10 September/October 2023 | E-Mobility Engineering Cheaper, more efficient MOSFETs IDEAL Semiconductor has developed a technology that can improve the efficiency and cut the cost of power MOSFETs for e-mobility applications (writes Nick Flaherty). The SuperQ process technology can also be applied to SiC MOSFETs and GaN transistors in the future, said Mark Granahan, CEO and founder of iDEAL Semiconductor. SuperQ uses a combination of new dielectric materials, etching and atomic layer deposition (ALD) to improve the performance of power devices for motor control. The process enables a much lower specific onresistance (RSP) for a much lower onresistance in the device, which in turn improves the switching performance as the die is smaller. iDEAL aims to produce transistors up to 850 V, as the same process can be used for devices from 60 to 850 V rather than needing multiple technologies to cover the voltage range. “Our technology gives a voltage blocking of 19-20 V/µm, a 30% improvement over other processes, so our epitaxy is much thinner,” said Granahan. “The conduction area is also greatly expanded so we have more area, and that improves the RSP. The larger conduction area and higher doping concentration deliver an effective highvoltage blocking technique.” Using chip-making tools from the CMOS world also makes the process simpler and cheaper. The company is using the process to build its own 650-800 V MOSFETs with foundry partners including Polar Semiconductor, although the devices are not automotive-qualified. However, they can be used for other e-mobility platforms such as e-bikes. “Rather than epitaxial implant with over 18 masks and long process times, or trench and refill with 14 masks, our etch and ALD deposition has around 10 masks so our capital cost is low and the process is shorter,” said Granahan. “Our MOSFET structure is very simple. The mask count is about 10-11, and that plays to the reliability of the device. Reliability testing has proven the technology, and it shows that the breakdown voltage and leakage current are stable over time.” SuperQ is also being used to boost the switching frequency of designs. “The structure of the device is optimised for fast switching,” said Granahan. “We can easily break 150 kHz, which is the upper range of power designs.” As for SuperQ’s application to GaN and SiC as well as silicon, Granahan said, “Our perspective is that SiC and GaN are great power materials but they have a lot of fundamental issues in manufacturability that the industry has yet to work through.” POWER ELECTRONICS Quantum jump speeds FC designs BMW and Airbus are using a quantum computer to improve the design of hydrogen fuel cells (writes Nick Flaherty). The two are working with quantum computing company Quantinuum on a design flow that combines quantum and classical techniques to speed up research. Quantinuum uses a Honeywell-developed quantum computer based on trapped ions that can simulate the chemical reactions of catalysts in the fuel cells. The three companies are modelling the oxygen reduction reaction (ORR) on the surface of a platinum-based catalyst to improve the performance of proton exchange membrane fuel cell designs for electric cars, trucks and aircraft. ORR is the chemical reaction in the process that converts hydrogen and oxygen into water and electricity, and it limits the efficiency of the process. It is relatively slow and requires a lot of platinum catalyst, so there is great interest and value in better understanding the underlying mechanisms involved in the reaction. This design of new catalysts can shorten the development time, but owing to the complexity of the ORR’s potential energy landscape, atomiclevel modelling of the process is challenging. The catalyst materials can also exhibit strong electronic correlations, which cannot be accurately described with methods such as Density Functional Theory (DFT). DFT modelling is seen as too costly and lengthy to perform with classical techniques but is suitable for algorithms that run on quantum computers. FUEL CELLS The SuperQ process improves the on-resistance of power devices for motor control
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