Semiconductor device including bipolar transistor having shallowed base

Claim 1

A semiconductor device comprising: a semiconductor body of a first conductivity type having a bipolar transistor forming region and an insulated-gate FET forming region; a first semiconductor region of a second conductivity type provided in a portion of said insulated-gate FET forming region; a second semiconductor region of the second conductivity type provided in said bipolar transistor forming region, said second semiconductor region functioning as a first electrode layer of a bipolar transistor; a first insulated-gate FET of the second conductivity type provided in another portion of said insulated-gate FET forming region; a second insulated-gate FET of the first conductivity type provided in said first semiconductor region; an impurity shielding layer means having a property of hardly permitting passage of impurities of the first conductivity type and respectively provided over said first and second insulated-gate FETs; an impurity source film means provided on at least said second semiconductor region and said impurity shielding layer means, having an insulating property and containing impurities of the first conductivity type; a third semiconductor region of the second conductivity type provided in said second semiconductor region being in contact with said impurity source film means, said third semiconductor region containing the same impurity as the impurity of the second conductivity type contained in said impurity source film means, and functioning as a base of said bipolar transistor; and a fourth semiconductor region of the first conductivity type provided in said third semiconductor region and functioning as a second electrode layer of said bipolar transistor; wherein said impurity shielding layer means is a laminated film formed of a first insulating film provided on said the main surface of said semiconductor body and a second insulating film provided on said first insulating film.