Thermal Reactions of Cu/TiN/Ti/FSG and Cu/TiN/Ti/OSG Multilayers at Elevated Temperatures

Abstract

Thermal reactions of Cu/TiN/Ti/fluorinated silicate glass (FSG) and Cu/TiN/Ti/organosilicate glass systems (OSG), after annealing in vacuum at 400-900°C, have been investigated by using sheet resistance measurement, scanning electron microscopy, glancing incident angle X-ray diffraction, and Auger electron spectroscopy. Sheet resistance values of both systems after annealing at 400-800°C are lower than that of the as-deposited samples. Nevertheless, after annealing at 900°C, the sheet resistances of both systems become more than twice the as-deposited values. The decreasing of sheet resistance values was due to the grain growth of copper films of both systems. X-ray diffraction revealed no newly formed phases after annealing. However, copperless patches are seen on the surface of both systems after annealing at 900°C. The patches are in irregular shape for the FSG sample but are circular for the OSG sample. In addition, penetration of Ti atoms across the copper film and out-diffusion of oxygen from FSG and OSG to the TiN/Ti barrier layer are observed for both Cu/TiN/Ti/FSG and Cu/TiN/Ti/OSG systems after annealing at 700-900°C. The accumulation of Ti on the Cu surface is more significant for the FSG than the OSG system. The interdiffusion and reaction characteristics of the two multilayer structures upon vacuum annealing are discussed. © 2002 The Electrochemical Society. All rights reserved.