Silicon Carbide device technology is now evolving from a pure vision to a r
eal alternative to silicon devices. The feasibility of SIC devices has been
shown for many different types of devices, the development of a working pr
oduction technology has started, yield, reliability and costs now being the
key issues. At present the high substrate prices keep the manufacturing co
sts of SiC high, making it very difficult to enter the device market with S
IC on economic terms. Prime applications are those for which SIC offers sub
stantial benefits or even a technological breakthrough on the system level.
The main application is power conversion when the latest development effor
ts on silicon based power switches (e.g. IGBT) allow utilisation of much hi
gher switching frequencies, putting very high demands on the free wheeling
diode. The system performance is to a large extent limited by the diode rec
overy charge-a major source of switching losses. Depending on the voltage r
ange, different device concepts are of interest: In the lower voltage range
the junction-barrier controlled Schottky (JBS) device is a promising candi
date while at voltages beyond 2.5 kV the PIN diodes is the device of choice
. Different system requirements-e.g. surge current capability-make the PIN
junction superior to a Schottky device for certain applications. With progr
ess in material and technology development the 'world's best' result is bec
oming less and less important and reproducibility is the issue. Failure ana
lysis of defective devices needs to be established with a high number of su
bstrate defects being still an obstacle in SIG. High leakage/soft reverse c
haracteristics are often encountered and can usually be attributed to local
ised defects. It is important to identify their origin and to separate proc
ess-induced defects from those already present in the epilayer or substrate
. In order to use the high power handling capability of SIC reduction of ma
rgins (e.g. in epilayer thickness and doping) is necessary. This requires n
arrow bandwidth of process and material variations. For paralleling of SiC
devices equal current sharing under static and dynamic conditions is a fund
amental requirement from the system side. Top-down calculation gives materi
al specifications, which the supplier has to meet. (C) 1999 Elsevier Scienc
e S.A. All rights reserved.