SiC substrate’s superior thermal conductivity and resistance to high temperature and current make it an excellent material choice for power devices, with costs comprising 40%-50% of final die cost accounting for savings to be realized. However, these savings must come at the expense of material costs alone; further savings must be achieved elsewhere.
Soitec made an impressive move at CS International 2023 by unveiling their groundbreaking SmartSiC process, consisting of mono-SiC donor wafers permanently attached to poly-SiC handle substrates.
High-performance power devices
SiC-based power semiconductors provide a key solution for improving energy efficiency in electric vehicles (EVs), wind turbines, and more. By reducing device losses, SiC power semiconductors enable higher switching frequencies and voltages while decreasing heat dissipation. With high temperature stability and low carrier concentrations for maximum longevity under harsh environmental conditions; their wide bandgap also protects them from breakdown electric fields.
Historically, major companies like Infineon Technologies, Wolfspeed and Onsemi have dominated the SiC power device market; however, with the rise of electric vehicles (EVs), consumers have increasingly demanded higher-performing components which are smaller and more efficient than conventional silicon components.
Manufacturers need better, more durable SiC power devices in order to meet demand, which requires new types of p-SiC substrates. Engineered substrates for power electronics have become an expanding market due to this trend; engineered substrates combine a poly-SiC handle wafer with mono-SiC top layer as well as thin layer of insulating material and come available in 150mm and 200mm wafer sizes.
These engineered substrates use similar technology as SOI. It consists of bonding a poly-SiC base layer with a mono-SiC top layer; typically this consists of single crystal 4H-SiC bonded to a handle wafer for high volume production, meeting targeted electrical resistivity, thermal conductivity and repeatability specifications.
Electric vehicles
Silicon carbide (SiC) power electronics have long been used in electric vehicles (EVs) to increase efficiency, increase performance, extend driving range and shorten charging times while saving energy while simultaneously lowering greenhouse gas emissions. Due to its superior material properties and wide bandgap semiconductor status, SiC converters play a crucial role in providing energy savings while decreasing greenhouse gas emissions.
However, until recently the growth of the EV market had been limited by limited availability and high costs associated with SiC devices. A major contributor to these costs is their substrate requirements – these must provide suitable seed layers for epitaxial growth as well as reduce resistance in devices; traditional substrates often deposited on insulating wafers often have too much resistance which limits performance of power devices.
SmartSiC substrates provide significant cost savings through single wafer processing and are more reliable and durable than mono-SiC substrates, which may crack during wafer processing. Furthermore, this substrate type is more compatible with high-speed device metallization processes.
Automotive manufacturers and tier suppliers looking for low-resistance SmartSiC should partner with a vertically integrated supplier who can handle every stage of production from growing raw substrate to fabricating finished devices, to ensure high-quality results that eliminate finger pointing between different vendors if any problems arise.
Solar inverters
Solar inverters are used to connect renewable energy sources with the power grid. They convert DC solar energy to AC for use by transmission lines of an electric utility company, eliminating transformers that take up space and energy and saving both money and space. Furthermore, battery storage systems enable more efficient use of renewables while disseminating clean energy more evenly across society.
Silicon (Si) devices such as IGBTs are currently used in PV inverters; however, their performance reaches its limit at higher switching frequencies and suffer from high turn-off losses. To address these issues, manufacturers are increasingly turning to silicon carbide semiconductors (SiC).
SiC FETs boast wide bandgaps that significantly decrease wasted energy during switching events, making them perfect for solar inverters that typically operate at higher frequencies and voltages. Furthermore, their low on-resistance allows them to achieve high efficiencies even at higher switching currents.
As such, they can help reduce the costs associated with solar inverters. A typical 1500V PV string inverter solution from Infineon featuring active neutral point clamped (ANPC) SiC MOSFETs operates at 48kHz and is five to ten percent cheaper on a cost per kW basis than comparable designs using IGBTs.
Wind turbines
Wind turbines harness wind into electricity using a mechanical rotor that turns when activated by airflow. This motion is then transmitted to an electric generator shaft which creates energy. At the top of each tower is located the nacelle that houses additional major components including drive trains, power electronics and an interface to connect with the grid.
Silicon Carbide (SiC) substrates offer power semiconductor devices used in these systems a distinct advantage. Their wide bandgap enables higher voltages to be utilized, which helps decrease equipment loss and increase efficiency while their superior thermal conductivity reduces component sizes and operating temperatures for compact designs with greater energy efficiency.
SiC is driving advances in green energy installations such as solar inverters and wind turbine converters that support global transition to renewable sources of power. These systems are essential to this global effort to move away from fossil fuel dependence.
SiC has long been restricted in its application as power semiconductor material due to availability and cost issues. But now, with several vendors adding capacity during an increasingly challenging wafer-size transition and manufacturers like Soitec offering zero-micropipe products, the future looks bright for SiC power semiconductors.
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