Method for fabricating bipolar transistor

The present invention relates to a method for fabricating a bipolar transistor, and more particularly relates to a method for fabricating a bipolar transistor in which epitaxial growth is not used. A method for fabricating a bipolar transistor includes: a first step of implanting, along the normal direction of the principle surface of a first-conductive-type semiconductor single crystalline substrates ions of a second-conductive-type first impurity into the semiconductor single crystalline substrate to form a second-conductive-type collector layer; a second step of implanting, along the direction tilted from the normal direction, ions of a second-conductive-type second impurity into the semiconductor single crystalline substrate at a higher injection energy than that in the ion implantation of the first step to form a buried collector layer in a lower portion of the collector layer; and a third step of forming each of a first-conductive-type base layer and a second-conductive-type emitter layer in a predetermined region of a surface portion of the collector layer.