A method for manufacturing a semiconductor structure comprising complementary bipolar transistors, wherein for manufacture of a PNP-type structure, an emitter layer having a surface oxide layer is present on top of an NPN-type structure, the emitter layer comprising lateral and vertical surfaces, and wherein for removal of the oxide layer, an ion etching step is applied, wherein for the on etching step a plasma for providing ions is generated in a vacuum chamber by RF coupling and the generated ions are accelerated by an acceleration voltage between the plasma and a wafer comprising the semiconductor structure, and wherein the plasma generation and the ion acceleration are controlled independently from each other.