The Research of Temperature characteristics of SiGe HBT and the Reliability under Thermal Stress

The temperature characteristics of SiGe HBT and its reliability under thermal stress are studied. The experiment results indicate that the current gain at 77 K is much larger than the one at 290 K. And there is a critical value of I_C, which is 2times10^-4A. Over this value, the gain increases with the decrease of the temperature. But below the value, the gain drops with the decrease of the temperature. The current ideal factor is smaller than 2 when the temperature is over 193 K, but larger than 2 at 193 K or below. Besides this, the thermal stress experiments for the base-emitter junction were taken under 100degC and 150degC, and the stress time was 90 hours and 30 hours, respectively. The experiment results indicate that the device characteristic parameters fluctuate under the different thermal stress conditions. The annealing and degeneration play the collective role in the characteristics fluctuating under the thermal stress condition.