With the arrival of a new computing era driven by the Internet of Things (IoT), big data and artificial intelligence (AI), the demand for energy-saving chips is steadily increasing. In this case, we usually consider Moore's Law to reduce the size of the transistor.

However, the advancement of power semiconductors does not depend on the reduction of transistor size. Silicon power switches, such as MOSFET (metal-oxide semiconductor field effect transistor) and IGBT (insulated gate bipolar transistor), are used to handle voltages from 12V to +3.3kV and currents of hundreds of amperes. These switches consume a lot of energy! However, their limited capabilities have promoted the development of new materials such as silicon carbide (SiC), which are expected to provide excellent performance.

Silicon carbide is a compound semiconductor material that combines silicon and carbon to create a super cousin of silicon. Compared with silicon, silicon carbide requires more than three times the energy to make electrons move freely. This wider band gap gives the material interesting properties, such as faster switching and higher power density. The following will focus on two use cases to see the significant benefits that SiC devices can bring.

SiC used in cars

Data from research company Yole development shows that there are more than 1 billion cars in the world. As of 2017, 1.9 million vehicles (about 0.2%) are electric vehicles. By 2040, this proportion is expected to increase to 50%. Therefore, improving power efficiency is essential.

Electric vehicles usually have a main engine to drive the wheels, and six power transistors and diodes are used to drive the motor. Each transistor needs to be able to block 700V and convert hundreds of amps. Most power switches use pulse width modulation (PWM) technology, which means they turn on/off thousands of times per second. When the transistor is turned on/off, there is a transition delay between states (Figure 1). Just like opening/closing a faucet, it takes a certain amount of time to completely open/close the valve. During this time, some water may be wasted. The same principle applies to transistors. In power applications, an important goal is to increase the switching speed as much as possible to reduce switching losses and achieve higher efficiency.

Better switching performance, low on-resistance, and high breakdown voltage make SiC devices an ideal replacement for traditional silicon power devices (MOSFETs), DC-DC converters, uninterruptible power supply systems, and motor applications (Figure 2).

Using SiC MOSFETs can drive the motors of electric vehicles with less power, and ultimately increase the mileage of electric vehicles. Because higher switching frequency brings higher power density and smaller and lighter motors, the reduction in heat waste allows electric vehicles to use smaller and lighter radiators, further optimizing vehicle weight and mileage.

SiC for solar

Another application of SiC is solar inverters, which are only half the size of IGBT-based solutions. The faster switching speed of SiC means that manufacturers can reduce the size of passive components in the system. Large capacitors and transformers can be replaced with smaller alternatives, while reducing the size of the heat sink. As system efficiency increases, energy capture is maximized.

Use SiC

Despite the exciting potential of SiC equipment, there are still manufacturing problems. A major problem is substrate defects. In order to achieve the high yields required for commercial success, SiC devices must reduce these defects. Applied Materials is working with ecosystem participants, including SiC wafer manufacturers and IDM (Integrated Device Manufacturer) companies, to specifically address manufacturability issues. We will discuss developments in this area later.

Many industry forecasters believe that SiC will eventually replace silicon in higher voltage and high power applications. Like all superheroes, when the industry accepts SiC, it will be able to cope with greater power consumption and efficiency challenges, thereby making the world a better place.