Multiple transistor integrated circuit with thick copper interconnect

Abstract

An interconnection structure and method for a multiple transistor integrated circuit power device is disclosed. A power integrated circuit is formed of a plurality of source and drain diffusion regions to be coupled together to form the source and drain of multiple LDMOS transistors. Each diffusion region has a first metal layer stripe formed over it and in electrical contact with it. A second metal layer conductor is formed over a plurality of the first metal layer stripes, and selectively contacts the first metal layer stripes to form source and drain busses. Polysilicon gate busses are provided as well. A thick third metal layer is then formed over each second metal layer bus, either physically contacting it or selectively electrically contacting it. The thick third level metal is fabricated of a highly conductive material, such as copper. The resulting on resistance for the transistors on the integrated circuit is substantially reduced by the use of the thick third metal layer. Current debiasing and electromigration problems of the prior art are reduced or eliminated. A seven transistor integrated circuit formed from power transistors and incorporating the invention is described. Other devices, systems and methods are also disclosed.