Silicon carbide on silicon-an ideal material combination for harsh environment sensor applications

Harsh environment conditions, like high temperatures and/or aggressive media, are usually too much for conventional silicon sensor chips. On the one hand, this limits their applicability and shuts a huge field of measurement and regulation problems in the automotive and aerospace area to microsystemic solutions. On the other hand, for the realisation of sensor chips, micromachining techniques are essential and no other material opens nearly as good possibilities in this respect as silicon. One gets out of this dilemma nicely by the combination of silicon with silicon carbide (SiC), a promising semiconductor material for harsh environment applications. The present paper describes the latest developments in the preparation and application of SiC/Si layer systems. In detail, the PECVD preparation of β-SiC on Si and SiO ₂ and the thermal, mechanical, chemical and electronic properties of β-SIC are described. A critical look is taken at the commercial availability of substrates and processes, their costs and their limits, in order to give a realistic picture of future prospects and risks. Application examples in the automotive field (e.g. a combustion pressure sensor) are described and compared to conventional systems