Design and Fabrication of Silicon-on-Silicon-Carbide Substrates and Power Devices for Space Applications

P.M Gammon,G Camuso,P.A Mawby,V Kilchytska,V Pathirana,C.W Chan,D Flandre,T Trajkovic,F Gity,K Ben Ali,L Fan,J.W Gardner

doi:10.1051/e3sconf/20171612003

Abstract

A new generation of power electronic semiconductor devices are being developed for the benefit of space and terrestrial harsh-environment applications. 200-600 V lateral transistors and diodes are being fabricated in a thin layer of silicon (Si) wafer bonded to silicon carbide (SiC). This novel silicon-on-silicon-carbide (Si/SiC) substrate solution promises to combine the benefits of silicon-on-insulator (SOI) technology (i.e device confinement, radiation tolerance, high and low temperature performance) with that of SiC (i.e. high thermal conductivity, radiation hardness, high temperature performance). Details of a process are given that produces thin films of silicon 1, 2 and 5 μm thick on semi-insulating 4H-SiC. Simulations of the hybrid Si/SiC substrate show that the high thermal conductivity of the SiC offers a junction-to-case temperature ca. 4× less that an equivalent SOI device; reducing the effects of self-heating, and allowing much greater power density. Extensive electrical simulations are used to optimise a 600 V laterally diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET) implemented entirely within the silicon thin film, and highlight the differences between Si/SiC and SOI solutions.

Highlights

Space is an expanding and changing market for power electronics
Ten years on from [4], wide bandgap semiconductors such as silicon carbide (SiC) and gallium nitride [8] are yet to make a significant impact on the space power market, though SiC Schottky diodes are being integrated into the solar inverter solution on BepiColombo [9]
We introduce a new generation of lateral power electronic semiconductor devices that are being developed for the benefit of both space and terrestrial harsh-environment applications

Summary

Introduction

Space is an expanding and changing market for power electronics. This is in part due to the rise of all electric propulsion systems for fine orbit control, as demonstrated for ESA mission GOCE, where a 600W/1.5kV QinetiQ T5 ion thruster [1] has been employed, and more widely for the orbit control of Geostationary Earth Orbit (GEO) telecommunications satellites. The silicon-on-silicon carbide (Si/SiC) semiconductor substrate will attempt to improve upon current SOI technology by removing the buried oxide (BOX) layer that prevents efficient heat removal and causes poor TID tolerance. We will present the results of currently on-going device fabrication trials that are producing Si/SiC power devices in this substrate, for space applications.

Results

Conclusion