PREPARATION OF BIPOLAR ELEMENT USING POLYCRYSTALINE SILICON

PURPOSE: To provide a producing method for bipolar element, which prevents the damage of active area surface and the increase of emitter resistance and is suitable for multilayer wiring required for high speed and high integration. CONSTITUTION: An emitter silicon 9 is formed and next, a base polycrystal silicon 17 is formed. By removing the silicon 17 at a section on an emitter through a flattening process and a dry etching process utilizing an oxidized film and a double photoresist, the contact of metal 23 and silicon 9 is formed in an active area. Further, emitter width can be exactly formed in order to define the emitter polycrystal silicon through a photoetching method, bonding spikes to be generated at the time of direct ion implantation into the silicon can be decreased in order to form an active base based on deffusion caused by heat treatment with the ion implantation of boron into the silicon and on the final process stage, an extremely thin bond is formed by forming an emitter bond through a high-temperature quick heat treatment method with the ion implantation of arsenic into the silicon.