Silicon carbide (SiC) chips are on a roll, largely due to their ability to offer greater switching efficiency and power density for a wide swath of designs ranging from electric vehicles (EVs) to renewable energy to motor drives.
Here's a look at some of the recent moves from major corporations including Microchip, ROHM, STMicroelectronics, and Infineon that act as evidence that this semiconductor is serious business.
Microchip is the latest IC supplier to announce SiC devices for EV systems such as external charging stations, onboard chargers, DC-DC converters, and powertrain and traction control solutions. The Chandler, Arizona-based chipmaker came by its wide-bandgap technology assets through its 2018 purchase of Microsemi. This month, Microchip unveiled a new suite of products including 700 V SiC MOSFETs and 700 V and 1200 V SiC Schottky barrier diodes (SBDs).
Image from Microchip
These SiC chips—MOSFETs and SBDs—offer more efficient switching at higher frequencies and perform 20 percent better in ruggedness tests like Unclamped Inductive Switching (UIS) than competing SiC diodes. The UIS ruggedness test measures how well devices withstand degradation or premature failure under avalanche conditions that occur when a voltage spike exceeds the device’s breakdown voltage.
Microchip also claims that its SiC MOSFETs demonstrate better gate oxide shielding and channel integrity with little lifetime degradation even after 100,000 cycles of Repetitive UIS (RUIS) testing.
Likewise, ROHM Semiconductor has released 10 new automotive-grade SiC MOSFETs. ROHM is targeting its SCT3xxxxxHR series of SiC MOSFETs at onboard chargers and DC/DC converters. ROHM was the first chipmaker to manufacture the SiC MOSFETs in December 2010. Later, in 2012, it started supplying Schottky barrier diodes for onboard chargers.
ROHM has also announced the development of a 1700 V/250 A rated SiC power module that incorporates the company’s SiC MOSFETs and SiC Schottky barrier diodes; it optimizes the internal structure to reduce ON resistance by 10 percent compared to other SiC products in this class.
ROHM is targeting the BSM250D17P2E004 modules at inverter and converter applications in outdoor power generation systems and industrial high-voltage power supplies. The Japanese chipmaker claims to have used new construction methods and coating materials to prevent dielectric breakdown and suppress increases in leakage current. That, in turn, ensures reliability in high-voltage and high-temperature environments.
Apart from the availability of new SiC products, what’s most notable is how large chipmakers are acquiring the SiC wafer assets in anticipation of future demands. Here are a couple of examples showing how these acquisitions are helping expand the SiC ecosystem.
SiC Wafers: Develop or Acquire?
STMicroelectronics, for instance, has acquired a majority stack in Swedish SiC wafer manufacturer Norstel, which develops and manufactures advanced 150 mm SiC bare and epitaxial wafers. Norstel was founded in 2005 as a spinoff of Linköping University.
Just a month earlier, in January 2019, STMicro signed a multi-year deal for SiC wafer supply with Wolfspeed. Wolfspeed will supply ST with 150 mm silicon carbide bare and epitaxial wafers.
Like ST, another chipmaker proactive in the development of SiC-based chips and modules for automotive and industrial designs is Infineon Technologies. In November 2018, the German chipmaker announced the acquisition of a Dresden-based startup Siltectra.
Siltectra’s technology splits crystalline materials with minimal loss of material compared to common sawing technologies. Screenshot from Siltectra
Siltectra has developed "Cold Split" technology that processes crystal material efficiently and with minimal loss of material. Infineon plans to employ the Cold Split technology to split SiC wafers and double the number of chips on a wafer.
These activities in the design and wafer realms show SiC technology’s accelerated evolution and adoption. The SiC-based chips, modules and power stacks are now serving a variety of applications such as xEV, xEV charging infrastructure, PFC power supply, PV, uninterrupted power supply (UPS), motor drives, wind, and rail.
What are your views on the rise of SiC? Do you have experience designing EV systems? Share your thoughts in the comments below.
Featured image used courtesy of Microchip.