Bipolar transistor having a self-aligned base electrode and method for manufacturing the same

Claim 1

A bipolar transistor, comprising: a conductive semiconductor substrate having first and second pillars formed in first and second trenches each having a predetermined depth for defining an activated region and a collector region; a conductive impurities diffusing layer formed in the semiconductor substrate at a lower portion of the first and second trenches and at an isolation wall between the first and second trenches; a conductive base layer formed from the first pillar; a self-aligned base contact electrode insulated from the conductive impurities diffusing layer, connected to the conductive base layer through a base connecting portion and formed within the first trench wherein the connecting base portion is formed between the self-aligned based contact electrode and the conductive base layer is positioned at a sidewall of the first pillar, and is positioned to contact only a part of a sidewall of the self-aligned base contact electrode within the first trench; a conductive emitter layer formed on the base layer; and a collector contact electrode having a conductive type the same as the conductive impurities diffusing layer and formed by the second pillar of the second trench.