A novel Ccb and Rb reduction technique for high-speed SiGe HBTs

In this paper, we discuss a novel technique to reduce base resistance (R b ) and collector-base capacitance (C cb ) for higher F max in high-speed SiGe HBTs. In order to reduce C cb , we first located the origins of the different components of C cb through AC extraction. Then we utilized scanning capacitance measurements (SCM) to examine the shape of the collector-base depletion. We then propose a method to reduce the extrinsic C cb , namely by using reticle enhancement techniques to print a blocking oxide layer to inhibit boron outdiffusion. An additional benefit was the reduction of R b by reducing the base link resistance.