Method of forming bipolar transistor having self-aligned emitter-base

Abstract

Selective and non-selective epitaxial growth is utilized to form a bipolar transistor having self-aligned emitter and base regions. A substrate of semiconductor material of a first conductivity type is provided and a first layer of semiconductor material of a second conductivity type is non-selectively epitaxially grown on the substrate. An insulating element is formed on a portion of the first layer of semiconductor material and a second layer of semiconductor material of the second conductivity type is selectively epitaxially grown on the first layer such that a portion of the second layer laterally overgrows onto an upper surface of the insulating element. The lateral overgrowth forms an aperture in the second layer to expose a region of the upper surface of insulating element. A layer of insulating material is formed on the second layer to isolate the second layer of semiconductor material from a subsequent deposition of conductive material. The portion of the insulating layer formed within the aperture narrows the aperture and the exposed region of the element. The exposed region of the element is removed to expose a portion of the first layer and an emitter region of the first conductivity type is formed in the first layer through the aperture.