Studies On 20GHz SiGe HBT Device And Process

As wireless and communication markets grow, SiGe BiCMOS technology draws much attention among industries, with SiGe Hetero-junction Bipolar Transistor(HBT) being integrated with CMOS technology. It boasts high speed, high drive and low noise from SiGe HBT and features low power, high integration of CMOS. SiGe HBT technology is a key for SiGe BiCMOS process to realize high performance RF and Analog device. SiGe HBT brings strained SiGe material into bases realizing “band-gap engineering” which has been a challenge for conventional Silicon Bipolar transistor. It achieves high gain, low noise and high speed at same voltage, which makes it a perfect transistor. The paper presents SiGe HBT devices and a 0.35μm SiGe BiCMOS process which realizes both high voltage SiGe HBT and high speed one. Tape-outs for both are realized featuring current gain β of 180, Breakdown voltage BVCEO more than 6.5V, frequency fT of 25 GH.SiGe HBT devices are analyzed including base, emitter, collector etc. Based on CSEC 6 inch fab, 0.35μm SiGe BiCMOS process and device solution are determined to realize high speed SiGe HBT and high voltage one.0.35μm SiGe BiCMOS process is designed based on device structure, simulated by Silvaco TCAD in ways that determine process parameters and optimize device parameters. The simulation says the high voltage SiGe HBT has breakdown voltage BVCEO of 5V and frequency fT of 35 GHz and the high speed one gains breakdown voltage BVCEO of 2.5V and frequency fT of 70 GHz. RPCVD process helps grow SiGe hetero-junction solving problems arising from patterned substrate epitaxial surface, loading effects and taking challenges from fabrication control of epitaxial surface, defection, implantation, profiling and thickness. As a result, a qualified SiGe hetero-junction is achieved without strain relaxation.The processes of SiGe growth, Trench, base, emitter and ILD are successfully handled along the progress of taping-out. High voltage SiGe HBT and high speed one are realized with high voltage SiGe HBT featuring breakdown voltage more than 6.5V and characteristic frequency of 25 GHz, which meets the expectation of the program.