Current status and future trends of SiGeBiCMOS technology

The silicon germanium (Site) heterojunction bipolar transistor (HBT) market place covers a wide range of products and product requirements, particularl y when combined with CMOS in a BiCMOS technology. A new base integration ap proach is presented which decouples the structural and thermal features of the HBT from the CMOS. The trend is to use this approach for future SiGe te chnologies for easier migration to advanced CMOS technology generations. La teral and vertical scaling are used to achieve smaller and faster SiGe HBT devices with greatly increased current densities. Improving both the f(T) a nd f(MAX) will be a significant challenge as the collector and base dopant concentrations are increased. The increasing current densities of the SiGe HBT will put more emphasis on interconnects as a key factor in limiting tra nsistor layout. Capacitors and Inductors are two very important passives th at must improve with each generation. The trend toward increasing capacitan ce in polysilicon-insulator-silicon (MOSCAP), polysilicon-insulator-polysil icon (Poly-Poly), and metal-insulator-metal (MIM) capacitors is discussed. The trend in VLSI interconnections toward thinner interlevel dielectrics an d metallization layers is counter to the requirements of high Q inductors, potentially requiring a custom last metallization layer.