Planarization of copper layer for damascene interconnection by electrochemical polishing in alkali-based solution

In our present study, we have developed an advanced CMP process using electrochemical system, which is called the electrochemical polishing (ECP) process. The conventional CMP process uses various slurries, abrasives, and polishing pads. Recently, however, several difficulties and limitations have been reported in this CMP process. To overcome these technical issues, electrochemical polishing which removes copper atoms by electrochemical etching is proposed as a candidate for replacement of CMP process. In our experiment, we have investigated the electrochemical polishing of copper in alkali-based solution. The electrochemical polishing depends strongly on the composition of alkali-based solutions, and the profile of current density on copper film. From our preliminary experimental results, we concluded that ECP process should be applicable to the future device manufacturing technologies in microelectronics fabrication.