Reliability of SiC Digital Telemetry Circuits on AlN Substrate

In this work, two silicon carbide based integrated circuits (frequency counter and timing generator) have been designed and fabricated as building blocks of a digital telemetry module for the purpose of sensing and transmitting pressure measurements from a geothermal well at temperatures up to 300°C. The frequency counter consists of one 4-bit counter, one 4-bit shift register, and one buffer. The timing generator contains an 8-bit counter, a D-flipflop, and some dedicated logic gates to generate timing pulses for the two channel frequency counter. These dies were flip-chip bonded to patterned gold thin-film aluminum nitride substrate circuit boards and tested for functionality in a lab oven at 300°C and prove to operate continuously for more than 1000 hours. Also the boards were subjected to random vibration at 20G RMS and also mechanical shock at 215G at 300°C and remained operational after 8 hours of vibration and 1000 shocks.