BIPOLAR TRANSISTOR WITH RAISED EXTRINSIC BASE FABRICATED IN AN INTEGRATED BICMOS CIRCUIT

A PROCESS FOR FORMING A BIPOLAR TRANSISTOR WITH A RAISED EXTRINSIC BASE, AN EMITTER, AND A COLLECTOR INTEGRATER WITH A CMOS CIRCUIT WITH A GATE. AN INTERMEDIATE SEMICONDUCTOR STRUCTURE IS PROVIDED HAVING CMOS AND BIPOLAR AREAS. AN INTRINSIC BASE LAYER IS PROVIDED IN THE BIPOLAR AREA. A BASE OXIDE IS FORMED ACROSS, AND A SACRIFICIAL EMITTER STACK SILICON LAYER IS DEPOSITED ON, BOTH THE CMOS AND BIPOLAR AREAS. A PHOTORESISTIS APPLIED TO PROTECT THE BIPOLAR AREA AND THE STRUCTURE IS ETCHED TO REMOVE THE SACRIFICIAL LAYER FROM THE CMOS AREA ONLY SUCH THAT THE TOP SURFACE OF THE SACRIFICIAL LAYER ON THE BIPOLAR STOP LAYER IS DEPOSITED HAVING A SUBSTANTIALLY FLUSH WITH THE TOP SURFACE OF THE CMOS AREA. FINALLY, A POLISH STOP LAYER IS DEPOSITED HAVING A SUBSTANTIALLY FLAT TOP SURFACE ACROSS BOTHTHE CMOS AND BIPOLAR AREAS SUITABLE FOR SUBSEQUENT CHEMICAL-MECHANICAL POLISHING (CMP) TO FORM THE RAISED EXTRINSIC BASE.