Commercial SiC Power Electronics

The current power semiconductor market ($10bn) is dominated by silicon. The performance of which has improved steadily over the past 20 years, but has now reached the stage where its fundamental material properties limit the capability and efficiency of power semiconductor systems. The superior material properties of Silicon Carbide (SiC) have been recognised as the way forward yet to date SiC transistors have very poor performance and production costs are prohibitive. This proof of concept proposal is to prove Anvil Semiconductor’s solutions to the two main issues preventing SiC taking its potential market share ($2.6bn): the cost of the substrate and the ability to produce good quality gate oxides (and thus produce good quality transistors). This work enables the development of low cost Silicon Carbide (SiC) power electronic components suitable for mass market applications, the first of which are electric vehicles and power inverters for domestic photovoltaics. Together these are predicted to account for 60% of the potential SiC market (2019). The current generation of SiC components based on the hexagonal form (4H-SiC) are inherently expensive; a 100mm wafer of 4H-SiC costs ~£1,000 compared to ~ £20 for a Si wafer. Further it is likely that 100mm will be the main 4H-SiC wafer diameter for at least the next six years- restricting size based economies of scale. Thus 4H-SiC components are unlikely to be viable in cost sensitive applications. A low cost alternative route using a thin SiC layer deposited on a Si wafer has been demonstrated on 150mm wafers and provides a route to even larger diameters (3C-SiC/Si). This has technical challenges but Anvil Semiconductors has some key IP which it needs to demonstrate has no technological barriers to prevent it making the components needed by system builders. An ideal application of SiC is the drive inverter for electric vehicles because of its improved power efficiency, increased robustness in high temperature environments and importantly the dramatic reduction of size/mass of the system. Yole (Appendix A) show that the use of SiC components instead of Si would result in an overall system cost increase of $31; not an acceptable solution. However with the lower cost version of SiC proposed here, there would be a system saving of ~$100. This would enable car designers to take advantage of the space, energy and robustness savings of SiC. Another application for low cost SiC devices is the power conversion in domestic scale (~5kW) photovoltaic panels. Although current Si-based inverters are very efficient (97%), they are bulky and expensive, and have slow switching speeds leading to the need for physically large passive components and heatsinks. SiC components will reduce the size and costs of the capacitors, inductors and system cooling needed. However, a component technology with similar costs to Si is essential in order to achieve an overall reduction in system cost, ie 3C-SiC/Si.