point detection of processing. Rapid etching of this material is difficult due to the relatively high hardness of SiC. In addition, because the transistors of SiC components will adopt trench structures in the future, which means that the end point of processing will be in the blind area, and it is a relatively challenging task to control the etching depth just right through the endpoint detection.
In terms of GaN etching, the GaN layer is quite sensitive to the damage caused by the etching process, so during the etching process, the speed must be slowed down and carried out carefully. At present, SPTS has been able to control the reaction furnace to the limit that the plasma is about to disappear, thereby reducing the etching speed to the slowest, to avoid damage to the device structure as much as possible.