Silicon Fights Back in Power

After seven years of development, iDeal Semiconductor has started shipping its first silicon power devices based on a new architecture. The first 150V power MOSFETs are shipping with an on-resistance of 6.4mΩ, while 200V devices are now sampling. Devices are planned up to 400V for more efficient AI datacentre power supplies.

The devices can increase the switching frequency of power supplies to reduce the size, or reduce the losses, Mark Granahan, CEO of Ideal Semiconductor tells eeNews Europe. This aims to take on silicon carbide (SiC) and gallium nitride (GaN) with lower cost and lower losses.

The parts are being made on a CMOS process by Polar Semiconductor in the US. “We developed this platform in the US which at the time was outlandish as most of the foundry is in Asia and it did take ups a substantial amount of time to develop a brand new process technology as well as the device architecture with a new foundry,” said Granahan. “Polar Semiconductor are dramatically expanding their capacity on 200mm silicon wafers.”

The SuperQ power silicon technology, which is a combination of Hexfet and Superjunction topologies is based on CMOS process flows with additional, modified equipment and a lower number of masks, typically around 10.

“As the end of the day we have been very innovative in how we identify the opportunity to dramatically improve silicon, it starts out cheaper, it has less defects, the temperatures are a lot lower, and we have the proven reliability and the manufacturing capacity so we can take advantage of depreciated tools. Add to that the simplicity of our technology, we have a very optimised process,” he said.

“We use a high aspect ratio trench and depositing a thin film to charge compensate the structure to combine the benefits of the superjunction and the hexfet so we can get to 95% of the structure used for conduction and only 5% for voltage blocking, increasing the blocking by 30 to 40% at 20V/um.”

“That simplicity gives us benefits in cost and cycle time, we can build it in any fab in less than three weeks,” he said. “There are a few tools that are unique to our process. The unique tools we are using with the exception of one, are common in CMOS, but not in power. The tool for the high aspect ratio deep trench is unique and we have worked with a mainstream tool vendor on a volume production tool and we work with them to add unique capabilities.”

The company is also using standard packaging such as top cooled leadless TOLL and D2PAK which allows for second sourcing and the company is also working on a four lead Kelvin package for lower on-resistance.

The silicon power devices are qualified at 175 °C and 100% tested which allows for AECQ automotive qualification. “The technology is ready to go,” said Granahan.

The first product in iDeal’s 150 V MOSFET series, iS15M7R1S1C, is a 6.4 mΩ MOSFET. It is available immediately in a 5 x 6 mm PDFN package. The SMT package includes exposed leads to simplify assembly and improve board level reliability.

The 200 V family includes the iS20M6R1S1T, a 6.1 mΩ MOSFET in a 11.5 x 9.7 mm TOLL package. This has an RDSon of 6.1 mΩ, which is 10% lower than the current industry leader and 36% lower than the next best competitor. The company is also sampling 200 V MOSFETs in TOLL, TO-220, D2PAK-7L and PDFN packages.

“We have a very clear roadmap to continue to improve the performance and cost of the device for the next 15 to 20 years,” said Granahan.