Will it be the largest silicon carbide materials factory in the world?


This article is part of the TechXchange: FeedDesign.

Wolfspeed will invest up to $5 billion to build what it claims is the world’s largest silicon carbide (SiC) materials factory, in a bid to bolster its supply of a key semiconductor for the future of electric vehicles (EV).

The company said the new facility will be located on the outskirts of Raleigh, North Carolina, near its headquarters in Research Triangle Park.

The new plant will help the company meet the growing demand for SiC wafers over the next few years, both internally and externally. Power MOSFETs forged from SiC have special physical properties that allow them to pump more power and dissipate less heat when regulating or converting electricity. This results in better power density and system-level efficiency, especially at higher voltages.

The company is struggling to keep up with an increase in demand for power MOSFETs and other SiC-based chips, largely due to a lack of raw materials and capacity in facilities capable of processing them in chips.

Wolfspeed President and CEO Gregg Lowe said, “Demand for our products continues to grow at a rapid rate and the industry continues to be constrained in supply. The expansion of our materials production will strengthen our market leadership and allow us to better meet the growing needs of our customers.

The first phase of construction will be completed in 2024 at a cost of around $2 billion, the company said. Wolfspeed will add more capacity if needed in a second phase expected to be completed in 2030.

The new facility could eventually occupy more than one million square feet on the 450-acre site, creating 1,800 jobs by 2030. According to Wolfspeed, its investment in the site could reach $5 billion.

In addition to electric vehicles, SiC-based electric devices are also considered essential building blocks for photovoltaic (PV) inverters for solar panels, fast charging stations, high-voltage industrial motor drives and railway infrastructure. .

Material differences

The potential of SiC in the world of power electronics is largely attributed to the material itself.

SiC is a semiconductor with a wide bandgap, a property that allows it to tolerate higher breakdown voltages (thousands of volts or about 10 times what a standard silicon chip can withstand) and higher temperatures (over 500°C in some cases) than silicon MOSFETs. and IGBTs that have dominated for decades.

SiC-based power MOSFETs are alternatives to IGBTs at higher voltages, due to their reduced turn-on and turn-off losses in switches. This contributes to its superior power efficiency compared to silicon chips.

SiC offers better on-state resistance (RDS (enabled)) at high voltage levels, resulting in lower power loss and higher current density, and resulting in less heat when regulating and converting power from one level to another.

Switching speeds are also faster than the silicon MOSFETs and IGBTs they replace. This feature allows you to surround the immediate power stage with smaller transforms and other passives. Combined with improved energy efficiency, they can help reduce the weight and bulk of power supplies.

With its ability to handle high voltages efficiently and tolerate intense heat, SiC is gaining traction as more electric cars hit the road. Tesla pioneered the use of SiC chips in a mass-produced vehicle. Today, other major automakers are following in its footsteps.

At the beginning of this year, Wolfspeed has struck a deal to supply US auto giant GM with SiC devices that will control the power electronics embedded in future electric vehicle models.

Each EV contains several major power building blocks. But many want to use SiC in the inverter that converts DC from the battery to AC to power the electric motor turning the wheels, where even small gains in energy efficiency pay huge dividends.

In turn, it reduces power losses for power electronics and thus extends the range of electric vehicles. As an alternative, automakers could build electric vehicles with smaller, cheaper batteries without sacrificing range.

These chips are also used for the on-board charger (OBC) of electric vehicles. Their power-saving capabilities translate to faster charging rates because the chips can transfer much more electricity.

Incredibly hard

Wolfspeed’s new facility will grow SiC ingots and process them into 200mm wafers, which are 1.7 times larger than the 150mm wafers that have long been the dominant format for SiC.

The larger form factor translates to more power semiconductors per wafer and in doing so reduces the higher costs per device for SiC MOSFETs. One of the main challenges for the company is ensuring that the higher system-level efficiency possible with SiC chips outweighs the higher cost of manufacturing them.

Despite its valuable power handling properties, SiC is one of the hardest materials in the world and handling it is a challenge. To grow the ingots it slices and turns into chips, Wolfspeed uses custom ovens that heat the raw material to several thousand degrees, so hot they vaporize the raw silicon and carbon used in the process.

The compound fuses around a so-called “seed” which forms a cylindrical bar of SiC – an entire single crystal – called a ball. The ingot is then sliced ​​into mirror-polished discs to remove as many irregularities and impurities as possible. It is far from a simple procedure: the hardness and brittleness of silicon carbide means that it is more difficult to polish the surface of the insert without damaging it.

The company presents itself as the world’s largest supplier of SiC, responsible for approximately 60% of global production. The expansion, says Wolfspeed, will increase its ability to produce the raw material tenfold.

Federal funding?

These wafers will be used to supply the recently completed Wolfspeed fab in upstate New York, which opened earlier this year as the first in the world capable of deploying SiC devices with 200 wafers. mm. Customer deliveries of SiC-based devices from the Mohawk Valley plant are expected to begin before the end of this year.

Factory pads will likely be used primarily for Wolfspeed’s internal manufacturing needs. But the company also has supply agreements with external partners such as STMicroelectronics.

The announcement comes as the United States prepares to distribute tens of billions in grants, grants and other incentives under the recently passed CHIPS and Science Act signed into law by President Biden last month.

Wolfspeed is set to earn a share of some $39 billion in manufacturing-related subsidies and a 25% investment tax credit on new US factories under the legislation, also known as the CHIPS+ Act. She hopes to seek and obtain the funding made possible by the bill to accelerate the construction and deployment of the plant.

While it remains to be seen how much help it receives from the United States, Wolfspeed’s build plan in North Carolina likely boiled down to non-federal incentives. To support the development of the first phase of the facilities, Wolfspeed said it has landed $1 billion in incentives from state, county and local governments.

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