TEMPERATURE-DEPENDENT INTERFACE REACTIONS AND ELECTRICAL CONTACT PROPERTIES OF TITANIUM ON 6H-SIC

In this study the system Ti-Si-C was investigated in terms of two aspe cts, metallurgical and electrical, in order to understand the formatio n and the properties of Ti electrical contacts on n-type 6H-SiC. For t he metallurgical investigation bulk diffusion couples were prepared fr om monocrystalline 6H-SIC and Ti and annealed between 700 and 1200 deg rees C for different lengths of time. The reaction zones were investig ated using a SEM (secondary electron and backscattered electron images as well as energy-dispersive x-ray analysis). For the investigation o f the electrical properties Ti contacts were sputter-deposited onto GH -SIC wafer stripes and annealed at similar temperatures. The contact p roperties were measured in terms of current-voltage characteristics. W e discovered that, over the whole temperature range investigated, the reaction layer growth follows a parabolic growth law which is thermall y activated. Above 1200 degrees C the diffusion path from SiC to Ti is SiC/Ti3SiC2/Ti5Si3/two-phase Ti5Si3+TiC1-y/Ti5Si3/Ti. The contacts sh ow ohmic behaviour. Between 1000 and 800 degrees C the diffusion path is: SiC/Ti3SiC2/Ti5Si3/two-phase Ti5Si3+TiC1-y/Ti3Si/Ti. The contacts are also ohmic. Below 700 degrees C the diffusion path is SiC/TiC1-y/t wo-phase Ti5Si3 + TiC1-y/Ti3Si/Ti. The contacts are of Schottky type. It is concluded that the phase in contact with the SiC determines the electrical properties of the junction and the possibility of manufactu ring a complete Schottky diode using n-type 6H-SIC and Ti only is demo nstrated.