Today the most advanced technology for monolithically integrating electronic circuitry is the silicon technology. This technology is characterized by very fast increasing integration density and also by an increasing complexity of the circuitry. Beside these items there are growing demands to operate the ICs in harsh environments, especially at elevated temperature in the range above 150xC. Because of the exponential growth of the intrinsic carrier density and hand in hand the growing leakage currents of the devices the conventional bulk silicon technology is reaching their limits. But by the use of SIMOX-substrates (Separation by IMplanted OXygen) the limits of bulk-devices can be overcome with minor changes in a CMOS-process. In this talk I'll present a comparison of bulk- and SIMOX-CMOS device characteristics. I'll show some results about a digital prescaler which has been operated at 250xC for more than 1000 hrs. An outlook will be given about our activities in future.
