Corrosion in Aluminum Chemical Mechanical Planarization for Sub-Quarter Micron Dynamic Random Access Memory Devices

Abstract

In the Al chemical mechanical planarization (CMP) process, which is aimed at the application of Al damascene to sub-quarter-micron dynamic random access memory (DRAM) interconnection, corrosion has been the main focus of investigation. The corrosion characteristics vary accordingly to the deposition conditions of the Al and metal structures. Galvanic corrosion seemed to be the major corrosive mechanism at the Al interface. The dependency of corrosion on pattern size was also examined. To prevent corrosion, hydrogen peroxide treatment of the Al surface and reduction of the contact with deionized water were both highly effective. The Al damascene process was applied with the corrosion reduction method to Al lines down to 0.24 µm width, resulting in an approximate 9% decrease in the sheet resistance.