Concept of vertical bipolar transistor with lateral drift region, applied to high voltage SiGe HBT

We demonstrate the increase of available collector emitter voltage of integrated vertical bipolar transistors by means of an additional lateral drift region introduced between sub collector and collector contact region. The chosen approach enables the fabrication of high voltage bipolar transistors for RF power applications alternatively to the construction of deep collector wells in vertical direction by an extra epitaxy step or ion implantation with very high energy. The new approach was verified with a modified standard SiGe:C HBT integrated in a high performance BiCMOS process. After introduction of an additional lateral drift region with a length of 1.2 μm BVCE0 of the HBT has increased from 7 V to 18 V.