A bipolar transistor is produced by processes employed in the manufacture of CMOS nonvolatile memory devices, and is part of an integrated circuit. The integrated circuit includes a semiconductor substrate having a first type of conductivity, a PMOS transistor formed in said substrate, an NMOS transistor formed in said substrate, and the bipolar transistor. The bipolar transistor includes: a buried semiconductor layer having a second type of conductivity placed at a prescribed depth from the surface of said bipolar transistor, an isolation semiconductor region having the second type of conductivity, in direct contact with said buried semiconductor layer, and suitable for delimiting a portion of said substrate, forming a base region; an emitter region formed within said base region having the second type of conductivity, a base contact region of said transistor formed within said base region having the first type of conductivity, a collector contact region formed within said isolation semiconductor region having the second type of conductivity, wherein said base region has a doping concentration between 1016 and 1017 atoms/cm3.