The present invention provides a semiconductor device having a bipolar transistor
constructed so as to allow the adjustment of the base input signal voltage that
switches on a transistor in which a diffusion region of a different conductivity
type from that of the base region is formed at the contact of the base electrode,
and to allow the base current to be controlled when a digital transistor is produced.
A base electrode connection region 24 of an n+-type is provided
to a p-type base region 12, and a zener voltage control diffusion region
25 of a p+-type is provided around the periphery of the base
electrode connection region 24 so as to form a pn junction and undergo zener
breakdown at the desired voltage. A resistor 26 composed of polysilicon
is connected to the base electrode connection region 24 via a metal electrode
16a. As a result, this semiconductor device has a bipolar transistor
in which a zener diode ZD and the resistor 26 are serially built into the base.
