Semiconductor Power Devices and ICs (SPDIC)
Thrust Leader: T. Paul Chow, Rensselaer Polytechnic Institute
The Semiconductor Power Devices and ICs (SPDIC) thrust focuses on the exploration and demonstration of novel integrated power devices and/or ICs in both silicon and wide bandgap semiconductors, such as SiC and GaN, together with the associated device, process, and material technologies necessary for prototype device/IC demonstrations, as well as selective insertion into IPEMs. Over the past couple of years, the thrust emphasis has shifted from discrete or integrated devices to power ICs in silicon. In addition, we have employed commercial and custom foundries of our industrial partners for our prototype device/IC fabrication. This strategy has resulted in decreased lot cycle time, much improved yield on large area devices, facilitated potential technology transfer and enhanced interactions. Besides device/IC demonstrations, we have also identified preliminary reliability assessment of SiC or GaN power devices as a useful effort so as to establish initial performance benchmarks, elucidate possible physical mechanisms of device failure in these new materials, and project long-term robustness in harsh environments.
The SPDIC thrust will continue to pursue power device research in the wide bandgap semiconductors, particularly SiC and GaN, not only because of their potential performance improvement but also because of their material and process maturities and commercial product advances. Instead of exploring conventional device structures, we are examining two types of devices: superjunction devices and MOS-gated bi-directional switching devices. Superjunction devices are interesting because they can increase the maximum usable blocking voltages for unipolar devices and superjunction MOSFETs already have been commercialized in silicon to challenge IGBTs. MOS-gate bi-directional switching devices can provide major technical advances for power circuit topologies. We are examining various vertical and lateral SiC and GaN device structures that are suitable for superjunction device demonstration with selective epi. While heterojunction transistors are popular with GaN FETs, we are pursuing inversion-mode GaN MOSFETs because they can provide normally-off type of operation and allow GaN CMOS as control circuitry.