PROGRESS TOWARDS COPPER CMP IN A CARBON DIOXIDE MATRIX

摘要

Water-based chemical mechanical planarization (CMP) faces several technical challenges as the semiconductor industry implements porous low K interlayer dielectrics. For example, nanoporous materials can adsorb water, changing their performance characteristics. Additional environmental limitations exist with the vast amounts of ultrapure water necessary for the slurries and the large volume of toxic effluent produced. Thus, we are focused on developing a "dry" carbon dioxide (CO_2) based CMP process. The first step in developing this process requires an understanding of copper oxidation and dissolution in the non-polar CO_2 media. We have successfully oxidized and chelated copper metal in CO_2 using organic peroxides and a β-diketone chelating agents. Copper chelation kinetics have been monitored and characterized by infrared and UV-visible spectroscopies. Surface analyses have been accomplished by x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Finally, electrochemical measurements made in condensed CO_2 using both platinum and copper working electrodes were conducted.