Structure of Directly Bonded Interfaces Between Si and SiC

Abstract

A Si-on-SiC wafer in which the Si wafer is directly bonded to the semi-insulating single-crystal 6H-SiC without an intermediate layer was developed. A remarkable improvement in the heat-dissipation performance due to the high thermal conductivity of SiC was demonstrated for Si metal oxide semiconductor field-effect transistors fabricated on the bonded wafers. In transmission electron microscopy (TEM), linear defects similar to misfit dislocations with a density of 2-6 × 107 lines/cm−2 were observed in plan-view TEM images of the Si/SiC interfaces. Comparison between Si(001)/6H-SiC(0001) and Si(111)/6H-SiC(0001) interfaces implies that the linear defects were formed on the Si side of the Si/SiC interface. Disordered Si layers with thicknesses of several atomic layers were observed in the cross-sectional TEM images, and the thickness is minimized at an annealing temperature of 1000{degree sign}C. The trap density at the interface was determined by admittance spectroscopy to be ~1 × 1011 cm−2eV−1 at most.