Effects of post-annealing by the rapid thermal process on the characteristics of MOCVD-Cu/TiN/Si structures

Effects of rapid thermal annealing on the characteristics of Cu films deposited from the (hfac)Cu(VTMS) precursor and on the barrier properties of TiN layers were studied. By the post-annealing, the electrical characteristics of Cu/TiN and the microstructures of Cu films were significantly changed. The properties of Cu films were more sensitive to the annealing temperature than the annealing time. Sheet resistances were decreased in 400-450 degrees C ranges, and abrupt increases were observed above 750 degrees C. It was also found that the copper films showed pronounced grain growth with the (Ill)preferred orientation. The grain growth and condensation of copper were observed below 500 degrees C without formation of the CuO and Cu2O phase resulting in surface degradation. Above 500 degrees C, the oxide compound of copper was partially formed on the surface and the inter-reaction on the Cu-TiN interface was started. The inter-reaction of Cu-Ti and Cu-Si interface vigorously occurred and the surface roughness was continuously deteriorated above 650 degrees C. It revealed that the optimum annealing conditions for MOCVD-Cu/PVD-TiN structures to enhance the electrical characteristics without degradation of TiN barriers were in the range of 400 degrees C.