TW252212B - Process of power bipolar transistor - Google Patents

Abstract

A process of power bipolar transistor, which is applicable to the first heavily doped semiconductor substrate as collector area of power bipolar transistor, includes: - forming the first doped layer, the first lightly doped layer, the second lightly doped layer, the second doped layer and mask layer in sequence; - forming opening on the destined position of mask layer; - with the mask layer as mask through the opening doping the first dopant into the second doped layer, and driving in to under the mask layer to form the first heavily doped area; - with the mask layer as mask through the opening forming trench, and the trench across the second doped layer to the second lightly doped layer; - doping the first dopant to the second doped layer in the trench and the second lightly doped layer to form the first doped area surrounding the trench and adjacent to the first heavily doped area; - forming conductive layer in the trench, and doping the first dopant to the conductive layer so as to through the conductive layer diffusing to the first heavily doped area and the first doped area to form the first diffused area, and the dopant density of the first diffused area is greater than the first heavily doped area's in order to become the emitter area of power bipolar transistor.