Semiconductor device

A semiconductor device comprising:

• a semiconductor substrate;
• a plurality of bipolar transistors provided on said semiconductor substrate, each of said plurality of bipolar transistors comprising:
• a collector region of a first conductivity type formed on said semiconductor substrate;
• a base region of a second conductivity type which is opposite said first conductivity type formed on said collector region, said base region including an intrinsic base region and an extrinsic base region surrounding said intrinsic base region;
• a field oxide layer formed on said semiconductor substrate and surrounding said base region;
• an emitter region of said first conductivity type formed on said intrinsic base region;
• a base polysilicon of said second conductivity type contacting said extrinsic base region and extending on said field oxide layer, an inner surface of said base polysilicon surrounding said intrinsic base region and defining a region where said intrinsic base region is formed;
• an emitter polysilicon of said first conductivity type contacting said emitter region and extending on said base polysilicon, said emitter polysilicon and said base polysilicon being electrically isolated from each other by a side wall spacer formed on said inner side surface of said base polysilicon;
• and
• a first insulating film formed on said base polysilicon, said side wall spacer defining a region where said emitter region is formed;
• a second insulating film provided over said bipolar transistors;
• and
• a first wiring layer provided on said second insulating film, said first wiring layer being electrically connected to said bipolar transistors via a plurality of connection holes formed in said second insulating film, said first wiring layer including a first tungsten film and a second tungsten film formed over said first tungsten film, said first tungsten film contacting said second insulating film at said connection holes;
• a third insulating film formed over said first wiring layer;
• and
• a second wiring layer formed on said third insulating film, said second wiring layer including an aluminum film and electrically connected to said first wiring layer via a connection hole formed in said third insulating film.