Microstructure Evolution and Resistivity of Cu(B) Alloy Films on Ti Underlayer at the Early Stage of Annealing at 500 ℃

Abstract

This study examined the time dependence of the microstructural evolution and resistivity of Cu(B) alloy thin films deposited on a Ti underlayer during rapid thermal annealing at 500°C. The growth of bimodal distributed grains began at approximately 20 s. The B that precipitated from the supersaturated solid solution dissolved and then out-diffused to the Ti underlayer. This led to a decrease in size (r) and volume fraction (f) of the B precipitates, which limited the growth of the small Cu grains (G a ) according to the Zener relationG a ∼rlf. The average size of the small grains and the volume fraction of B precipitates varied with time, according toG a ∼(time)0.67 and f∼(time)1.0, respectively. Therefore, the decrease in the size of B precipitates occurred according to the relation r∼(time)0.33, suggesting that the dissolution of B precipitates occurs through lattice diffusion. The resistivity ρ G varied with time according to ρ G ∼(time)0.65, in a similar manner to the time dependence of the Cu grain size, indicating that pinned grain growth is the main contributor to the resistivity of Cu(B) alloy films.