News: Microelectronics
22 July 2024
UK–Swiss joint funding for project to develop SiC power MOSFET gate technology using ALD oxides
After the UK and Switzerland governments signed a memorandum of understanding in 2022 to harness collective strengths of the two countries, followed recently by a first joint funding call, 26 projects to enhance UK and Swiss collaborations and capabilities in emerging fields of technology have been selected to receive total funding of £7.8m from Innovate UK (which provides funding and support for business innovation as part of UK Research and Innovation) and CHF9.1m from the Swiss innovation agency Innosuisse.
One of the projects involves Zurich-based Hitachi Energy Switzerland collaborating with UK-based Oxford Instruments Plasma Technology (OIPT) and the University of Warwick (UoW).
Hitachi Energy Switzerland has a track record of developing automotive-grade silicon carbide (SiC) power metal-oxide-semiconductor field-effect transistors (MOSFETs), with a reputation for products with novel MOS interfaces. OIPT has developed a novel oxide deposition process that uses a remote plasma source in a commercial atomic layer deposition (ALD) system. It has been demonstrated that this process is suitable for the formation of gate oxides in wide-bandgap semiconductors. A research team at the University of Warwick recently developed an ALD silicon dioxide (SiO2) deposition process on SiC that has the potential to be commercialized. The project will bring together the three groups and their corresponding expertise to demonstrate the potential of ALD oxides in the formation of electric vehicle (EV)-grade 1.2kV SiC MOSFETs.
The aim of the project is to address one of the most pressing issues in the adaptation of this technique by fundamentally changing the way of forming a crucial part of the device, the gate oxide. Conventional dielectric and SiC interfaces suffer from a high density of defect states, hampering the further uptake of this technology. The proof-of-concept project will demonstrate the viability and advantages of utilizing ALD-deposited oxides (SiO2 and high-k dielectrics such as aluminium oxide, Al2O3) in a commercial SiC MOSFET device.
Key aims of the project include:
- the first demonstration of a commercially relevant planar 1.2kV SiC MOSFET that contains OIPT’s remote plasma ALD-deposited SiO2 and high-k dielectric (for example Al2O3) gate oxides;
- demonstration of the interface quality (for example, high channel mobilities due to a low density of interface traps) in these structures through the extraction of key performance indicators such as specific on-resistance or channel mobilities;
- demonstration of process benefits by benchmarking with existing commercial products;
- long-term reliability testing on the demonstrator MOSFETs will demonstrate whether the ALD oxides remain stable over the lifetime of a commercial automotive semiconductor product;
- integration of the novel ALD oxidation process into a research-grade trench MOS capacitor and trench MOSFET structure.
