Lithography process optimization for emitter window in sige-HBT device

摘要

Emitter window (EW) of SiGe-HBT is the region which connects the Base and Emitter and forms the EB junction. The size of EW determines the device operation current. Larger size provides larger current and even 0.02um of EW size shift will cause device characteristic drift. Thus the size and shape of EW are critical in process and EW is a great challenge for lithography to form an ideal small rectangle. Therefore special lithography process solutions are needed to ensure the fidelity of EW. In this paper, the minimum EW size requirement is 0.2 μm × 0.5μm and low cost KrF tool is used for the process. The reflectivity properties of SiGe, DARC, BARC and photoresist films impacts on lithography process are studied. The optical coefficient impacts to pattern resolution and production capability are investigated. An optimized OPC solution is also demonstrated. Finally, a high fidelity small size EW lithography solution is realized with features of low cost, high stability and easy manufacturing.