Tillverkningsmetod, varaktor samt integrerad krets

摘要

A method in the fabrication of an integrated bipolar circuit for forming a p/n-junction varactor is disclosed. The method featuring the steps of providing a p-doped substrate ( 10; 10, 41 ); forming a buried n⁺-doped region ( 31 ) in the substrate; forming in the substrate an n-doped region ( 41 ) above the buried n⁺-doped region ( 31 ); forming field isolation ( 81 ) around the n-doped region ( 41 ); multiple ion implanting the n-doped region ( 41 ); forming a p⁺-doped region ( 151 ) on the n-doped region ( 41 ); forming an n⁺-doped contact region to the buried n⁺-doped region ( 31 ), the contact region being separated from the n-doped region ( 41 ); and heat treating the hereby obtained structure to set the doping profiles of the doped regions. The multiple ion implantation of the n-doped region ( 41 ); the formation of the p⁺-doped region ( 151 ); and the heat treatment are performed to obtain a hyper-abrupt p⁺/n-junction within the n-doped region ( 41 ).