Method for producing semiconductor integrated circuit device

摘要

A method for producing a memory LSI having in its peripheral circuitry an MISFET of LDD structure and a vertical type bipolar transistor is disclosed. More particularly, an impurity for forming a low impurity concentration region of the said MISFET of LDD structure is introduced sideways of an emitter-base junction of the bipolar transistor. By the introduction of the said impurity, an effective impurity concentration near the base surface is reduced and the cut-off frequency of the bipolar transistor is improved.