TranSiC claims first commercial SiC switch
TranSiC has launched the first normally-off SiC transistor to hit the market, and anticipates device qualification within nine months.
The company says that more than 20 different customers are currently interested in its BitSiC1206 bipolar junction transistors (BJTs), and it is in the process of selecting one to be a qualification partner.
According to TranSiC s CEO, Bo Hammarlund, the partner is likely to come from the automotive industry. This partner will presumably receive the majority of the 5000 or so packaged BJTs that Kista, Sweden, based TranSiC is planning to make at the nearby Electrum lab in 2008.
“We have customers all over the world right now asking for components,” Hammarlund said. “Because we are still a small company, my problem is more to select the ones that we can actually support.”
Such transistors are expected to improve upon high-power silicon devices, for example by reducing power loss during switching, and subsequently trigger an expansion of the SiC device market.
“This could be a real breakthrough for the SiC industry,” said Philippe Roussel, an analyst at Yole Développement who focuses on power electronics. “We need a switch or there will be no market at all, only Schottky diodes.”
“There is nothing else available normally off for high voltages and high temperatures of 225°C-plus today,” Hammarlund said.
Surprises and packages
The BitSiC1206 is making its presence felt in a number of formats. TranSiC recently started providing engineering samples of bare BJT chips, and is now providing the same device in a packaged format acceptable to a wider range of customers.
Early next year the company will provide the BitSiC1206 in one package capable of handling 250°C and in another package, bundled with a Schottky diode. TranSiC is also working on upgrading the 1200 V, 6 A device to handle 20 A currents.
“We have some very encouraging results over 3000V but that's too early right now,” Hammarlund added. He also said that, while full reliability testing is yet to be performed, high reverse voltage testing “looks good” at room temperature with leakage currents low and stable at 50 nA.
The company is also yet to finalize the wafer size it will use in its manufacturing process, although Electrum's production line can go up to 4-inch wafers.
The recent progress in high-quality “zero-micropipe” substrates to 4-inch diameters (see related stories) has surprised TranSiC, Hammarlund says. The company is now in the process of measuring the performance of devices made on these larger wafers.
With this announcement TranSiC appears to have trumped larger firms like Cree who are also working in this area. However, Roussel was keen to see a full set of data for the BJT, to be fully confident that it is a breakthrough.
“We need to have a mean-time-to-failure specification and reliability data,” he said. “Otherwise this could be like Rohm, who announced a SiC MOSFET [another normally-off transistor] two or three years ago, but it never appeared.”
