Interdiffusions and Reactions in Cu/TiN/Ti/Thermal SiO2 and Cu/TiN/Ti/Hydrogen Silsesquioxane Multilayer Structures

Interdiffusion and thermal reactions in the Cu/TiN/Ti/thermal SiO2 and Cu/TiN/Ti/hydrogen silsesquioxane ~HSQ! multilayer structures on silicon wafers, as-deposited and after annealing in vacuum at 400-800°C, have been investigated by using sheet resistance measurement, scanning electron microscopy, glancing incident angle X-ray diffraction ~GIAXRD!, and Auger electron spectroscopy. The sheet resistance values of both systems decreased after annealing up to 600°C and began to increase after annealing at 700°C. The decrease in sheet resistance occurred in conjunction with grain growth of the copper films, while the increase of sheet resistance was related with oxygen incorporation into the TiN-Ti layers. After annealing at 800°C, the surfaces of both systems consisted of Cu-color area and gray dots. Microvoids were seen on the Cu-color areas of both systems. Both microvoids and gray dots existed in greater number and larger sizes for the HSQ sample, and GIAXRD revealed the existence of Cu3Si phase in the 800°C annealed HSQ sample. The interdiffusion and reaction characteristics of the two multilayer structures upon vacuum annealing are discussed.