Neutron radiation tolerance of advanced UHV/CVD SiGe HBT BiCMOS technology

The effects of 1.0 MeV neutron irradiation on both SiGe heterojunction bipolar transistors (HBTs) and Si CMOS transistors from an advanced ultra high vacuum chemical vapour deposition (UHV/CVD) SiGe BiCMOS technology are examined for the first time over the temperature range of 300 K to 84 K. Results at 300 K indicate that this SiGe technology is robust with respect to neutron radiation. At fluences as high as 10¹⁵ n/cm² (1.0 MeV equivalent) the devices exhibited a degradation of less than 30% in peak current gain. The SiGe HBTs maintain a current gain of 60 after 10¹⁵ n/cm ² at 84 K, compared to the Si BJT which degrades with cooling to a current gain of 20 at 84 K. The cutoff frequencies of both the Si and SiGe transistors are unaffected by neutron irradiation, and only a slight degradation in the maximum oscillation frequency of the transistors was observed