PURPOSE: To simplify the processes for fabrication of the transistors provided with graft bases by forming the bases and the graft bases at a time by one time ion implantation.
CONSTITUTION: An Si nitride film 6 is selectively etched to form an oxide film 7. An oxide film 11 is formed and grooves 12 for isolating elements and grooves 13 for isolating collector contacts are formed. P type impurity such as boron is ion-implanted over the whole substrate to form P+ type channel stoppers at the bottom of the grooves 12 and to form P+ type graft base 15 and P type base 16 are formed in the active region at a time by the help of a difference of the masking properties against the ion implantation of the oxide film 7 and the Si nitride film 6. Phosphorus is ion-implanted to form an N+ type collector lead-out region 20 and arsenic or the like is introduced into the part 64 to form an N+ type emitter 22.
KAWAJI MOTONORI
TAKAKURA TOSHIHIKO
OKADA DAISUKE
