Bipolar transistor integrated with metal gate CMOS devices

A semiconductor structure comprising:

• at least one metal-oxide-semiconductor (MOS) transistor located on a first portion of a semiconductor substrate, said at least one MOS transistor including a high dielectric constant (high-k) gate dielectric having a dielectric constant greater than 3.9;
• and
• a bipolar junction transistor (BJT) located on a second portion of said semiconductor substrate, said BJT including a collector located in said semiconductor substrate and laterally surrounded by at least one shallow trench isolation structure, an epitaxial base located on said collector, a first polycrystalline extrinsic base portion contacting an entirety of sidewalls of said epitaxial base, a second polycrystalline extrinsic base portion contacting an entirety of outer sidewalls of said first polycrystalline extrinsic base portion, and an emitter contacting said epitaxial base and said first polycrystalline extrinsic base portion but not contacting said second polycrystalline extrinsic base portion.