Silicon-based and silicon carbide-based comparison

Silicon-based and silicon carbide-based comparison – Cheersonic

The first, second, third, and fourth generations of semiconductor materials have their own advantages and disadvantages, and there is no absolute substitution relationship, but they have their own comparative advantages in specific application scenarios. This should be established as a common sense perception. Performance comparison of the following materials:

Silicon is a semiconductor material, and its own conductivity is not very good. However, its resistivity can be precisely controlled by adding appropriate dopants. Before making semiconductors, silicon must be converted into wafers. This starts with the growth of silicon ingots. Single crystal silicon is a solid in which atoms periodically form in a three-dimensional spatial pattern that runs throughout the material. Polysilicon is formed by many small single crystals with different crystal orientations alone and cannot be used for semiconductor circuits. Polysilicon must be melted into a single crystal before it can be processed into wafers used in semiconductor applications. Processing a silicon wafer to produce an ingot can take anywhere from a week to a month, depending on many factors, including size, quality and end-user requirements. More than 75% of single crystal silicon wafers are grown by the Czochralski (CZ, also known as the pulling method) method.

As for silicon carbide, compared with silicon, silicon carbide has more superior electrical properties: ① High voltage resistance: The breakdown electric field strength is 10 times that of silicon. Using silicon carbide to prepare devices can greatly improve the withstand voltage capacity and operating frequency. and current density, and greatly reduce the conduction loss of the device. ②High temperature resistance: At higher temperatures, semiconductor devices will generate intrinsic excitation of carriers, resulting in device failure. The larger the band gap, the higher the extreme operating temperature of the device. The forbidden band of silicon carbide is nearly three times that of silicon, which can ensure the reliability of silicon carbide devices under high temperature conditions. The limit operating temperature of silicon devices generally cannot exceed 300 °C, while the limit operating temperature of silicon carbide devices can reach more than 600 °C.

At the same time, the thermal conductivity of silicon carbide is higher than that of silicon. The high thermal conductivity helps the heat dissipation of silicon carbide devices and maintains a lower temperature under the same output power. Therefore, silicon carbide devices have lower design requirements for heat dissipation. Contributes to miniaturization of equipment. ③ Achieve high-frequency performance: The saturated electron drift rate of silicon carbide is large, which is twice that of silicon, which determines that silicon carbide devices can achieve higher operating frequencies and higher power density. Based on these excellent characteristics, the limit performance of silicon carbide substrate is better than that of silicon substrate, which can meet the application requirements under high temperature, high pressure, high frequency, high power and other conditions, and has been used in radio frequency devices and power devices.

Next, look at the comparison of different devices.

For power devices, the size of silicon carbide-based MOSFETs with the same specifications can be greatly reduced to 1/10 of the original size, and the on-resistance can be reduced to at least 1/100 of the original. The total energy loss of silicon carbide-based MOSFETs with the same specifications can be greatly reduced by 70% compared to silicon-based IGBTs. Silicon carbide power devices have unique advantages such as high voltage, high current, high temperature, high frequency, and low loss, which will greatly improve the energy conversion efficiency of existing silicon-based power devices and have a significant and far-reaching impact on the field of high-efficiency energy conversion. The main application fields are electric vehicles/charging piles, photovoltaic new energy, rail transit, smart grid, etc. Silicon carbide devices have the advantages of low loss, high switching frequency, high applicability, and reduced system heat dissipation requirements, and will be widely used in the field of photovoltaic new energy.

For example, in string inverters in photovoltaic systems in residential and commercial facilities, silicon carbide devices bring cost and performance benefits at the system level. Leading photovoltaic inverter companies such as Sungrow have applied silicon carbide devices to their string inverters. In the electric drive system, the main inverter is responsible for controlling the motor and is a key component of the car. The main inverter of the Tesla Model 3 uses 24 silicon carbide MOSFET power modules produced by STMicroelectronics.

SiC-based GaN RF devices have the advantages of good thermal conductivity, high frequency, and high power, and are expected to open their wide applications. Gallium nitride radio frequency devices are the most ideal microwave radio frequency devices so far, so they have become the core microwave radio frequency devices of 4G/5G mobile communication systems, new generation active phased array radar and other systems. GaN RF devices are replacing LDMOS in communication macro base stations, radar and other broadband applications. With the increasing demand for data traffic, higher operating frequency and bandwidth in the information technology industry, gallium nitride devices are more and more widely used in base stations.

Gallium nitride radio frequency devices are mainly prepared based on epitaxial materials of hetero-substrates such as silicon carbide and silicon, and will also be the main choice for a period of time in the future. Compared with silicon-based gallium nitride, the main advantage of silicon carbide-based gallium nitride epitaxy lies in its low material defect and dislocation density. The epitaxial growth technology of GaN-on-SiC materials is relatively mature, and the silicon carbide substrate has good thermal conductivity, which is suitable for high-power applications. At the same time, the high resistivity of the substrate reduces the RF loss. Therefore, GaN-on-SiC RF devices have become the current mainstream of the market.

Cheersonic is the leading developer and manufacturer of ultrasonic coating systems for applying precise, thin film coatings to protect, strengthen or smooth surfaces on parts and components for the microelectronics/electronics, alternative energy, medical and industrial markets, including specialized glass applications in construction and automotive.