SOI Microelectronics for harsh environment
in aero-space applications

Onno W. Purbo

owpurbo@sunee.waterloo.edu
yc1dav@ve3.yc1dav.ampr.org
Department of Electrical and Computer Engineering
University of Waterloo
Waterloo, Ontario
CANADA N2L 3G1
ph: [519] 885-1211 x 2872
FAX: [519] 746-3077

on leave from:
Department of Electrical Engineering and
Inter University Center on Microelectronics
Institute of Technology Bandung
Bandung 40132
INDONESIA

	In fly by wire implemented in modern aircrafts, a significant task has been put on the on-board computers and other electronic devices to assist the pilot in handling an airplane towards its destinations. Reliability is important as these electronic equipments will unfortunately find itself in extreme operation conditions such as extreme temperature or even high Gamma radiation. In this work, we report on our preliminary results of a comparative study of the Zone-Melting Recrystallized (ZMR) Silicon-on-Insulator (SOI) technology and the conventional Silicon technology in harsh environment. Polysilicon emitter bipolar transistor (PET), which serves as a candidate in high-speed VLSI circuits, was used as a vehicle to compare the technological performances. The higher defect density in ZMR-SOI material seems to lowering the process yield by only 10%. Despite the use of similar fabrication steps, ZMR-SOI PETs have 30% higher current gain due to the lower base current caused by a slightly thicker interfacial oxide thickness between poly and mono Silicon interface. Furthermore, the thicker interfacial oxide is found to increase the parasitic emitter resistance which may slightly degrade the high frequency performance. Our simulations indicate 1-2 GHz frequency of operation of the PETs may be attained. Using a Low-Temperature Micro Probe (LTMP) in the range of 85-400K, we found the leakage current in ZMR-SOI PETs is lower than that of bulk-Si PETs. Furthermore, ZMR-SOI PETs is found to have lower the recombination current. Some preliminary measurement of PET under long Gamma radiation exposure with total dose of 20-100 KRad indicate an increase in the trap density in the space charge region which increases the base recombination current. Despite a slight degradation in speed, ZMR-SOI PETs are found to be more reliable in harsh environment for aero-space applications.