Selective Epitaxy Base Transistor (SEBT)

The first bipolar transistor using selective epitaxy for base formation in a double-poly self-aligned structure is presented. The intrinsic base was formed by a selective-epitaxial deposition in place of ion implantation. Such epitaxial base processes are capable of achieving a narrow intrinsic base width and a high Gummel number which will lower the pinched intrinsic base sheet resistance Rbi and base-emitter diffusion capacitance C^ compared to advanced ion-implanted processes. A selective epitaxial base can be simply introduced in advanced double-poly self-aligned processes compared to a nonselective epitaxial layer.