SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

摘要

PURPOSE:To make it possible to arrange MOS transistors in the close proximity and to improve the integration density of a device by forming the base electrode of a bipolar transistor in the same step at either of the step for foming P-type or N-type polycrystalline silicon layer. CONSTITUTION:The following steps are provided: the step for forming the gate electrode of one MOS transistor Q1 with a P-type polycrystalline silicon layer 9; the step for covering the side surface of the P-type polycrystalline silicon layer 8 with an insulating film 12; and the step for forming the gate electrode of another MOS transistor Q2 with an N-type polycrystalline silicon layer 10. A base electrode B of a bipolar transistor is formed in the same step as the step for forming either of the P-type polycrystalline silicon layer 9 or the N-type polycrystalline silicon layer. Thus, the high integration density of the device can be achieved without increasing the manufacturing steps.