Method of manufacturing semiconductor device

Claim 1

A method of manufacturing a bipolar transistor including at least a collector region of a first conductivity type on a semiconductor substrate, a base region of a second conductivity type formed in the collector region of the first conductivity type, and an insulating film having at least one opening in the base region, comprising the steps of: forming an insulating film on a base region to have an opening in a prospective base forming region of a semiconductor substrate; forming a polycrystalline semiconductor layer entirely doped with an impurity of the first conductivity type; selectively etching a prospective base electrode forming region and a prospective collector electrode forming region of said polycrystalline semiconductor layer; diffusing an impurity of the first conductivity type in a base region through said opening of said insulating film in said base region to form an emitter region of the first conductivity type; and selectively removing said insulating film using said polycrystalline semiconductor layer as a mask to form base and collector electrode contact holes; forming a conductive layer on an entire surface of a resultant structure; selectively etching said conductive layer and said polycrystalline semiconductor layer.

Claim 2

A method of manufacturing a bipolar transistor including at least a collector region of a first conductivity type on a semiconductor substrate, a base region of a second conductivity type formed in the collector region of the first conductivity type, and an insulating film having at least one opening in the base region, comprising the steps of: forming an insulating film on a base region to have an opening in a prospective base forming region of a semiconductor substrate; forming a polycrystalline semiconductor layer entirely doped with an impurity of the first conductivity type; selectively etching a prospective base electrode forming region and a prospective collector electrode forming region of said polycrystalline semiconductor layer; diffusing an impurity of the first conductivity type in a base region through said opening of said insulating film in said base region to form an emitter region of the first conductivity type; and selectively removing said insulating film using said polycrystalline semiconductor layer as a mask to form base and collector electrode contact holes; forming a conductive layer on an entire surface of a resultant structure; selectively etching said conductive layer and said polycrystalline semiconductor layer.