Extreme Environment SiC Integrated Circuits

Silicon Carbide (SiC) is by now well established in use for commercial high voltage electronic switching devices [1]. The high critical field for breakdown is taken advantage of to increase the doping level and reduce the width of the blocking region; thereby reducing the on-resistance by up to a factor of 400 in comparison to silicon high voltage switches [1]. It is also well known that the wide bandgap leads to a strong reduction in intrinsic carrier concentration, so that high temperature operation is possible [2]. Thermal generation of carriers in silicon leads to junction leakage currents and failure, even for silicon on insulator (SOI), limiting operating temperatures to around 300 °C. However, SiC devices and integrated circuits have been operated even in the range of 500 – 800 °C or higher [3-5]. After the first demonstrations of digital and analog integrated circuits for extreme temperatures, the sights have been set on mixed signal systems capable of signal amplification and conversion, which demands process design kits and higher levels of integration [6]. Another extreme environment that SiC electronics has been investigated within is radiation hard environments such as aerospace and nuclear energy. Whereas results are mixed for high voltage devices, for low voltage integrated circuits SiC is certainly promising [7]. There are many challenges when extreme environments are targeted for integrated circuits, which will be included in this presentation:

1.  selection of insulating and conducting materials that have as good tolerance as SiC to the extreme environments, specifically the high temperatures
2.  design of process technology for SiC integrated circuits including contacts, isolation, interconnects and passive devices
3.  simulation models of transistors and passive devices over the wide temperature range intended for the integrated circuits
4.  circuit designs for both digital and analog integrated circuits operative over the entire temperature range
5.  process design kits including layout vs schematic (LVS) check

Other challenges, which will not be covered in any detail, include packaging and long term reliability. However, these are key technologies for the application areas intended. Experimental results from several batches over seven years in an in-house bipolar integrated circuit technology will be shown and discussed [4-7].

Coffee and cake will be available for the first 30 attendees at 15:00, warmly welcome!
 

[1] T. Kimoto and J. A. Cooper, Fundamentals of Silicon Carbide Technology (Wiley, New York, 2014).
[2] J. D. Cressler and H. A. Mantooth (eds), Extreme Environment Electronics (CRC Press, Boca Raton, FL, 2013).
[3] P. G. Neudeck et al, IEEE Electron Device Letters, 38, 1082 (2017).
[4] C.-M. Zetterling et al, Semiconductor Science and Technology, 32, 034002 (2017).
[5] C.-M. Zetterling, MRS Bulletin, 40, 431 (2015).
[6] Y. Tian and C.-M. Zetterling, IEEE Transactions on Electron Devices, 64, 2782 (2017).
[7] S. S. Suvanam et al, IEEE Transactions on Nuclear Science, 64, 852 (2017).