Horizontal Current Bipolar Transistor (HCBT) for the low-cost BiCMOS technology

A new Horizontal Current Bipolar Transistor (HCBT) is developed and integrated with a commercial 0.18 µm CMOS technology resulting in a very low-cost BiCMOS technology suitable for wireless applications. The number of fabrication steps is significantly reduced in comparison to conventional vertical-current bipolar transistors. The optimum HCBT performance can be achieved by 3 additional masks to CMOS process while an even simpler version with 2 additional masks is also demonstrated. The integration of HCBT with bulk CMOS is achieved by introducing innovative process steps such as protecting the active transistor region during polysilicon etching by low-resistance native oxide, placement of high-doped emitter and collector regions in oxide trenches etc. The compact HCBT structure has small junction capacitances and fT and fmax of 34 GHz and 45 GHz, respectively, with BVCEO=3.4 V.