The Effects of Proton Irradiation on the Lateral and Vertical Scaling of UHV/CVD SiGe HBT BiCMOS Technology

We present the first experimental results of the effects of 63 MeV proton irradiation on both the lateral and vertical scaling properties of SiGe HBT BiCMOS technology. Three distinct generations of (unhardened) SiGe technology are examined. The first generation SiGe HBTs experience very minor degradation in current gain at proton fluence as high as 2 x [10.sup.13] p/[cm.sup.2]. The second and third generations SiGe HBTs, however, show 60-70% degradation in current gain under similar conditions, suggesting that emitter-base spacer optimization may be required as the technology is scaled. Si nFETs from the first generation SiGe BiCMOS technology are only hard to about 40 krad equivalent gamma dose, and are limited by drain-to-source leakage along the shallow trench edge. The second generation Si nFETs, however, improve with scaling since the shallow trench is thinned, and can withstand up to 150 krad of equivalent dose.